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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-1078; Project Identifier AD-2020-00716-A;
Amendment 39-22324; AD 2023-02-17]
RIN 2120-AA64
Airworthiness Directives; Textron Aviation Inc. (Type Certificate
Previously Held by Cessna Aircraft Company) Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD)
for all
Textron Aviation Inc. (type certificate previously held by Cessna
Aircraft Company) (Textron) Model 210N, 210R, P210N, P210R, T210N,
T210R, 177, 177A, 177B, 177RG, and F177RG airplanes. This AD was
prompted by the in-flight break-up of a Model T210M airplane in
Australia, due to fatigue cracking that initiated at a corrosion pit,
and subsequent corrosion reports on other Model 210- and 177-series
airplanes. This AD requires visual and eddy current inspections of the
carry-thru spar lower cap for corrosion, cracking, and damage;
corrective action if necessary; application of a protective coating and
corrosion inhibiting compound (CIC); and reporting the inspection
results to the FAA. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective March 20, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 20,
2023.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov by
searching for and locating Docket No. FAA-2020-1078; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this final rule, any
comments received, and other information. The address for Docket
Operations is U.S. Department of Transportation, Docket Operations, M-
30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue
SE, Washington, DC 20590.
For service information identified in this final rule,
contact Textron Aviation Inc., One Cessna Boulevard, Wichita, KS 67215;
phone: (316) 517-6061; email: structures@txtav.com; website:
support.cessna.com.
You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 901 Locust,
Kansas City, MO 64106. For information on the availability of this
material at the FAA, call (817) 222-5110. It is also available at
regulations.gov by searching for and locating Docket No. FAA-2020-1078.
FOR FURTHER INFORMATION CONTACT: Bobbie Kroetch, Aviation Safety
Engineer, Wichita ACO Branch, FAA, 1801 Airport Road, Wichita, KS
67209; phone: (316) 946-4155; email: bobbie.kroetch@faa.gov or
Wichita-COS@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all Textron Model 210N,
210R, P210N, P210R, T210N, T210R, 177, 177A, 177B, 177RG, and F177RG
airplanes. The NPRM published in the Federal Register on May 11, 2021
(86 FR 25812).
The NPRM was prompted by a report that, on May 26, 2019, a Textron
Model T210M airplane experienced an in-flight breakup while performing
low-altitude aerial survey operations in Australia. The carry-thru spar
failed and resulted in wing separation and loss of control of the
airplane. A visual examination of the fracture surface identified
fatigue cracking that initiated at a corrosion pit. The FAA issued an
airworthiness concern sheet (ACS) on June 27, 2019, advising owners and
operators of the accident and requesting relevant information about the
fleet.
Following the ACS, the FAA received reports of widespread and
severe corrosion of the carry-thru spar. Earlier Model 210G, T210G,
210H, T210H, 210J, T210J, 210K, T210K, 210L, T210L, 210M, and T210M
airplanes experienced the most widespread and severe corrosion, and the
FAA issued AD 2020-03-16, Amendment 39-21029 (85 FR 10043, February 21,
2020) (AD 2020-03-16) as an immediately adopted rule (Final Rule;
Request for Comments) to address the unsafe condition on those
airplanes.
The FAA also received reports of corrosion on later Model 210N,
P210N, T210N, 210R, P210R, and T210R airplanes and Model 177-series
airplanes. On Model 210N, P210N, T210N, 210R, P210R, and T210R
airplanes, the upper surface of the carry-thru spar is covered by
fuselage skin and is not exposed to the environment. This removes the
leak paths at the skin splices common to the earlier Model 210-series
airplanes and reduces the potential for moisture intrusion.
Additionally, the later Model 210-series airplanes were manufactured
with zinc chromate primer applied to all carry-thru spars. However, the
later Model 210-series airplanes were also delivered with foam
installed along the carry-thru spar lower cap. The foam traps moisture
against the lower surface of the carry-thru spar cap, which can aid in
the development of corrosion.
The Model 177-series airplanes share a similar carry-thru spar
design with the earlier Model 210-series airplanes: The upper surface
of the carry-thru spars are exposed, and the carry-thru spars might not
have been delivered with zinc chromate primer applied. Although Model
177-series airplanes were not delivered with foam padding installed on
the lower surface of the carry-thru spar, corrosion has been reported
on the carry-thru spar lower cap for these airplanes. Corrosion of the
carry-thru spar lower cap can lead to fatigue cracking or reduced
structural strength of the carry-thru spar, which, if not addressed,
could result in wing separation and loss of control of the airplane.
In the NPRM, the FAA proposed to require visual and eddy current
inspections of the carry-thru spar lower cap for corrosion, cracking,
and damage; corrective action if necessary; application of a protective
coating and CIC; and reporting the inspection results to the FAA. The
FAA is issuing this AD to address the unsafe condition on these
products.
Discussion of Final Airworthiness Directive
Comments
The FAA received comments from 124 commenters. The majority of
comments were from individuals. Organizations submitting comments
included the Aircraft Owners and Pilots Association (AOPA), Aviation
Plus LLC, Cardinal Flyers Online, and Textron. In addition, the FAA has
included
in the docket a discussion with the European Union Aviation Safety
Agency that clarifies the proposed NPRM. The following summarizes the
comments received on the NPRM and provides the FAA's responses.
A. Requests To Withdraw the NPRM
Comment summary: AOPA and numerous individual commenters requested
that the NPRM be withdrawn.
1. There Is No Unsafe Condition: Crash Was Maintenance/Operation Issue
Seven commenters stated that the NPRM was unnecessary because they
diligently inspect their airplanes and have not detected any problems
during their inspections. Three commenters explained that this crash
was due to a maintenance issue. One commenter questioned how the
accident airplane was maintained. Another commenter stated that an AD
is not necessary because the Model T210M spar fracture was due to heavy
use and lack of maintenance and that a service bulletin would be
sufficient. Several individual commenters discussed how the accident
airplane was operated, stating improper operation and operation outside
the standard limit of the airframe caused the accident.
Two commenters stated that there does not appear to be evidence
that a problem exists. One commenter stated that voluntary visual
inspections of the fleet have not exposed a widespread issue and noted
that all airplane structures are exposed to the same aging issues of
corrosion and fatigue and that the NPRM singles out Model 210- and 177-
series airplanes.
FAA response: The FAA disagrees with the commenters' requests to
withdraw the NPRM. Based on available data, including the corrosion and
damage reports received, the FAA disagrees that an unsafe condition
does not exist. While the in-flight break-up of a Model T210M airplane
in Australia was the catalyst for this AD, the FAA determined that
Model 210- and 177-series airplanes share a common single-load path
design constructed from the same material. Also, the FAA issued an ACS,
dated June 27, 2019, advising owners and operators of the accident and
requesting relevant information about the fleet. The reports gathered
in response to this ACS, combined with inspection reports received in
response to AD 2020-03-16, issued to address widespread and severe
corrosion of the carry-thru spars on Model 210G, T210G, 210H, T210H,
210J, T210J, 210K, T210K, 210L, T210L, 210M, and T210M airplanes,
revealed that carry-thru spars for Model 210- and 177-series airplanes
are subject to corrosion. Corrosion can initiate cracking, resulting in
a carry-thru spar being unable to carry the required load.
Australian Transport Safety Bureau (ATSB) Report AO-2019-026, In-
flight break-up involving Cessna T210M, VH-SUX, dated May 26, 2019
(ATSB AO-2019-026) does state, in part, that ``The cyclic loads induced
by the low-level survey flight profile were significantly greater than
those associated with the higher-level flight profile originally
intended for the aircraft type. This probably increased the risk of
fatigue-related structural failure.'' However, ATSB AO-2019-026 does
not list inadequate operator maintenance or identify improper operation
as contributing factors to the accident.
The FAA acknowledges that the carry-thru spar on individual
airplanes might not have findings of corrosion or damage. However, as
of January 13, 2023, the FAA has received 226 inspection reports from
operators of Model 210N, 210R, P210N, P210R, T210N, and T210R airplanes
that include 21 reports of corrosion and damage, with two carry-thru
spars removed from service. The FAA has also received 211 inspection
reports from operators of Textron Model 177-series airplanes that
include 120 reports of corrosion and at least 14 spars removed from
service due to corrosion or damage.
2. NPRM Was Overreaching
Three commenters stated that the NPRM was overreaching. One
commenter stated that the NPRM could be interpreted as punitive and
another commenter stated that it is overreaching because it cast a net
to include all Model 177-series airplanes and most Model 210-series
airplanes.
FAA response: The FAA disagrees with the commenters' requests to
withdraw the NPRM. Based on available data, including the corrosion and
damage reports received, the FAA disagrees that the NPRM was
overreaching by including all Model 210- and 177-series airplanes in
the applicability. The FAA agrees that other types and models of
airplanes have corrosion and fatigue issues, but this AD and its
compliance time are based on data for these model airplanes and the
nature of this unsafe condition. The applicability of this AD is all
Model 210- and 177-series airplanes with carry-thru spars manufactured
from 2014-T6 aluminum forging because this part is single-load path,
critical structure manufactured from a material susceptible to severe
corrosion.
3. NPRM Is Unnecessary: Use Existing Maintenance Directions, Service
Documents, or Issue a Special Airworthiness Information Bulletin (SAIB)
Six commenters requested the FAA withdraw the NPRM and allow
operators to rely upon the existing maintenance directions or service
documents. Another commenter stated that a Textron service letter
approach would be sufficient. One commenter stated that the service
information approach was the correct decision and that Textron should
provide data behind the request for the NPRM. The FAA infers that the
commenter is requesting that the NPRM be withdrawn in lieu of service
information. One commenter suggested that the FAA issue an SAIB instead
of an AD.
