| preamble attached >>> |
ADs updated daily at www.Tdata.com
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| PROPOSED AD |
BOEING:
Docket No. FAA-2008-0415; Directorate Identifier 2007-NM-256-AD.
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COMMENTS DUE DATE
(a) We must receive comments by June 12, 2008.
AFFECTED ADS
(b) None.
APPLICABILITY
(c) This AD applies to Boeing airplanes identified in Table 1 of this AD,
certificated in any category.
TABLE 1.--APPLICABILITY
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AS IDENTIFIED IN BOEING ALERT
BOEING MODEL-- SERVICE BULLETIN--
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(1) 737-100, -200, -200C, -300, -400, 737-27A1278, dated May 24, 2007.
and -500 series airplanes.
(2) 737-600, -700, -700C, -800, -900, 737-27A1277, Revision 1, dated
and -900ER series airplanes. July 25, 2007.
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UNSAFE CONDITION
(d) This AD results from a report of extensive corrosion of a ballscrew in
the drive mechanism of the horizontal stabilizer trim actuator (HSTA).
We are issuing this AD to prevent an undetected failure of the primary
load path for the ballscrew in the drive mechanism of the HSTA and
subsequent wear and failure of the secondary load path, which could
lead to loss of control of the horizontal stabilizer and consequent
loss of control of the airplane.
COMPLIANCE
(e) Comply with this AD within the compliance times specified, unless
already done.
SERVICE BULLETINS
(f) The term "service bulletin," as used in this AD, means the applicable
service bulletins specified in Table 2 of this AD.
TABLE 2.--SERVICE BULLETINS
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BOEING ALERT SERVICE BULLETIN-- FOR MODEL--
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(1) 737-27A1278, dated May 24, 2007. 737-100, -200, -200C, -300, -400,
and -500 series airplanes.
(2) 737-27A1277, Revision 1, dated 737-600, -700, -700C, -800, -900,
July 25, 2007. and -900ER series airplanes.
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NOTE 1: The service bulletins refer to UMBRA CUSCINETTI Service Bulletin
07322-27-01, dated December 21, 2004; Linear Motion Service Bulletin
7901708, Revision A, dated July 26, 2005; Boeing 737 Service Bulletin 27
-1046, Revision 1, dated April 5, 1974; and/or SKYTRONICS Service Bulletin
93004, dated September 1, 2005, as applicable, as additional sources of
service information for accomplishing the specified actions.
INSPECTIONS, LUBRICATIONS, REPAIRS/OVERHAULS, AND APPLICABLE CORRECTIVE
ACTIONS
(g) At the applicable compliance time and repeat intervals listed in
Tables 1 and 2 of paragraph 1.E., "Compliance," of the service
bulletin, do the inspections, lubrications, repairs/overhauls,
installation(s), and applicable corrective actions by accomplishing
all the applicable actions specified in the Accomplishment
Instructions of the service bulletin; except as provided by paragraphs
(g)(1) through (g)(3) of this AD.
(1) Where paragraph 1.E., "Compliance," of the service bulletin specifies
an initial compliance time for accomplishing the initial inspection,
lubrication, or repair/overhaul, this AD requires doing the applicable
initial action(s) at the later of the times specified in paragraphs
(g)(1)(i) and (g)(1)(ii) of this AD.
(i) At the applicable compliance time specified in paragraph 1.E., "Comp-
liance," of the service bulletin.
(ii) Within the applicable compliance time specified in paragraph
(g)(1)(ii)(A), (g)(1)(ii)(B), or (g)(1)(ii)(C) of this AD.
(A) For the initial detailed inspection and lubrication: Within 6 months
after the effective date of this AD.
(B) For the initial repair/overhaul: Within 12 months after the effective
date of this AD.
(C) For the installation(s): Within 12 months after the effective date of
this AD.
(2) Where Table 2 of paragraph 1.E., "Compliance," of Boeing Alert Service
Bulletin 737-27A1277, Revision 1, dated July 25, 2007, specifies a
compliance time of "* * * within 25,000 Flight Hours since the latest
horizontal stabilizer trim actuator (HSTA) Overhaul from the date of
Revision 1 of this Service Bulletin * * *," this AD requires
compliance "* * * within 25,000 flight hours since the last overhaul
of the trim actuator of the horizontal stabilizer."
(3) Where Work Package 4, paragraphs 1.a., 2.a., and 3.a., of the Accomp-
lishment Instructions of Boeing Alert Service Bulletin 737-27A1278,
dated May 24, 2007, specifies to identify the HSTA name plate "* * *
AS GIVEN IN SB 737-27A1278, WORK PACKAGE 3," this AD requires that
identification " * * * AS GIVEN IN SB 737-27A1278, WORK PACKAGE 4."