FAA Response: The FAA disagrees with the commenters' requests to
withdraw the NPRM. The procedures in Textron service letters are not
legally enforceable requirements. Similarly, the FAA could issue an
SAIB to draw attention to the inspections area, but an SAIB is
informational only. Thus, an AD is the only way the FAA can mandate the
procedures necessary to fix the unsafe condition.
Textron does not have the authority to determine if the FAA will or
will not issue an AD on a potential airworthiness issue. The FAA has
the regulatory authority to issue an AD and, in compliance with 14 CFR
39.5, issues an AD when it determines that an unsafe condition exists
that is likely to exist or develop in other products of the same type
design. For this AD, the FAA based its determination on data received
in response to the ACS dated June 27, 2019, inspection reports
completed on airplanes in the fleet, and data and analysis provided by
Textron and evaluated by the FAA.
Cessna previously identified the carry-thru spar as an area of
concern through the Continued Airworthiness Program (CAP) inspections,
introduced in 1992, as well as the later published supplemental
inspection documents (SIDs). Specifically, CAP Inspection Number 57-10-
08 for the Cessna 210 identifies inspections for the carry-thru spar
lower surface and additional inspection on the lower spar cap.
Subsequent inspections completed after the Model T210M accident in
Australia indicated that operators were not doing the voluntary
inspections specified in the SIDs.
B. Requests Regarding Data Justifying AD Action
Comment summary: Eleven commenters requested that the FAA provide
the data used to justify the NPRM. One commenter stated that pilots and
owners need access to the underlying data being used to make critical
decisions. Another commenter stated that neither the FAA nor Textron
presented any evidence of the corrosion issue existing in Model 210-
series airplanes that came from the factory with corrosion proofing
coating already applied, specifically the 1979 N-model and newer
airplanes, and suggested the FAA investigate the issue before taking
widespread steps to correct what may be a theoretical issue. An
additional commenter stated that no description is found specifying
what constitutes severe corrosion compared to non-severe corrosion and
requested to know how likely a carry-thru spar is to fail with
corrosion versus severe corrosion. Another commenter requested that the
FAA provide data to show there is a real threat to warrant immediate
intervention.
FAA response: The FAA agrees with the commenters' requests to
provide additional information regarding the data used to justify
issuing this AD. Prior to issuing AD 2020-03-16 and the NPRM for this
final rule, the FAA issued the ACS, dated June 27, 2019, advising
owners and operators of the accident involving the Model T210M airplane
in Australia and requesting relevant information about the fleet. The
FAA evaluated data obtained in response to the ACS and from inspection
reports completed in response to Textron Aviation Mandatory Single
Engine Service Letter, SEL-57-06, dated June 24, 2019 (Textron SEL-57-
06); Textron Aviation Single Engine Service Letter SEL-57-07, dated
June 24, 2019 (Textron SEL-57-07); and subsequent Textron service
letters that are identified in the Other Related Information paragraph.
The data demonstrated that the risk was higher in earlier Model 210
airplanes (Model 210G, T210G, 210H, T210H, 210J, T210J, 210K, T210K,
210L, T210L, 210M, and T210M airplanes), which supported issuing AD
2020-03-16 as an immediately adopted rule (Final Rule; Request for
Comments).
The data received for later Model 210- and 177-series airplanes
supported issuing the NPRM for this final rule. As of January 13, 2023,
the FAA has received inspections results for 226 Model 210N, 210R,
P210N, P210R, T210N, and T210R airplanes, including 21 reports of
corrosion and damage and 2 spars removed from service. None of these
later model airplanes reported cracking in the carry-thru spar. For
Model 177-series airplanes, the FAA has received inspections results
for 211 airplanes, including 120 reports of corrosion and at least 14
spars removed from service due to corrosion or damage. There have not
been any reports of cracking in the lower flange of the carry-thru
spars on Model 177-series airplanes.
Model 210- and 177-series airplanes share a similar carry-thru spar
design with similar geometry. The carry-thru spars are single-load
path, critical structure manufactured from 2014-T6 aluminum forging,
which is susceptible to intergranular corrosion. A description of
intergranular corrosion can be found in Chapter 2, Section 2.5.5, of
FAA Advisory Circular AC 43-4B, Corrosion Control for Aircraft, dated
September 11, 2018. Analysis completed by Textron demonstrated that the
carry-thru spars on Model 210- and 177-series airplanes experience
similar stress levels in operation. As of January 13, 2023, at least
six spars were reported to have suspected cracking associated with
corrosion in the lower flange of the carry-thru spar on early Model
210-series airplanes. For the carry-thru spar, severe corrosion is
demonstrated by blistering, scaling, flaking, or measuring in excess of
0.010-inch deep. Any corrosion that results in cracking also qualifies
as severe corrosion. Due to a large number of variables, the FAA cannot
predict how spars with varying degrees of theoretical corrosion could
fail in comparison to one another. However, the FAA's inability to
predict the precise moment of failure does not eliminate or invalidate
the unsafe condition.
The FAA determined that a longer compliance time than what is
required by AD 2020-03-16 was acceptable for addressing the identified
unsafe condition for later Model 210-series airplanes (Models 210N,
P210N, T210N, 210R, P210R, and T210R airplanes) and Model 177-series
airplanes, which is why those airplane models were not included in AD
2020-03-16 but are included in the applicability for this AD.
C. Requests Regarding Applicability
Numerous individual commenters requested changes to the
applicability of the proposed AD for a variety of reasons.
1. Accounting for Differences Between Model 210- and 177-Series
Airplanes
Comment summary: Thirteen commenters requested that the proposed AD
account for differences between Model 210- and 177-series airplanes,
including weight, operational usage, flight characteristics, wing
loading, and application of corrosion protection. Four commenters
stated that the FAA should account for the lack of interior foam
padding installed on the lower carry-thru spar cap lower surface on
Model 177-series airplanes as compared to Model 210-series airplanes.
Two commenters identified that Model 177-series airplanes lack an
interior bracket that is installed on Model 210-series airplanes, with
one commenter noting the straps are dissimilar metal. Another commenter
stated that corrosion on Model 177-series airplanes was found on the
spar web, lower cap to web radius, and upper surface of the lower cap,
as opposed to the Model 210-series airplanes where corrosion was found
on the lower surface of the lower cap.
FAA response: The FAA acknowledges that there are differences in
the carry-thru spars between Model 210- and 177-series airplanes. The
FAA agrees that any subsequent rulemaking for the carry-thru spars on
Model 210- and 177-series airplanes might not be the same. However,
this is an interim AD requiring a visual inspection, eddy current
inspection of the critical location, and corrosion treatment of the
spars, and the FAA has determined that this action is necessary to
address the unsafe condition for all affected airplanes.
Although the carry-thru spars for both Model 210- and 177-series
airplanes are constructed from the same 2014-T6 aluminum forgings, the
thicknesses of the caps are thinner on Model 177-series airplanes
compared to Model 210-series airplanes. While the carry-thru spars on
Model 177-series airplanes do not have interior foam adhered to the
lower carry-thru spar cap, the installation orientation of the carry-
thru spar in the airplane can result in moisture collecting on the
upper surface of the forward flange of the carry-thru spar lower cap,
and corrosion has been found on the tension-carrying lower cap. This AD
only requires inspecting the lower cap and not the upper cap, web, or
web to lower cap radius. Of the 120 reports of corrosion for Model 177-
series airplanes, 27 include findings of corrosion on the upper surface
of the lower carry-thru spar cap, an area included in the inspections
required by this AD. Many of the 120 reports included insufficient
information to identify the specific location of the corrosion.
Like the carry-thru spars on Model 210-series airplanes, some
carry-thru spars on Model 177-series airplanes
were treated with primer in the factory prior to delivery, though not
all spars were treated. This AD does account for the differences in
these carry-thru spars in the required corrosion protection
application. However, the existence of primer itself may not eliminate
the possibility that corrosion exists and the spars still must be
inspected. The FAA reviewed reports gathered in response to the ACS,
dated June 27, 2019, and in response to AD 2020-03-16, which
demonstrated that the carry-thru spars on both Model 210- and 177-
series airplanes are subject to corrosion. Corrosion can initiate a
crack, resulting in the carry-thru spar being unable to carry the
required load. Analysis demonstrates crack growth can happen on an
airplane under typical operation and in the original configuration. The
carry-thru spars installed on Model 210- and 177-series airplanes share
a similar single-load path design and geometry, are critical structure,
and are constructed of 2014-T6 aluminum forging, which is susceptible
to intergranular corrosion. Analysis completed by Textron demonstrated
that the carry-thru spars experience similar stress levels in typical
operation.
Although Model 177-series airplanes lack interior brackets that are
installed on Model 210-series airplanes, corrosion on Model 210-series
airplanes is not limited to the area surrounding the interior brackets
and has been reported in a variety of locations on the carry-thru spar
lower cap. The interior brackets installed on a limited number of Model
210-series airplanes are manufactured from 2024-T42 aluminum, which
would not cause dissimilar metal corrosion with the carry-thru spar
2014-T6 aluminum forging. Corrosion has also been reported on Model
210-series airplanes that do not have the interior brackets installed.
2. Removing Model 177-Series Airplanes
Comment summary: One commenter stated that Model 177-series
airplanes should not be included in the applicability of the proposed
AD because the Model T210M airplane involved in the Australia accident
was highly modified and flown in an aggressive manner that exceeded its
design parameters. Eight commenters stated that there is a lack of
service difficulty reports and failures associated with Model 177-
series airplanes to justify including them in the applicability of the
proposed AD. Three commenters stated that they did not find any issues
during their airplane inspections. One commenter requested that Model
F177RG airplanes be excluded from the applicability of the proposed AD
because they were delivered from the factory with an interior coating
of zinc chromate for corrosion protection.
Two commenters stated that the Cessna Model 177 community is
proactive regarding maintenance and has a strong type club. The FAA
infers that these commenters are requesting changes to the proposed AD
based on the proactive nature of the Cessna Model 177 community.
FAA response: The FAA does not agree with the commenters' requests
to remove Model 177-series airplanes from the applicability of this AD.
The justification for issuing this AD is not based solely on the
accident of the Model T210M airplane in Australia. Although that
accident was a catalyst, as mentioned previously, the carry-thru spars
on Model 210- and 177-series airplanes share a similar single-load path
design, are critical structure, and are constructed of 2014-T6 aluminum
forging, which is susceptible to intergranular corrosion. The FAA does
not dispute that carry-thru spars on individual airplanes may not be
affected by corrosion or damage; however, the reported inspection
results demonstrate that Model 177-series airplanes do have a high rate
of corrosion and damage.
The FAA agrees that the Cessna 177 community has a very strong type
club and many proactive owners and operators. However, the FAA
disagrees that Model 177-series airplanes should not be subject to the
actions defined in the proposed AD. Not all operators are proactive and
diligent in voluntarily inspecting for corrosion, so the inspections
must be mandated. Out of the 211 Model 177-series reports received by
the FAA as of January 13, 2023, 120 have reported corrosion. Of those,
at least 14 were removed from service due to corrosion or damage.
The FAA acknowledges that some Model 177-series carry-thru spars,
including those on Model F177RG airplanes, were treated with primer in
the factory prior to delivery. This AD does account for the differences
in these spars in the requirement to apply corrosion protection.
However, the FAA disagrees that airplanes delivered from the factory
with corrosion protection applied should be excluded from the AD, as
corrosion has been reported on airplanes with factory-applied corrosion
protection.
3. Removing Certain Model 210-Series Airplanes
Comment summary: Two commenters requested that later Model 210-
series airplanes (Models 210N, 210R, P210N, P210R, T210N, and T210R) be
removed from the applicability of the proposed AD because the cabin
roof skin is one piece and completely covers the carry-thru spars,
which prevents water entry. The commenters stated that these airplane
models were factory-primed prior to installation, which improves the
corrosion protection, and that none of the Model 210N and Model 210R
airplanes that they are responsible for have evidence of corrosion
related problems. One of the commenters stated that Model 210N
airplanes, especially Model P210N airplanes, should not be included in
the proposed AD because these airplanes have continuous fuselage skin
and have factory-applied zinc chromate coating and sealant applied on
the pressurized fuselage.
FAA response: The FAA acknowledges that later Model 210-series
airplanes, including Model 210N, 210R, P210N, P210R, T210N, and T210R
airplanes, are less susceptible to corrosion than the earlier Model
210-series airplanes. As of January 13, 2023, the FAA has received
inspection reports on 226 later Model 210-series airplanes, including
15 (7%) reporting corrosion. No later Model 210-series airplanes were
removed from service due to corrosion. Two carry-thru spars were
removed from service due to damage. This is compared to 47% of the
earlier Model 210-series airplanes reporting corrosion and 57% of the
Model 177-series airplane fleet reporting corrosion.
The combined features of factory primer, continuous skin, and
sealing, specifically associated with the pressurized airplanes, likely
contributed to the lower corrosion rate; however, carry-thru spars on
all Model 210-series airplanes have a similar carry-thru spar design
and the actions identified in this AD are appropriate for all Model
210-series airplanes. As previously discussed, the carry-thru spars
have a single-load path critical structure, and the spar is constructed
of 2014-T6 aluminum forging, which is susceptible to intergranular
corrosion. Additionally, analysis completed by Textron revealed that
later Model 210-series airplanes, due to their weight and
configuration, demonstrate higher stress levels in operation when
compared to earlier Model 210-series airplanes. Therefore, the critical
crack length--the length at which the crack reduces the capability of
the structure below that provided in the certification basis--is
smaller in the later Model 210-series airplanes. This AD is interim
action and the FAA will continue to evaluate the inspection reports
when determining final action for mitigating the identified unsafe
condition on Model 210-series airplanes.
4. Airplane Operation
Comment summary: Several commenters requested that the
applicability of the proposed AD take into account the type of airplane
operation. The commenters noted that the Model T210M airplane that
experienced the in-flight break-up was operated in a more severe manner
than the typical fleet. One commenter noted that Textron SEL-57-07
included similar visual and eddy current inspections as those in the
proposed AD but the effectivity was limited to airplanes flown with
severe usage, as defined by service and maintenance manual information.
Another commenter suggested that an evaluation be used similar to one
that was used for the Piper wing spar AD 2020-26-16, Amendment 39-21371
(86 FR 3769, January 15, 2021).
FAA response: The FAA reviewed inspection reports provided by
operators of the current fleet of Model 210- and 177-series airplanes,
which includes corrosion reports for airplanes operated in various
environments, ranging from mild to severe corrosion environments, and
under different types of operation. In addition, enforcement of an AD
based on airplane operation would be difficult because FAA regulations
do not require all operators to maintain records of operations based on
usage and many airplanes are utilized in different kinds of operations.
The FAA determined that an evaluation similar to the one used for
Piper wing spar AD 2020-26-16 is not appropriate for this AD. AD 2020-
26-16 requires calculating ``factored service hours'' for each main
wing spar to determine when an inspection is required. The application
of the ``factored service hours'' formula will identify when an
airplane meets the criteria for the eddy current inspection of the
lower main wing spar bolt holes and replacement of the wing spar on
affected Piper airplanes.
The unsafe condition on the Model 210-and 177-series airplanes
addressed by this AD involves both corrosion and cracking. The FAA
cannot use an evaluation similar to the one used for the Piper
airplanes to draw the same conclusions or correlations to the unsafe
condition addressed by this AD, as the unsafe condition associated with
AD 2020-26-16 is primarily associated with fatigue cracking concerns.
5. Primed and Unprimed Airplanes
Comment summary: One commenter requested that the FAA account for
the differences in primed and unprimed carry-thru spars on Model 177-
series airplanes in the proposed AD. The commenter explained that early
Model 177-series airplanes did not have protective coating (primer)
applied from the factory but mid and later year airplanes did.
FAA response: The FAA acknowledges that carry-thru spars on some
Model 177-series airplanes were treated with primer in the factory
prior to delivery and this AD does account for the differences between
primed and unprimed airplanes regarding the requirement to apply
corrosion protection. However, the FAA disagrees that airplanes
delivered with factory-applied corrosion protection should be excluded
from the applicability of this AD. Corrosion has been reported on
airplanes with factory-applied corrosion protection and the carry-thru
spars on those airplanes must be inspected.
D. Requests Regarding Special Flight Permits
Comment summary: AOPA, Cardinal Flyers Online, and several
individual commenters requested that the FAA allow special flight
permits. The commenters explained that not all owners and operators
have local repair and maintenance facilities and that many repair and
maintenance facilities cannot perform all of the actions necessary to
comply with the requirements specified in the proposed AD. The
commenters noted that paragraph (m) of the proposed AD prohibited
special flight permits, which would prohibit any flight to complete the
visual and eddy current inspections specified in the proposed AD;
therefore, all visual inspections and on-condition blending must either
be completed at a facility with eddy current capability or would
require an inspector with such capability to travel to the airplane.
The commenters stated that allowing special flight permits would allow
more facilities to complete individual portions of the inspection,
increasing capacity and alleviating backlog at aircraft maintenance
facilities. The commenters stated that allowing special flight permits
could increase repair quality, improve scheduling, reduce costs, and
encourage more owners to complete the inspections, increasing the
safety of the fleet. Prohibiting special flight permits, however, could
result in the inability to repair the affected airplanes. In addition,
four commenters stated that the lack of documented failures for the
Model 177 does not justify the prohibition of special flight permits.
FAA response: The FAA partially agrees with the commenters'
requests and revised paragraph (m) of this AD to allow special flight
permits in limited situations because it would grant owners and
operators more flexibility when complying with the required actions in
this AD and reduce the burden on inspection facilities and mechanics.
The FAA revised paragraph (g)(4) of this AD to allow airplanes
without detected corrosion, cracking, or other damage, or evidence of
previous corrosion removal to continue to operate and complete the eddy
current inspection required by paragraph (h) of this AD within 200
hours TIS after the effective date of the AD or within 12 months after
the effective date of this AD, whichever occurs first.
The FAA agrees with allowing an airplane with evidence of corrosion
to be relocated if the process for obtaining a special flight permit is
completed in accordance with FAA regulations, policy, and guidance.
Furthermore, the FAA agrees with allowing an airplane with damage other
than corrosion or evidence of previous blending to be relocated,
provided the Wichita ACO Branch is contacted and provides concurrence.
The FAA disagrees with granting special flight permits if either
the visual inspection or the eddy current inspection detects cracking
in the carry-thru spar lower cap.
E. Requests Regarding Compliance Time
1. Extend the Compliance Time for the Required Inspections
Comment summary: AOPA, Aviation Plus LLC, Cardinal Flyers Online,
and numerous individual commenters requested that the compliance time
be extended for the visual inspection specified in paragraph (g) of the
proposed AD (within 200 hours time-in-service (TIS) or within 12 months
after the effective date, whichever occurs first). Four commenters
suggested the compliance time be 200 hours TIS or within 12 months
after the effective date of the AD, whichever occurs later. Two
commenters suggested requiring the visual inspection within 12 months
after the effective date of the AD, but not requiring the eddy current
inspection required by paragraph (h) of the proposed AD within that
timeframe. Several commenters remarked that TIS is more critical than
calendar time and requested the FAA remove the 12 month time
requirement to complete the visual inspection. One commenter suggested
the compliance time be changed to 200 hours TIS or the next annual
inspection after the issuance of the AD, whichever occurs first. Two commenters
provided additional compliance times, ranging from 36 months or 500
hours TIS to 5 years and 200 hours TIS. Eleven commenters noted that
the 12-month calendar limit would make compliance difficult due to
limited availability of maintenance facilities and personnel,
potentially grounding airplanes. Several commenters raised concerns
that there are not enough qualified maintenance facilities to handle
the workload of the inspection within a 12-month period, especially
given the prohibition on special flight permits and the requirements of
an AD for the Piper wing spar.