(4) Where Note (b) of Figures 7 through 9 of Boeing Alert Service Bulletin
737-27A1278, dated May 24, 2007, specifies to do a "* * * Backlash
Inspection as given in AMM 27-41-81/606," this AD requires an "* * *
End Play Test as given in OHM 27-45-11 page 701."
(h) Actions done before the effective date of this AD in accordance with
Boeing Alert Service Bulletin 737-27A1277, dated July 21, 2005, are
acceptable for compliance with the corresponding requirements of this
AD.
ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)
(i)(1) The Manager, Seattle Aircraft Certification Office, FAA, ATTN:
Kelly McGuckin, Aerospace Engineer, Systems and Equipment Branch,
ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917
-6490; fax (425) 917-6590; has the authority to approve AMOCs for
this AD, if requested using the procedures found in 14 CFR 39.19.
(2) To request a different method of compliance or a different compliance
time for this AD, follow the procedures in 14 CFR 39.19. Before using
any approved AMOC on any airplane to which the AMOC applies, notify
your appropriate principal inspector (PI) in the FAA Flight Standards
District Office (FSDO), or lacking a PI, your local FSDO.
Issued in Renton, Washington, on April 17, 2008. Ali Bahrami, Manager,
Transport Airplane Directorate, Aircraft Certification Service.
DATES: We must receive comments on this proposed AD by June 12, 2008.
| PREAMBLE |
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DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
14 CFR Part 39
[Docket No. FAA-2008-0415; Directorate Identifier 2007-NM-256-AD] RIN
2120-AA64
AIRWORTHINESS DIRECTIVES; Boeing Model 737 Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Boeing Model 737 airplanes. This proposed AD would require
repetitive inspections, lubrications, and repetitive repairs/overhauls of
the ball nut and ballscrew and attachment (Gimbal) fittings for the trim
actuator of the horizontal stabilizer; various installation(s); and
corrective actions if necessary; as applicable. This proposed AD results
from a report of extensive corrosion of a ballscrew used in the drive
mechanism of the horizontal stabilizer trim actuator (HSTA). We are
proposing this AD to prevent an undetected failure of the primary load
path for the ballscrew in the drive mechanism of the HSTA and subsequent
wear and failure of the secondary load path, which could lead to loss of
control of the horizontal stabilizer and consequent loss of control of the
airplane.
DATES: We must receive comments on this proposed AD by June 12, 2008.
ADDRESSES: You may send comments by any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket Operations, M-30, West
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE.,
Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30,
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE.,
Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
For service information identified in this AD, contact Boeing Commercial
Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
EXAMINING THE AD DOCKET
You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
The AD docket contains this proposed AD, the regulatory evaluation, any
comments received, and other information. The street address for the
Docket Office (telephone 800-647-5527) is in the ADDRESSES section.
Comments will be available in the AD docket shortly after receipt.
FOR FURTHER INFORMATION CONTACT: Kelly McGuckin, Aerospace Engineer, Sys-
tems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone
(425) 917-6490; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
COMMENTS INVITED
We invite you to send any written relevant data, views, or arguments about
this proposed AD. Send your comments to an address listed under the
ADDRESSES section. Include "Docket No. FAA-2008-0415; Directorate
Identifier 2007-NM-256-AD" at the beginning of your comments. We
specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of this proposed AD. We will consider
all comments received by the closing date and may amend this proposed AD
because of those comments.
We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.
DISCUSSION
On January 31, 2000, there was an accident involving a McDonnell Douglas
Model DC-9-83 (MD-83) airplane. The National Transportation Safety Board
(NTSB) determined that the probable cause of the accident was a loss of
airplane pitch control resulting from the in-flight failure of the acme
nut threads of the jackscrew assembly of the horizontal stabilizer trim
system. The NTSB concluded that the thread failure was caused by excessive
wear, resulting from insufficient lubrication of the jackscrew assembly.
The drive mechanism of the horizontal stabilizer on Model MD-83 airplanes
has a jackscrew assembly with an acme screw. The drive mechanism of the
horizontal stabilizer on Boeing Model 737 airplanes has a horizontal
stabilizer trim actuator (HSTA) with a ballscrew. Acme screws and
ballscrews have some differences in design, but perform similar functions
and have the same airplane-level effect following failure.