One commenter mentioned that most Textron Model 177-series
airplanes are flown less than 200 hours per year and three commenters
identified that no carry-thru spars have failed on the Textron Model
177-series airplanes. The FAA infers that these commenters are thus
requesting an increase in the compliance time for the inspections
required by this AD.
FAA response: Based on the inspection reports received, the FAA
disagrees with extending the compliance times specified in paragraph
(g) of this AD. The compliance times specified in this AD correspond
with the compliance times published in Textron Aviation Mandatory
Single Engine Service Letter, SEL-57-08, Revision 2, dated August 3,
2020 (Textron SEL-57-08R2) and Textron Aviation Single Engine Service
Letter SEL-57-09R1, dated August 3, 2020 (Textron SEL-57-09R1). Textron
superseded Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-07, Revision 1, dated November 19, 2019 (Textron SEL-57-07R1),
with Textron SEL-57-09R1, which identifies a compliance time of 200
flight hours or the next annual inspection from date of receipt, of
that service letter, whichever occurs first.
The FAA does not agree with a compliance time based solely on usage
TIS or on calendar time, nor does the FAA agree that the compliance
time should be ``200 hours TIS or 12 months, whichever occurs later''
after the effective date of this AD. The carry-thru spar is a critical
single-load path structure, and if a crack initiates, there could be a
catastrophic failure. Corrosion is a function of calendar time and
crack growth is a function of hours TIS. The FAA has received reports
of severe corrosion on carry-thru spars with less than 4,000 hours TIS
and corrosion could initiate cracking in structure with low hours TIS.
The FAA does not agree with revising the compliance time to ``200
hours TIS or next annual inspection after the issuance of this AD,
whichever occurs first'' because if the next annual inspection is due
before 12 months after the effective date of this AD that would be more
restrictive than the language in the proposed AD, and could occur
almost immediately. Operators can always accomplish the actions
required by an AD prior to the compliance time specified in an AD.
The FAA has revised paragraph (g)(4) of this AD to allow airplanes
without detected corrosion, cracking, or other damage, or evidence of
previous corrosion removal to do the eddy current inspection required
by paragraph (h) of this AD within 200 hours TIS after the effective
date of this AD or within 12 calendar months after the effective date
of this AD, whichever occurs first.
The FAA acknowledges both the limitations on the availability of
maintenance facilities and personnel capable of completing the
inspections required in this AD and the difficulty in meeting the
compliance time in paragraph (g) of this AD without the ability to
relocate the airplane. The FAA would entertain alternative methods of
compliance (AMOCs) to extend the compliance time on a case-by-case
basis provided the work was scheduled. If scheduling an eddy current
inspection is difficult, an owner, operator, or any interested party
can apply for an AMOC using the procedures in paragraph (n) of this AD.
The AMOC request must include substantiating data showing that the
proposed AMOC provides an acceptable level of safety for a different
method or adjustment of the compliance time to address the unsafe
condition, other than the one specified in the AD. Also, the FAA has
revised paragraph (g)(4) in this AD to allow airplanes without detected
corrosion, cracking, or other damage, or evidence of previous corrosion
removal to complete the actions required by paragraph (h) of this AD
within 200 hours TIS after the effective date of this AD or within 12
months after the effective date of this AD, whichever occurs first. As
discussed above in section D., Requests Regarding Special Flight
Permits, the FAA has revised paragraph (m) of this AD to allow special
flight permits in limited situations.
2. Correspond Compliance Time for Eddy Current Inspection With Service
Letter
Comment summary: One commenter requested the FAA explain the
differences between the proposed AD requiring an eddy current
inspection within one year and the Textron service letter (Textron SEL-
57-07) that specified an eddy current inspection for most Model 177-
series airplanes at or after 15,000 hours TIS. The FAA infers that the
commenter is requesting the compliance time specified in the proposed
AD match what is in the Textron SEL-57-07.
FAA response: The FAA agrees that there are differences between the
compliance time in the proposed AD and Textron SEL-57-07. Textron
Aviation superseded Textron SEL-57-07 with Textron SEL-57-09R1, which
specifies a compliance time of 200 flight hours or the next annual
inspection from date of receipt, whichever occurs first. Textron SEL-
57-09R1 applies to all Model 177-series airplanes identified in this
service letter regardless of the total flight hours on the airframe.
The compliance time specified in this AD aligns with the compliance
time in Textron SEL-57-09R1 and there is no justification for aligning
the compliance time with what is specified in the superseded Textron
SEL-57-07.
3. Account for TIS
Comment summary: Nine commenters requested that the proposed AD
account for an airplane's TIS and one of those commenters noted that
the accident airplane had a high number of hours TIS. Three of those
commenters suggested a compliance time ranging from 2,500 hours TIS to
12,000 hours TIS. Several commenters cited high costs as justification
for only requiring airplanes with a high number of hours TIS to do the
actions specified in the proposed AD.
FAA response: The FAA disagrees with limiting the inspections
required by this AD to airplanes with a high number of hours TIS. This
AD is not based solely on the fatal 2019 accident in Australia
involving a Model T210M airplane. As of January 13, 2023, there have
been reports of corrosion on 120 Model 177-series airplanes, with at
least 14 spars removed from service due to corrosion and damage of the
lower cap, including a spar removed from service with less than 2,000
hours TIS. Additionally, 460 Model 210-series airplanes have reported
corrosion, with 64 spars removed from service due to corrosion and
damage, including five removed from service with less than 3,000 hours
TIS. Inspections based on TIS alone are not sufficient to identify and
address corrosion, as corrosion is a function of calendar time.
Corrosion can serve as a crack initiator, resulting in the spar being
unable to carry the required load. Analysis completed by Textron
demonstrates this crack growth can happen under typical operation.
4. Align Compliance Time With Maintenance Schedules
Comment summary: One commenter requested that the FAA allow the
inspections to be completed when the inspection area is exposed for
other maintenance. The FAA infers that the commenter is making this
request to reduce costs and airplane down time.
FAA response: The FAA acknowledges the commenter's request to limit
maintenance access to reduce the time and money spent to comply with
the requirements of this AD. However, the FAA considers this AD to be
interim action and is still evaluating what actions must be required
when issuing future rulemaking that will be considered final action to
address the identified unsafe condition. During this evaluation, the
FAA will consider if, for any future rulemaking, compliance times can
be developed that correspond with scheduled maintenance; however, for
this AD, the FAA does not agree with extending the compliance time for
the entire fleet. The compliance time of this AD is within 200 hours
TIS or 12 months after the effective date of this AD, whichever occurs
first. This compliance time may allow the actions to be accomplished at
the same time as regular maintenance, as the requirements of this AD
can always be completed early. An owner, operator, or any interested
party can apply for an AMOC to propose an adjustment of the compliance
time using the procedures in paragraph (n) of this AD. The AMOC request
must include substantiating data showing that the proposed AMOC
provides an acceptable level of safety for a different method or
adjustment of the compliance time to address the unsafe condition,
other than the one specified in the AD.
F. Requests Regarding Requiring Actions To Align With Service
Information
Comment summary: Sixteen commenters requested that the FAA only
require the actions specified in the Textron service information. One
commenter stated that general aviation is struggling, and due to costs
an AD should not require pilots to do any actions beyond those
specified in the Textron service information. Two additional commenters
mentioned the additional costs of repeating portions of the inspections
in areas that differed between the Textron service information and the
proposed AD. One commenter stated that the FAA should require the
airplane manufacturer to create service information that will preserve
the airworthiness of the carry-thru spar so compliance with the service
information will count if the service information is included in an AD.
Another commenter stated when the FAA overrides manufacturers' service
information with ADs airplane owners would become less willing to use
the information in future service bulletins because of concern that the
FAA would require duplication of the actions in the service bulletins
in an AD. One commenter stated that paragraph (g)(2) of the proposed AD
negates the directions in paragraph (B)(2) of Textron SEL-57-09R1
because the service letter states to ``Make sure to only remove the
minimum material necessary to blend the corroded surface with the
surrounding surface.''
FAA response: The FAA disagrees that this AD should only require
the actions specified in the Textron service information. After
reviewing the procedures specified in that service information, the FAA
determined that the unsafe condition could not be mitigated using only
those procedures. Prior to the publication of the NPRM, the FAA
received reports indicating that the visual inspection might not detect
corrosion similar to that observed on the accident airplane. The
fatigue crack on the accident airplane that caused the catastrophic
failure of the carry-thru spar initiated at a corrosion pit
approximately 0.011-inch deep. Cracking may be difficult to detect
through visual inspection alone since the lower spar cap is in
compression during the inspection. The eddy current inspection,
however, could detect cracking from undetected corrosion or damage.
The FAA disagrees that paragraph (g)(2) of this AD negates the
directions in step 6.B.(2) of the Accomplishment Instruction in Textron
SEL-57-09R1. Paragraph (g)(2) of this AD addresses removal or repair of
the carry-thru spar due to evidence of previous blending. The FAA
agrees with granting credit for blending previously completed using
Textron service letters and the FAA acknowledges that owners,
operators, and maintenance personnel could have proactively completed
the actions described in the Textron service letters. The FAA has
revised paragraph (l) of this AD to clarify credit for previous
blending completed using the procedures in older revisions of the
Textron service letters. Paragraph (f) of this AD already provides
credit for blending action completed prior to the effective date of
this AD using Textron SEL-57-08R2 or Textron SEL-57-09R1.
The FAA agrees that alignment of a manufacturer's service documents
and the requirements of an AD is ideal; however, the FAA cannot mandate
a company to issue specific service information. Per 14 CFR 39.27, if
an AD conflicts with the service document on which it is based, then
the operator must follow the requirements of the AD. Additionally, the
Textron service information clearly indicates that the compliance time
presented might not apply to modified airplanes, including
modifications that alter the airplane's design, gross weight, or
airplane performance, including, but not limited to, installation of
vortex generators, wing cuffs, short take-off and landing (STOL) kits,
wing tips, and add-on wing fuel tanks. The FAA is responsible for
considering the effects of these modifications on the airplanes
included in the applicability of this AD.
While the FAA cannot mandate that the service information be
revised, nor can the agency wait on such information to address the
unsafe condition, the FAA may allow an AMOC if the service information
is revised and the FAA finds it acceptable to address the unsafe
condition. If Textron revises its service information and the FAA
determines that the revisions mitigate the unsafe condition, an owner,
operator, or any interested party can apply for an AMOC using the
procedures in paragraph (n) of this AD. The AMOC request must include
substantiating data showing that the proposed AMOC provides an
acceptable level of safety for a different method to address the unsafe
condition, other than the one specified in the AD.
The FAA has not changed this AD in regard to this issue.
G. Requests Regarding Limiting the AD to the Lower Carry-Thru Spar Cap
Comment summary: Two individual commenters requested the
requirements of the proposed AD be limited to inspections on the lower
carry-thru spar cap. Another commenter supported the focus on the lower
spar flange but noted that, in the proposed AD, mechanics could miss
the statement that limits the scope of the inspection. One commenter
acknowledged that the NPRM specified a mechanic is not required to
inspect the lower cap to web radius, spar web, upper cap, or lugs, but
that nothing excludes a mechanic from taking a spar out of service if
any evidence of previous blending in those areas is found.
FAA response: The FAA agrees with the commenter's requests to limit
the requirements of this AD to inspections of the lower carry-thru spar
cap and finds that, as written, the requirements of this AD are limited
to inspections of the carry-thru spar lower cap including the lower
surface, upper surface, and
edge. As detailed in paragraph (g) of this AD, inspecting the lower cap
to web radius, spar web, upper cap, or lugs is not required. The
preamble of this AD mentions that actions related to the web, upper
caps, and lugs are not included as part of this AD. A mechanic may take
a spar out of service during any inspection or maintenance event if the
airplane is determined to not be airworthy to return to service.
The FAA has not changed this AD in regard to this issue.
H. Requests Regarding Eddy Current Inspection
1. On-Condition Eddy Current Inspection
Comment summary: Thirty-five commenters requested that the eddy
current inspection of the carry-thru spar specified in paragraph (h) of
the proposed AD only be required as an on-condition action when there
is visual evidence of corrosion or damage. Three commenters stated that
corrosion or cracking on the lower surface of the spar should be
readily observable through a detailed visual inspection. Three
commenters requested data justifying the eddy current inspection on
airplanes that did not exhibit corrosion pitting on the carry-thru
spar. One commenter asked why an airplane would need an eddy current
inspection if the spar was delivered with a factory-applied protective
coating, is clean and dry, and is not operated in an environment
subject to moisture or other corrosion causing elements. Another
commenter noted that over 300 visual inspections were completed on
Model 177-series airplanes since the FAA identified this as a potential
concern and none of the reports indicated that cracking was found. A
different commenter requested that the FAA explain why it proposed
expanding Textron's inspection requirements, which only specified eddy
current inspections of the carry-thru spars if there were visual signs
of corrosion, and asked if the FAA had significant evidence or
engineering information indicating there could be internal corrosion or
cracking even though it's not visible on the surface. One commenter
stated that interpretation of the eddy current inspection results can
be subjective. Two commenters requested requiring repetitive visual
inspections instead of the eddy current inspection.
FAA's response: The FAA disagrees with the commenters' requests to
make the eddy current inspection an on-condition action in this AD or
to only require repetitive visual inspections. Prior to the publication
of the NPRM, the FAA reviewed inspection reports and determined that
the visual inspection might not detect corrosion. On the Model T210M
airplane involved in the accident that prompted the NPRM, the fatigue
crack initiated at a corrosion pit approximately 0.011-inch deep.
Cracking could be difficult to detect by only a visual inspection since
the lower spar cap is in compression during that inspection, and the
eddy current inspection could detect cracking from undetected corrosion
or damage. The FAA acknowledges that it has not received any reports of
cracking in the carry-thru spar lower cap on Model 177-series
airplanes; however, out of the 211 inspection reports received by the
FAA as of January 13, 2023, there have been 120 reports of corrosion
and at least 14 carry-thru spars have been removed from service due to
corrosion or damage.
This AD requires that the technician completing the eddy current
inspection be appropriately qualified as detailed in Textron Aviation
Mandatory Service Letters SEL-57-08, Revision 2; and SEL-57-09,
Revision 1.
The FAA has not changed this AD in regard to this issue.
2. Limited Availability of Inspectors
Comment summary: Several individual commenters expressed concern
regarding the limited number of inspectors qualified and available of
performing the eddy current inspection specified in the proposed AD.
The commenters explained that it is difficult to locate qualified eddy
current inspectors and for many airplane owners the inspectors are not
local. One commenter requested that the FAA research how many
facilities are willing to do the actions specified in the proposed AD
and identify the lead time for scheduling the work.
FAA response: The FAA acknowledges that finding a person or
facility qualified to do an eddy current inspection could be difficult
in some geographic regions. While the FAA does not maintain a
comprehensive listing of all repair stations capable of completing the
specific eddy current inspections required by this AD, you may search
for a repair station by location and rating on the FAA website: av-info.faa.gov/repairstation.asp.
The FAA has no way to accurately
determine any specific facility's willingness and scheduling
availability to complete work at a given time.
As discussed above in section D., Requests Regarding Special Flight
Permits, the FAA revised paragraph (m) of this AD to allow special
flight permits with limitations. If scheduling an eddy current
inspection is difficult, an owner, operator, or any interested party
can apply for an AMOC using the procedures in paragraph (n) of this AD.
The AMOC request must include substantiating data showing that the
proposed AMOC provides an acceptable level of safety for a different
method or adjustment of the compliance time to address the unsafe
condition, other than the one specified in the AD. Also, the FAA has
revised paragraph (g)(4) in this AD to allow airplanes without detected
corrosion, cracking, or other damage, or evidence of previous corrosion
removal to complete the actions required by paragraph (h) of this AD
within 200 hours TIS after the effective date of this AD or within 12
months after the effective date of this AD, whichever occurs first.
I. Requests Regarding Including a New Repetitive Inspection Requirement
Comment summary: Three individual commenters requested that the
proposed AD include repetitive inspections. One of the commenters
requested requiring repetitive inspections instead of replacing carry-
thru spars that fail the inspection but do not have evidence of
cracking. One of the commenters agreed that spars with cracking should
be removed from service but a questionable spar with no cracking should
be repetitively inspected instead of removed.
FAA response: The FAA agrees that repetitive inspections might be
appropriate for future rulemaking. The FAA considers this AD to be
interim action and is still evaluating what actions must be required if
future rulemaking is issued that will be considered final action. If
the FAA determines that repetitive inspections are necessary, then they
could be included as a requirement. Adding new requirements to this AD
would require public comment before adopting a final rule, and would
require publishing a supplemental NPRM. Because of the identified
unsafe condition, the FAA does not agree to delay this AD.
The FAA does not have data to support allowing carry-thru spars
with excessive material removed to remain in service, even if they are
repetitively inspected; however, the FAA would consider permitting
individual carry-thru spars to remain in service and be repetitively
inspected if an owner, operator, or any interested party applies for an
AMOC using the procedures in paragraph (n) of this AD and includes
substantiating data showing that the proposed AMOC provides an
acceptable level of safety.
The FAA has not changed this AD in regard to this issue.
J. Requests Regarding Removing Certain Requirements
1. Corrective Action Requirements
Comment summary: Textron requested that paragraphs (h)(3) and (4)
of the proposed AD, which address corrective actions for spars with
damage or corrosion, be removed. Textron stated that these paragraphs
are redundant because the inspection and rework specified in paragraph
(g) of the proposed AD would have already addressed these actions.
FAA response: The FAA does not agree because paragraphs (h)(3) and
(4) of this AD provide directions for what to do if damage or corrosion
are detected during the eddy current inspection required by paragraph
(h) of this AD. Paragraph (g) of this AD requires a visual inspection
with a 10X magnification lens looking for corrosion, cracking, and
damage and provides directions for what to do if damage or corrosion
are found during the visual inspection.
The FAA has not changed this AD in regard to this issue.
2. Corrosion Protection Requirement
Comment summary: An individual commenter stated that applying
corrosion coating would be costly and disruptive for parts that do not
need corrosion prevention. The FAA infers that the commenter is
requesting that the requirement to apply corrosion coatings specified
in the proposed AD be removed.
FAA response: The FAA disagrees that the requirement in paragraph
(i) of this AD to apply primer and CIC should be removed. Applying
primer and CIC prevents corrosion and reduces the potential for crack
initiation from corrosion. The carry-thru spar is a critical single
load path structure with a demonstrated corrosion issue. Failure to
sufficiently protect the structure from repeated corrosion increases
the likelihood of additional cracking.
The FAA has not changed this AD in regard to this issue.
K. Requests Regarding Credit for Previous Actions
1. Credit for Previous Blending
Comment summary: AOPA, Cardinal Flyers Online, and several
individual commenters requested that the proposed AD be revised to
either give credit for previous blending done before the effective date
of the final rule or to clarify what previous blending is acceptable.