In response to this accident, Boeing initiated a design review and safety
analysis of the primary and secondary load paths of the ballscrew assembly
used on the HSTA of their airplanes. During this review, one operator of a
Model 757 airplane reported extensive corrosion of a ballscrew assembly of
the HSTA. Investigation revealed extensive corrosion of the primary load
path ball bearings in the ballscrew assembly. This condition, if not
corrected, could result in an undetected failure of the primary load path
for the ballscrew in the drive mechanism of the HSTA and subsequent wear
and failure of the secondary load path, which could lead to loss of
control of the horizontal stabilizer and consequent loss of control of the
airplane.
The ballscrew assembly on Model 757 airplanes is similar to those on the
affected Model 737 airplanes. Therefore, all of these models may be
subject to the same unsafe condition.
OTHER RELEVANT RULEMAKING
We are considering additional rulemaking to address the identified unsafe
condition on Model 757 airplanes.
RELEVANT SERVICE INFORMATION
We have reviewed the following Boeing Service Bulletins:
TABLE--PRIMARY SERVICE BULLETINS
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DESCRIBES THE
FOLLOWING PROCEDURES
FOR THE TRIM
ACTUATOR OF THE AND RECOMMENDS THAT
BOEING ALERT SERVICE HORIZONTAL THOSE ACTIONS BE
BULLETIN-- STABILIZER DONE--
(DEPENDING ON THE
AIRPLANE
CONFIGURATION)--
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737-27A1277, Revision 1, Repetitive detailed Within 6,400 flight
dated July 25, 2007 (for and general visual hours or 18 months
Model 737-600, -700, -700C, inspections to from the last
-800, -900, and -900ER detect detailed
series airplanes). discrepancies inspection,
(e.g., metal whichever occurs
particles or first, and
corrosion in thereafter at
grease, damage, intervals not to
cracks, corrosion, exceed 6,400 flight
worn areas, grease hours or 2 years,
leakage, and loose whichever occurs
ball bearings) of first.
the ball nut and
ballscrew.
Repetitive Within 1,600 flight
lubrications of the hours or 1 year
ball nut and from the last
ballscrew. lubrication,
whichever occurs
first, and
thereafter at
intervals not to
exceed 1,600 flight
hours or 1 year,
whichever occurs
first.
Repetitive repair/ Before the
overhaul. accumulation of
25,000 flight hours
since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 25,000
flight hours since
the last overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
first, and
thereafter at
intervals not to
exceed 25,000
flight hours.
Installation of tube Before the
retainers on the accumulation of
ball nut. 25,000 flight hours
since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 25,000
flight hours since
the latest overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
later.
Applicable Before further
corrective actions. flight.
The corrective
actions include
repairing/replacing
discrepant parts.
737-27A1278, dated May 24, Repetitive detailed Within 2,000 or
2007 (for Model 737-100, - and general visual 4,000 flight hours
200, -200C, -300, -400, and inspections to or 12 or 18 months
-500 series airplanes). detect from the last
discrepancies detailed
(e.g., metal inspection,
particles or whichever occurs
corrosion in first, and
grease, damage, thereafter at
cracks, corrosion, intervals not to
worn areas, grease exceed 2,000 or
leakage, and loose 4,000 flight hours
ball bearings) of or 1 or 2 years,
the ball nut and whichever occurs
ballscrew and first (depending on
attachment (Gimbal) the airplane
fittings. configuration).
Repetitive Within 500 or 2,000
lubrications of the flight hours or 2
ball nut and months or 1 year
ballscrew and from the last
attachment (Gimbal) lubrication,
fittings. whichever occurs
first, and
thereafter at
intervals not to
exceed 500 or 2,000
flight hours or 2
months or 1 year,
whichever occurs
first (depending on
the airplane
configuration).
Repetitive repair/ Before the
overhaul. accumulation of
20,000 flight hours
or 24,000 flight
hours since the
date of issuance of
the original
standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 20,000
flight hours or
24,000 flight hours
since the last
overhaul of the
trim actuator of
the horizontal
stabilizer,
whichever occurs
first (depending on
the airplane
configuration); and
thereafter at
intervals not to
exceed 20,000 or
25,000 flight
cycles (depending
on the airplane
configuration).
Installation of tube Before the
retainers on the accumulation of
ball nut. 24,000 flight hours
since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 24,000
flight hours since
the last overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
first.
Installation of a Before the
grease fitting. accumulation of
20,000 flight hours
since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 20,000
flight hours since
the last overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
first.
Installation of new Before the
ball deflectors and accumulation of
guide clamps for 24,000 flight hours
the ball return. since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 24,000
flight hours since
the last overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
first.