Three commenters requested that the proposed AD be revised to provide
credit for carry-thru spars that were blended using the procedures
specified in the Textron service letters instead of the requirement to
replace a carry-thru spar or repair it using an AMOC. Ten commenters
requested that the proposed AD be revised to allow previous blending of
a carry-thru spar that is within the limits specified in the Textron
service letters, even if the blending was not done using the procedures
in the service letters. One commenter stated that it is unreasonable to
require removal from service of a carry-thru spar with evidence of
factory cleanup. The FAA infers that this commenter is requesting that
carry-thru spars that have evidence of prior blending be permitted to
remain in service.
Three commenters stated that, in the proposed AD, the language was
unclear regarding corrosion removed prior to the effective date of the
AD using the procedures in the Textron service letters. Paragraph
(g)(2) of the proposed AD would require that carry-thru spars with
evidence of previous blending either be removed from service or
repaired using an AMOC. The commenters noted that paragraph (l) of the
proposed AD does grant credit for the visual inspection required by
paragraph (g) of the proposed AD, but does not clearly identify if
credit is allowed for any previous corrosion removal completed as a
result of the visual inspection required by paragraph (g) of the
proposed AD.
Multiple commenters requested that the FAA provide credit for
previous corrosion removal, even if logbook records are used.
Commenters also raised the concern that owners who have made an effort
to maintain a carry-thru spar in good condition would be penalized if
the final rule fails to give credit for previous blending accomplished
using the procedures in Textron SEL-57-08R2, or Textron SEL-57-09R1, as
specified in paragraph (g) of the proposed AD. Ten commenters stated
that previous blending should be covered by paragraph (g)(3) of the
proposed AD and that all previous corrosion removal that does not
exceed the blend limits specified in Textron SEL-57-08R2 and Textron
SEL-57-09R1 should be permitted. Several commenters stated that the
language in paragraph (l) of the proposed AD was as ambiguous and may
penalize those parties who took action prior to publication of the
final rule. Several commenters stated that most carry-thru spars were
blended to some extent at the factory and that other carry-thru spars
were blended using guidance from Textron.
To justify allowing the blended carry-thru spars to remain in
service, one commenter provided information from an industry forum and
from experience working with cast aluminum to support the view that
Cessna blended carry-thru spars prior to delivery. This same commenter
also cited concerns regarding the time needed to obtain an AMOC.
FAA response: The FAA partially agrees with the commenters'
requests. The FAA agrees with granting credit for the blending of
carry-thru spars completed prior to the effective date of this AD using
Textron SEL-57-08R2 and Textron SEL-57-09R1, and the FAA acknowledges
that some owners, operators, and maintenance personnel proactively
complied with the procedures in that service information; however,
compliance with previous actions is already addressed and no change is
needed to this AD because paragraph (f) of this AD states ``Comply with
this AD within the compliance times specified, unless already done.''
The FAA also agrees to revise paragraphs (l)(1) and (2) of this AD
to clarify that owners and operators may take credit for corrosion
removal (blending) completed before the effective date of this AD using
the procedures in Textron Aviation Mandatory Single Engine Service
Letter SEL-57-08, dated November 1, 2019 (Textron SEL-57-08); Textron
Aviation Mandatory Single Engine Service Letter SEL-57-08, Revision 1,
dated November 19, 2019 (Textron SEL-57-08R1); Textron Aviation
Mandatory Single Service Letter SEL-57-09, dated November 19, 2019
(Textron SEL-57-09); Textron SEL-57-06; Textron Aviation Mandatory
Single Engine Service Letter SEL-57-06, Revision 1, dated November 19,
2019 (Textron SEL-57-06R1); Textron SEL-57-07; or Textron SEL-57-07R1.
The FAA disagrees allowing credit for blending completed prior to
the release of Textron SEL-57-06 and Textron SEL-57-07 without an
evaluation and a repair approved as an AMOC. While the FAA does not
have data supporting that Cessna blended the forged carry-thru spars
prior to delivery, the FAA does recognize that some carry-thru spars
were blended prior to publication of the NPRM. Blend limits, blend
ratios, and surface finish must be addressed in the AMOC request.
Locations previously blended that are included in the AMOC request will
still be required to complete the eddy current inspection or provide
evidence of previous completion.
2. Clarifying Credit for Previous Actions
Comment summary: Ten individual commenters requested clarification
regarding credit for previous actions. Four commenters stated that
paragraph (l) in the proposed AD was unclear. Seven commenters
requested the FAA give credit for previous actions and not require that
the actions be duplicated. One commenter stated that the proposed AD
should provide full credit for any previous corrosion remediation
performed using accepted maintenance procedures, so owners who
previously addressed corrosion on their airplane are not punished.
FAA response: The FAA agrees that credit should be granted for work
previously accomplished using the procedures in the Textron service
letters and, as stated previously, the FAA has revised paragraph (l) of
this AD to clarify that owners and operators may take credit for
previously accomplished visual inspections and corrosion removal if
completed in accordance with Textron service letters. The FAA finds
that owners and operators are not being required to duplicate actions
because paragraph (f) of this AD states ``Comply with this AD within
the compliance times specified, unless already done;'' therefore,
compliance for previous actions is granted to those who completed the
required actions prior to the effective date of this AD in accordance
with the applicable steps of the Accomplishment Instructions in Textron
SEL-57-08R2 and Textron SEL-57-09R1.
Operators that performed repairs using accepted maintenance
practices other than the Textron service letters must apply for an
AMOC.
L. Requests Regarding AMOCs
1. Repair
Comment summary: One commenter requested clarification regarding
what kinds of carry-thru spar repairs the FAA would approve through the
AMOC process. The commenter stated that paragraph (o) of the proposed
AD did not identify what kind of repairs might be acceptable and that
the proposed AD left the decision for acceptable AMOCs to Textron, even
though the FAA says Textron's corrective action identified in Textron
SEL-57-09R1 is not adequate. The commenter explained that the lack of
definition in paragraph (o) of the proposed AD regarding acceptable
repairs makes it difficult for owners to estimate the condition of
their carry-thru spars.
FAA response: The FAA disagrees that paragraph (n) of this AD
(paragraph (o) in the proposed AD), requires clarification. The FAA has
defined an acceptable repair based on available data. If the FAA knew
of additional standard repairs, then those repairs would have been
reviewed and, if found acceptable, included in this AD.
This AD specifies the same material removal limits as those
identified in Textron SEL-57-09R1. It is possible that spars with
damage that cannot be removed within the limits identified in Table 1
of Textron SEL-57-09R1 could still be found acceptable based on further
evaluation. A repair on a carry-thru spar for which the material
removed exceeds that identified in Table 1 of Textron SEL-57-09 would
require an AMOC. Generally, the FAA, not Textron, must approve AMOCs;
however, in this AD the FAA has delegated to Textron's Organization
Designation Authorization the authority to evaluate carry-thru spars
with material removal beyond that identified in Textron SEL-57-09R1 to
salvage as many spars as possible. Textron might choose not to evaluate
modified airplanes, as detailed in Textron SEL-57-09R1 and Textron SEL-
57-08R2. Additionally, there is no requirement for an operator to have
its spar evaluated by Textron. The owner or operator may develop its
own AMOC request to present to the FAA for evaluation of any repair for
which there is substantiating data.
The FAA would not limit AMOC options by defining those that are
acceptable, as it is unrealistic for the FAA to preemptively identify
and evaluate any potential AMOC option that may or may not be
applicable to an airplane.
The FAA has not changed this AD in regard to this issue.
2. Alternative Inspection Method
Comment summary: Cardinal Flyers Online and four individual
commenters requested that instead of the eddy current inspection a
visual inspection be allowed with the airplane on jacks. The commenters
explained that putting the wings on jacks would place the lower spar
cap in tension, allowing cracking to be seen more readily during the
visual inspection. One commenter proposed using a dye penetrant
inspection in addition to supporting the wings with jacks.
FAA response: The FAA acknowledges that other inspection methods
could be used for the carry-thru spar inspection; however, the FAA does
not have data to support including these alternative inspection methods
in this AD. An owner, operator, or any interested party may develop
inspection procedures and submit an AMOC request to the FAA along with
substantiating data showing that the proposed AMOC addresses the unsafe
condition with an acceptable level of safety.
The FAA has not changed this AD in regard to this issue.
3. Alternative Corrosion Protection Options
Comment summary: Three commenters requested that the proposed AD
allow for alternative corrosion protection options in addition to those
specified in the proposed AD. Two of those commenters stated that the
corrosion coatings specified in the proposed AD need to be expanded to
include other products typically used in aviation and not just those
identified by Textron. One commenter stated that a carry-thru spar that
has been fully anodized and inspected should be equivalent to or better
than a carry-thru spar with coating applied.
FAA response: The FAA agrees that alternative coating options could
be acceptable. Using the procedures in paragraph (n) of this AD an
owner, operator, or any interested party is welcome to identify an
alternative coating and submit an AMOC request to the FAA along with
substantiating data showing that the proposed AMOC addresses the unsafe
condition with an acceptable level of safety.
M. Requests Regarding Cost Estimates
1. Labor Rate Is Unrealistic
Comment summary: Eight commenters requested the FAA increase the
cost per hour estimates for the labor rate because $85 per work-hour is
too low, does not reflect the true rate of labor, and is not
attainable. One commenter requested that the FAA publish the method
used to derive the hourly rate charged by maintenance shops.
FAA response: The FAA partially agrees with the commenters'
requests. The FAA Office of Aviation Policy and Plans provides the
labor rate of $85 per work-hour to use when estimating the labor costs
of complying with the AD requirements. The FAA does agree to alter the
estimated cost of the eddy current inspection from $85 per work-hour to
a flat rate of $600 for one work-hour of contracted service to more
accurately reflect the cost of eddy current inspection. The FAA revised
the estimated costs and on-conditions costs tables in this AD to
account for the $600 per work-hour contracted service associated with
the eddy current inspection.
2. Estimated Work-Hours
Comment summary: Aviation Plus LLC and several individual
commenters requested that the FAA increase the estimated number of
work-hours for doing the carry-thru spar inspections because the
estimated work-hours specified in the NPRM are too low and do not
include on-condition costs for removing the oxygen systems and air
conditioning systems for access to the inspection area. Two commenters
stated that the costs to remove the airplane interior for access to do
the inspections are not accurate. One commenter wanted to know the
source of the estimated work-hours.
Eleven commenters requested that the proposed estimated cost for
the eddy current inspection be increased and noted that the cost should
include travel time to the grounded airplane or the cost to bring the
eddy current inspector to the airplane.
One of these commenters stated that a flat rate is usually charged
for an eddy current inspection, and four of these commenters stated
that the cost range is usually between $400 and $1,000. The commenters
provided various reasons for their requests.
FAA response: The FAA agrees that some of the estimated costs in
this AD should be revised.
Textron provided the original estimated work-hours for preparing,
inspecting, and reassembling an airplane. The FAA observed inspections
completed by maintenance facilities and verified the personnel were
able to complete the work within the estimates provided by Textron
Aviation. The FAA acknowledges there is variability in the time
necessary to complete the work, depending on a number of factors
including airplane configuration and condition and the experience and
capabilities of the individual(s) performing the work. The cost
estimates provided in the NPRM did not include travel time to the
grounded airplane or the cost to bring the eddy current inspector to
the airplane.
The FAA partially agrees with the commenters' requests and has
increased the estimated work-hours from 12 hours to 20 hours for
removing and reinstalling the interior, removing the foam as
applicable, and preparing the spar for visual and eddy current
inspections. Additionally, in the Estimated costs table in this final
rule the FAA has separated the eddy current inspection of the cap kick
area into a separate line item with an estimate of $600 for contracted
service work-hours and in the On-condition costs table included a line
item for the on-condition eddy current inspection required due to
corrosion or damage with an estimate of $600 for contracted service
work-hours. Furthermore, the FAA added an additional line item that
includes 5 work-hours for airplanes equipped with oxygen bottles and an
additional line item that includes 3 work-hours for airplanes equipped
with air conditioning.
2. Costs of Replacement Parts
Comment summary: Four commenters discussed the availability and
cost of replacement carry-thru spars. The commenters wanted to know how
the FAA determined the estimate of $30,000 for a replacement carry-thru
spar. Another commenter stated that replacement carry-thru spars are
not available from the manufacturer and the cost estimate for a
replacement spar is low. The FAA infers that these commenters are
requesting that the cost estimate for a replacement carry-thru spar be
increased.
FAA's response: Textron provided the $30,000 cost estimate for a
replacement carry-thru spar and has informed the FAA of its intention
to start producing replacement carry-thru spars for Model 177-series
airplanes. Textron is currently producing replacement carry-thru spars
for Model 210-series airplanes, with a current cost of $21,367 for part
number (P/N) 1210721-1 and $19,999 for P/N 2110020-1. The FAA revised
the cost for a replacement carry-thru spar for Model 210-series
airplanes to reflect these actual part costs.
3. Textron Share the Costs
Comment summary: One commenter requested that Textron share the
costs of the inspections. The commenter explained that the corrosion
issue exists because of Textron's carry-thru spar design, which permits
leaking and condensation, and because Textron did not apply anti-
corrosion coatings during manufacture.
FAA response: The FAA has no authority to enforce business
contracts (actual or implied) between parties. The primary concern the
FAA has when issuing an AD is addressing unsafe conditions on various
aircraft flying in the United States. The FAA provides estimated costs
information for complying with the requirements of an AD but does not
control warranty coverage and cannot mandate that a manufacturer cover
all associated costs.
The FAA has not changed the AD in regard to this issue.
N. Requests Regarding Primer and CIC Removal
Comment summary: Ten individual commenters requested that the
proposed AD not require the removal of previously applied primer and
CIC. The commenters stated that removing the previously applied primer
and CIC could damage the carry-thru spar and would result in
duplication of effort, increase in cost, and lack of credit granted for
previous actions.
FAA response: The FAA agrees with the commenters' requests and this
AD does not require removing properly applied primer and CIC that is in
good condition. Paragraph (l) of this AD provides credit for previous
actions, including the application of primer and CIC.
The FAA has not changed this AD in regard to this issue.
O. Request Regarding Spar Structural Capability
Comment summary: One commenter asked how much force is needed to
break a carry-thru spar that does not pass an eddy current inspection.
FAA response: The FAA has no way of knowing precisely how much
force would be required to break a carry-thru spar for which an eddy
current inspection identified a response as detailed in Textron
Aviation Mandatory Service Letters SEL-57-08R2 or SEL-57-09R1. The
residual strength capability of the carry-thru spar is dependent on the
type and amount of damage located on the part, as well as the specific
geometry of the part.
The FAA has not changed this AD in regard to this issue.
P. Requests Regarding Limiting Spar Replacement
Comment summary: Two commenters requested that the FAA only require
carry-thru spar replacement if absolutely necessary. The commenters
explained that replacing a carry-thru spar could introduce additional
safety issues because this action requires disassembling and
reassembling major components, including the airframe, partial fuel and
electrical systems, control systems, and structural repairs. One of the
commenters mentioned that replacement carry-thru spars are difficult to
find.
FAA response: The FAA acknowledges that replacing a carry-thru spar
is a significant and costly effort and could be difficult to find. The
FAA encourages owners, operators, and any interested party to pursue
repair options prior to replacing an affected carry-thru spar and has
provided a means to apply for an AMOC using the procedures provided in
paragraph (n) of this AD. The FAA has not changed this AD in regard to
this
issue.
Q. Requests Regarding Clarifying Minimum Part Thickness
Comment summary: Two individual commenters requested that the
proposed AD specify the minimum acceptable part thickness after a
carry-thru spar is reworked instead of setting a limit on the maximum
amount of material that can be removed during rework. One commenter
stated that the carry-thru spars were not manufactured with tight
tolerances and could be thicker than the specification, allowing for
more material to be removed. The other commenter stated that measuring
the amount of material removed could be difficult if blending was done
over a large area and suggested using data previously released by
Textron that specified thickness limits for various stations along the
spar.
FAA response: The FAA agrees that for Model 210- and 177-series
airplanes, the forged 2014-T6 aluminum carry-thru spars have a wide
range of manufacturing tolerances, both above and below the dimensions
identified in the design data. The FAA also agrees that additional
material, beyond that identified in Table 1 of Textron SEL-57-08R2 and
Textron SEL-57-09R1, may be removed on some spars. However, the amount
of additional material that can be removed varies from one spar to
another and must be evaluated on an individual basis.
The FAA determined that applying the thickness limits identified in
data previously released by Textron for various stations along the spar
must be evaluated on an individual airplane basis, as that information
was not originally developed to address the unsafe condition identified
in this AD. The FAA encourages an owner, operator, or interested party
with a corroded or damaged carry-thru spar that exceed the limits
identified in Table 1 of Textron SEL-57-08R2 and Textron SEL-57-09R1 to
apply for an AMOC using the procedures in paragraph (n) of this AD. The
AMOC request must include substantiating data showing that the proposed
AMOC addresses the unsafe condition with an acceptable level of safety.
The FAA agrees that measuring the amount of material removed may be
challenging and Textron provided suggestions for measuring the amount
of material removed in step 6.B.(8) of the Accomplishment Instructions
in Textron SEL-57-08R2 and Textron SEL-57-09R1. Additional guidance may
be obtained by contacting Textron as detailed in paragraph (n)(3) of
this AD.
The FAA has not changed this AD in regard to this issue.
R. Comment Regarding Reliability Centered Maintenance
Comment summary: One commenter suggested that the FAA find a
solution to address the unsafe condition identified in the NPRM that
promotes reliability centered maintenance (RCM). The commenter
explained that RCM is a concept of maintenance planning to ensure that
systems continue to do what their users require in their present
operating context. Successful implementation of RCM will lead to
increase in cost effectiveness, reliability, machine uptime, and a
greater understanding of the level of risk that the organization is
managing. The commenter stated that blanket ADs cost the general
aviation community millions of dollars but do not increase safety,
instead they increase risk by requiring unnecessary and invasive
maintenance.
FAA response: The FAA lacks sufficient substantiating data to allow
RCM for this AD. An owner, operator, or interested party can request to
use RCM by applying for an AMOC using the procedures in paragraph (n)
of this AD. The AMOC request must include substantiating data showing
that the proposed AMOC addresses the unsafe condition with an
acceptable level of safety.
The FAA has not changed this AD in regard to this issue.
S. Comment Regarding Tubing Corrosion
Comment summary: One commenter stated that the tubing corrosion
issue only applies to a few airplanes rather than the entire fleet. The
commenter did not request a change to the NPRM.
FAA response: Corrosion associated with tubing usually occurs in
the web of the carry-thru spar, and this AD only requires inspecting
the carry-thru spar lower cap. Although this AD does not specifically
apply to corrosion associated with tubing, any corrosion found on the
carry-thru spar lower cap, regardless of origin, is required to be
addressed.
The FAA has not changed this AD in regard to this issue.
Additional Changes to This AD
The FAA did not carry over paragraph (l)(4) from the Credit for
Previous Actions paragraph in the proposed AD into this AD. The FAA did
not take away credit but removed a restriction. In the proposed AD,
paragraph (l)(4) specified that, to receive credit, the protective
coating and CIC had to have been applied to the airplane within 24
months after the date of completing the visual and eddy current
inspection or within 12 months after the effective date of the AD,
whichever occurs first. By the effective date of this final rule many
airplanes will have completed the visual and eddy current inspections
longer than 24 months ago. The airplanes in the applicability of this
AD are not as likely to develop corrosion as the Model 210G through
Model 210M airplanes that were included in the applicability of AD
2020-03-16 (the immediately adopted rule discussed previously), so the
FAA determined that the requirement of corrosion application within 24
months after the visual and eddy current inspections was not necessary.
The FAA did not want to penalize operators who had already completed
the eddy current inspection by requiring they do the inspection again
because they were outside of the 24-month limit. However, the
requirement in paragraph (i) of this AD that CIC must be applied within
12 months after the effective date of this AD is unchanged.
Paragraph (h) of the proposed AD did not have explicit compliance
times for completing the eddy current inspections, relying on paragraph
(g) for the applicable compliance times for the eddy current
inspections. For clarity, paragraph (h) now points to paragraph (g) for
compliance times.
Conclusion
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for the changes discussed
previously, omitting the Paperwork Reduction Act Burden Statement,
paragraph (n) in the proposed AD, and reidentifying the subsequent
paragraphs, this AD is adopted as proposed in the NPRM. None of the
changes will increase the economic burden on any operator.
Related Service Information Under 1 CFR Part 51
The FAA reviewed the following service documents:
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, Revision 2, dated August 3, 2020 (Textron SEL-57-08R2); and
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-09, Revision 1, dated August 3, 2020 (Textron SEL-57-09R1).
For the applicable airplanes specified, these service letters
contain instructions for visually inspecting the carry-thru spar for
corrosion, damage, and cracking and for completing an eddy current
inspection. This service information also specifies applying protective
coating and CIC.
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in the ADDRESSES section.
Other Related Service Information
The FAA reviewed the following service letters related to this AD
which, for the applicable airplanes specified, contain instructions for
visually inspecting the carry-thru spar for corrosion and doing an eddy
current inspection of the carry-thru spar regardless of whether
corrosion was found and removed. This service information also contains
instructions for applying CIC, but does not specify applying protective
coating.
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-06, dated June 24, 2019 (Textron SEL-57-06);
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-06, Revision 1, dated November 19, 2019;
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-07, dated June 24, 2019 (Textron SEL-57-07); and
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-07, Revision 1, dated November 19, 2019.
The FAA also reviewed the service letters listed below related to
this AD, which, for the applicable airplanes specified, contain the
same instructions and repair criteria as Textron SEL-57-08R2 and
Textron SEL-57-09R1.
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, dated November 1, 2019;
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-08, Revision 1, dated November 19, 2019; and
Textron Aviation Mandatory Single Engine Service Letter,
SEL-57-09, dated November 19, 2019.
Differences Between This AD and the Service Information
Although Textron SEL-57-08R2 also applies to Models 210G,
T210G, 210H, T210H, 210J, T210J, 210K, T210K, 210L, T210L, 210M, and
T210M airplanes, this AD does not. The FAA issued AD 2020-03-16 to
address the immediate safety of flight for those airplanes.
Textron SEL-57-08R2 and Textron SEL-57-09R1 specify
inspecting all interior surfaces of the carry-thru spar; additionally,
Textron SEL-57-09R1 specifies inspecting the lower surface of the
outboard spar to wing attach lugs. This AD only requires inspecting the
carry-thru spar lower cap, including the lower surface, edge, and upper
surface of the lower cap. While the web, upper cap, and lugs of the
carry-thru spar may be susceptible to corrosion, evidence does not
support including inspection of these areas as part of this AD. The FAA
will continue to monitor reports of corrosion on all areas of the
carry-thru spar for potential future action.
Textron SEL-57-08R2 and Textron SEL-57-09R1 do not specify
an eddy current inspection on the carry-thru spar unless the amount of
material removed in the blended area exceeds 0.010-inch deep but is
within limits. This AD requires an eddy current inspection of all
locations on the carry-thru spar lower cap where corrosion was removed.
The fatigue crack on the Model T210M airplane that suffered the fatal
in-flight break-up initiated from a corrosion pit approximately 0.011-
inch deep in the lower cap kick area. The visual and less restrictive
eddy current inspection requirements specified in Textron SEL-57-08R2
and Textron SEL-57-09R1 could miss similar fatigue cracking on
airplanes currently operating in the field.
Textron SEL-57-08R2 and Textron SEL-57-09R1 only specify
an eddy current inspection of the lower cap kick of the carry-thru spar
if corrosion is identified on the carry-thru spar cap. This AD requires
a one-time eddy current inspection of the lower cap kick area of all
affected airplanes, regardless of the results of the visual inspection.
The fatigue crack on the Model T210M airplane that suffered the fatal
in-flight break-up initiated in the lower cap kick area. Cracking and
corrosion damage may be difficult to identify through visual inspection
alone. The FAA will use the results of the one-time eddy current
inspection of the lower cap kick area, in part, to determine the
necessity of future rulemaking action.
Textron SEL-57-08R2 and Textron SEL-57-09R1 specify
contacting Textron for evaluation and disposition of certain damage.
Instead, this AD requires removing the carry-thru spar from service or
repairing it (if possible) in accordance with the AMOC procedures
identified in paragraph (n) of this AD. Operators should work with
Textron to develop a repair in support of an AMOC request.
Textron SEL-57-08 R2 and Textron SEL-57-09R1 provide
instruction allowing airplanes that have complied with Textron SEL-57-
06 or Textron SEL-57-07 to complete the application of the protective
coating and CIC within 200 flight hours or at the next annual
inspection, whichever occurs first. This AD permits applying protective
coating and CIC within 12 months after the effective date of this AD.
Interim Action
The FAA considers this AD to be an interim action. This AD requires
one-time visual and eddy current inspections of the carry-thru spar
lower cap for corrosion, cracking, and damage, corrective action if
necessary, applying a protective coating and CIC, and reporting the
inspection results to the FAA. The FAA will analyze the inspection
results received to determine further rulemaking action.
Costs of Compliance
The FAA estimates that this AD affects 3,421 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
| Action |
Labor cost |
Parts cost |
Cost per airplane |
Cost on U.S. operators |
| Inspection (includes part removal
for access, removal of foam, if required, visual inspection, and reassembly) |
20 work-hours x $85
per hour = $1,700 |
Not applicable |
$1,700 |
$5,815,700 |
| Eddy current inspection of the
cap kick area |
1 work-hour contracted
service x $600 =
$600 |
Not applicable |
600 |
$2,052,600 |
| Spar treatment (primer and corrosion
inhibitor) * |
3.50 work-hours x $85
per hour = $297.50 |
$340 |
637.50 |
$2,180,887.50 |
| Removal and reinstallation of
oxygen bottles **
|
5 work-hours x $85
per hour = $425 |
Not applicable |
425 |
Up to $1,453,925 (not
all airplanes have oxygen bottles installed) |
| Removal and reinstallation of
air conditioning components
** |
3 work-hours x $85
per hour = $255 |
Not applicable |
255 |
Up to $872,355 (not
all airplanes have air conditioning installed) |
| Reporting requirement |
2 work-hours x $85
per hour = $170 |
Not applicable |
170 |
$581,570 |
* Model 210-series airplanes may
only require application of corrosion inhibitor, depending on the condition
of
the zinc chromate primer. Model 177-series airplanes may or may not require
application of the primer,
depending on the production year and the quality of any existing zinc
chromate primer.
** Some Model 210-series airplanes are equipped with oxygen bottles in
the area of the carry-thru spar. Some
Model 210- and 177-series airplanes are equipped with air conditioning
systems. Additional work-hours were
included in the estimated costs to account for the additional time required
to complete the AD requirements on
these airplanes.
The FAA estimates the following costs to do any necessary repairs
or replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
aircraft that might need these actions:
On-Condition Costs
| Action |
Labor cost |
Parts cost |
Cost per product |
| Corrosion removal |
2 work-hours x $85 per hour =
$170 |
Not applicable |
$170 |
| On-condition eddy current inspection |
1 work-hour contracted service
x $600 = $600 |
Not applicable |
600 |
| Spar replacement-Model 210/T210-airplanes
(P/N 1210721-1) |
160 work-hours x $85 per hour
= $13,600 |
$21,367 |
34,967 |
| Spar replacement-Model 210/T210-airplanes
(P/N 2110020-1) |
160 work-hours x $85 per hour
= $13,600 |
$19,999 |
33,599 |
| Spar replacement-Model P210 airplane |
220 work-hours x $85 per hour
= $18,700 |
$19,999 |
38,699 |
| Spar replacement-Model 177-series
airplane |
120 work-hours x $85 per hour
= $10,200 |
$30,000 |
40,200 |
The amount of work-hours necessary
to complete the eddy current
inspection and corrosion removal will depend on the extent of the
corrosion on the carry-thru spar. The FAA has no way of estimating the
work-hours that may be required for those procedures. The FAA's cost
estimate assumes a minimum of one hour contracted service for the eddy
current inspection and two hours for the corrosion removal. If the
operator needs an AMOC for repair, the FAA has no way of estimating the
extent of damage or follow-on eddy current inspection that may be
required. The FAA has no way of estimating the potential cost of those
actions.
Replacement carry-thru spars are not currently available from
Textron for Model 177-series airplanes. Textron no longer produces the
current carry-thru spar design and is developing a new design. The FAA
does not have data to determine the availability of replacement carry-
thru spars from other sources.
Paperwork Reduction Act
A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to a penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a currently valid OMB Control Number. The OMB
Control Number for this information collection is 2120-0056. Public
reporting for this collection of information is estimated to take
approximately 1 hour per response, including the time for reviewing
instructions, searching existing data sources, gathering and
maintaining the data needed, and completing and reviewing the
collection of information. All responses to this collection of
information are mandatory. Send comments regarding this burden estimate
or any other aspect of this collection of information, including
suggestions for reducing this burden to: Information Collection
Clearance Officer, Federal Aviation Administration, 10101 Hillwood
Parkway, Fort Worth, TX 76177-1524.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
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