Installation of new Before the
return tube clamps. accumulation of
20,000 flight hours
since the date of
issuance of the
original standard
airworthiness
certificate or the
date of issuance of
the original export
certificate of
airworthiness, or
within 20,000
flight hours since
the last overhaul
of the trim
actuator of the
horizontal
stabilizer,
whichever occurs
first.
Applicable Before further
corrective actions. flight.
The corrective
actions include
repairing/replacing
discrepant parts.
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TABLE.--SECONDARY SERVICE BULLETINS
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BOEING ALERT SERVICE BULLETIN-- REFERS TO--
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737-27A1277, Revision 1, dated July 25, UMBRA CUSCINETTI Service
2007 (for Model 737-600, -700, -700C, - Bulletin 07322-27-01, dated
800, -900, and -900ER series December 21, 2004, as an
airplanes). additional source of service
information for installing
tube retainers on the ball
nut.
737-27A1278, dated May 24, 2007 (for UMBRA CUSCINETTI Service
Model 737-100, -200, -200C, -300, - Bulletin 07322-27-01, dated
400, and -500 series airplanes). December 21, 2004, as an
additional source of service
information for installing
tube retainers on the ball
nut.
Boeing 737 Service Bulletin 27-
1046, Revision 1, dated April
5, 1974, as an additional
source of service information
for installing a grease
fitting.
Linear Motion Service Bulletin
7901708, Revision A, dated
July 26, 2005, as an
additional source of service
information for installing new
ball deflectors and guide
clamps for the ball return.
SKYTRONICS Service Bulletin
93004, dated September 1,
2005, as an additional source
of service information for
installing new return tube
clamps.
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FAA'S DETERMINATION AND REQUIREMENTS OF THIS PROPOSED AD
We are proposing this AD because we evaluated all relevant information and
determined the unsafe condition described previously is likely to exist or
develop in other products of the(se) same type design(s). This proposed AD
would require accomplishing the actions specified in the primary service
bulletins described previously.
CLARIFICATION OF APPLICABILITY OF THIS AD
Boeing has informed us that Model 737-900ER series airplanes were not
specifically identified by model name in the Effectivity section of Boeing
Alert Service Bulletin 737-27A1277. However, those airplanes are
identified by variable numbers in the Effectivity section. Therefore, this
AD refers to Model 737-900ER series airplanes where appropriate.
COSTS OF COMPLIANCE
We estimate that this proposed AD would affect 1,602 Model 737 airplanes
of U.S. registry. The following table provides the estimated costs for
U.S. operators to comply with this proposed AD.
ESTIMATED COSTS
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AVERAGE NUMBER OF
WORK LABOR U.S.-
ACTION HOURS RATE COST PER REGISTERED FLEET
\1\ \1\ PER PARTS PRODUCT \1\ AIRPLANES COST \1\
HOUR
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Detailed
inspect-
ions... 2 or 4.. $80 None $160 or $320, 1,602 Between $256,320,
per inspect- and $512,640 per
ion cycle. inspection cycle.
Lubricat-
ions.. 1 or 3.. 80 None $80 or $240, 1,602 Between $128,160,
per lubricat- and $384,480 per
ion cycle. lubrication cycle.
Repairs/
overhauls. 40...... 80 None $3,200 per 1,602 $5,126,400 per
repair/over- repair/overhaul
haul. cycle.
Installat- Between
ions. 1 and 3. 80 $2,200 Between $2,280 1,320 Between $3,009,600
and $2,440 and $3,220,800.
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\1\ Depending on airplane configuration.
The number of work hours, as indicated above, is presented as if the
accomplishment of the actions in this proposed AD is to be conducted as
new "stand alone" actions. However, in actual practice, the lubrications,
detailed inspections, and overhauls are currently being done as part of
normal airplane maintenance. The repair can be done coincidentally or in
combination with the normally scheduled HSTA and ballscrew overhaul.
Therefore, the actual number of necessary additional work hours will be
minimal in many instances. Additionally, any costs associated with special
airplane scheduling will be minimal.
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.
We are 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
We determined that this proposed AD would not have federalism implications
under Executive Order 13132. This proposed AD would 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 this proposed regulation:
1. Is not a "significant regulatory action" under Executive Order 12866,
2. Is not a "significant rule" under the DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979), 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.
You can find our regulatory evaluation and the estimated costs of
compliance in the AD Docket.
LIST OF SUBJECTS IN 14 CFR PART 39
Air transportation, Aircraft, Aviation safety, Safety.
THE PROPOSED AMENDMENT
Accordingly, under the authority delegated to me by the Administrator, the
FAA proposes to amend 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 AD: