DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
14 CFR Part 39
[Docket No. FAA-2008-0442, Directorate Identifier 2007-SW-24-AD] RIN 2120
-AA64
AIRWORTHINESS DIRECTIVES; Sikorsky Aircraft Corporation Model S-61A, D, E,
L, N, NM, R, and V; Croman Corporation Model SH-3H, Carson Helicopters,
Inc. Model S-61L; Glacier Helicopter Model CH-3E; Robinson AirCrane, Inc.
Model CH-3E, CH-3C, HH-3C and HH-3E; and Siller Helicopters Model CH-3E
and SH-3A Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This amendment proposes superseding an existing airworthiness
directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-61A,
D, E, L, N, NM, R, and V helicopters. The existing AD currently requires
determining whether the main rotor shaft (MRS) was used in repetitive
external lift (REL) operations. The existing AD also requires a
nondestructive inspection (NDI) for cracks, replacing any unairworthy MRS
with an airworthy MRS, appropriately marking the MRS, making a logbook
entry, and establishing retirement lives for each REL MRS. This proposed
AD would contain some of the same requirements but would determine new
retirement lives for each MRS. The REL retirement life would be based on
hours time-in-service (TIS) or lift cycles, whichever occurs first. The
Non-REL retirement life would be reduced and would only be based on hours
TIS. This proposed AD would also require the operator to remove from
service any MRS with oversized dowel pin bores. Also, certain restricted
category models that were inadvertently omitted in the current AD would be
added to the applicability. This proposed AD is prompted by the
manufacturer's reevaluation of the retirement life for the MRS based on
torque, ground-air-ground (GAG) cycle, and fatigue testing. The actions
specified by the proposed AD are intended to prevent MRS structural
failure, loss of power to the main rotor, and subsequent loss of control
of the helicopter.
DATES: Comments must be received on or before June 23, 2008.
ADDRESSES: Use one of the following addresses to submit comments on this
proposed AD:
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.
You may get the service information identified in this proposed AD from
Sikorsky Aircraft Corporation, Attn: Manager, Commercial Tech Support,
6900 Main Street, Stratford, Connecticut 06614, phone (203) 386-3001, fax
(203) 386-5983.
You may examine the comments to this proposed AD in the AD docket on the
Internet at http://www.regulations.gov.
FOR FURTHER INFORMATION CONTACT: Jeffrey Lee, Aviation Safety Engineer,
Boston Aircraft Certification Office, 12 New England Executive Park,
Burlington, MA 01803, telephone (781) 238-7161, fax (781) 238-7170.
SUPPLEMENTARY INFORMATION:
COMMENTS INVITED
We invite you to submit any written data, views, or arguments regarding
this proposed AD. Send your comments to the address listed under the
caption ADDRESSES. Include the docket number "FAA-2008-0442, Directorate
Identifier 2007-SW-24-AD" at the beginning of your comments. We
specifically invite comments on the overall regulatory, economic,
environmental, and energy aspects of the proposed AD. We will consider all
comments received by the closing date and may amend the proposed AD in
light 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 with
FAA personnel concerning this proposed rulemaking. Using the search
function of the docket Web site, you can find and read the comments to any
of our dockets, including the name of the individual who sent or signed
the comment. You may review the DOT's complete Privacy Act Statement in
the Federal Register published on April 11, 2000 (65 FR 19477-78).
EXAMINING THE DOCKET
You may examine the docket that contains the proposed AD, any comments,
and other information in person at the Docket Operations office between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The
Docket Operations office (telephone (800) 647-5527) is located in Room
W12-140 on the ground floor of the West Building at the street address
stated in the ADDRESSES section. Comments will be available in the AD
docket shortly after receipt.
DISCUSSION
In 1995 a Model S-58T helicopter lost transmission drive due to fatigue
cracking on the MRS flange connection. Due to similarities between the
Model S-58T and the S-61 MRS drive connection, Sikorsky conducted a review
of the Model S-61 MRS cracking history. This review identified similar
fatigue cracking mode origins in similar locations in both the Model S-61
and the S-58T MRS.
On December 7, 1998, the FAA issued AD 98-26-02, Amendment 39-10943 (63 FR
69177), Docket No. 96-SW-29-AD, for Sikorsky Model S-61A, D, E, L, N, NM,
R, and V helicopters. AD 98-26-02 requires an NDI for cracks, replacing
any unairworthy MRS with an airworthy MRS, appropriately marking the MRS
by following Sikorsky Alert Service Bulletin (ASB) 61B35-68, dated July
19, 1996, and making logbook entries. AD 98-26-02 also establishes
retirement lives of 1,500 hours TIS for unmodified MRS assemblies used in
REL operations and 2,200 hours TIS for modified MRS assemblies used in REL
operations. That action was prompted by four reports of cracks in
helicopter MRSs used in REL operations. That condition, if not corrected,
could result in MRS structural failure, loss of power to the main rotor,
and subsequent loss of control of the helicopter.
Since issuing AD 98-26-02, an investigation of REL operations revealed the
REL mission profile parameters have changed significantly from those
previously used to calculate the MRS retirement lives. The original MRS
was certified by analysis in shaft bending only. Due to the service
history, Sikorsky performed fatigue testing with Torque GAG cycles for
both REL and Non-REL spectrums. The results of the fatigue testing with
torque GAG cycles prompted changes in certain life limits. This
information has led to the need for new retirement criteria for MRSs used
in both REL and non-REL operations.
Sikorsky has issued Customer Service Notice (CSN) No. 6135-10A and
Sikorsky Service Bulletin (SB) No. 61B35-53A, both dated April 19, 2004.
The CSN and the SB apply to Model S-61L, N, and NM (serial number (S/N)
61454), and R series transport category helicopters; and S-61A, D, E, and
V series restricted category helicopters. The CSN specifies replacing the
planetary assembly and MRS assembly attaching hardware with high strength
hardware. The CSN also specifies reworking the dowel retainer to increase
hole chamfer and related countersink diameters. The SB specifies replacing
the existing planetary matching plates with new steel matching plates
during overhaul at the operator's discretion.
Also, Sikorsky has issued ASB No. 61B35-69, dated April 19, 2004 (ASB
61B35-69), which supersedes ASB 61B35-68B. ASB 61B35-69 provides updated
procedures for determining REL and Non-REL status, assigns new REL and
Non-REL MRS retirement lives, and provides a method for marking the REL
MRS.
We have identified an unsafe condition that is likely to exist or develop
on other Sikorsky model helicopters of these same type designs. Therefore,
the proposed AD would supersede AD 98-26-02 to require the following:
Within 10 hours TIS for certain part-numbered MRSs:
- Create a component history card or equivalent record.
- Count and, at the end of each day's operations, record the number of
external lift cycles (lift cycles) performed and the hours TIS. An
external lift cycle is defined as a flight cycle in which an external
load is picked up, the helicopter is repositioned (through flight or
hover), and the helicopter hovers and releases the load and departs or
lands and departs.
- If you do not have records of hours TIS on an individual MRS, substitute
helicopter hours TIS.
Determine whether the MRS is an REL or Non-REL MRS by using a 250-hour TIS
moving average.
- Upon reaching 250 hours TIS, calculate the first moving average of lift
cycles. If the calculation results in more than 6 lift cycles per hour
TIS, the MRS is an REL MRS. If the calculation results in 6 or less lift
cycles per hour TIS, the MRS is a Non-REL MRS. If you know only a
portion of the number of the lift cycles during the previous 250 hours
TIS, add that known number to a number calculated by multiplying the
number of hours TIS for which you do not know the lift cycles by a
factor of 30 to arrive at the accumulated number of lift cycles.
- If you determine the MRS is a Non-REL MRS based on the previous
calculation of the 250-hour TIS moving average for lift cycles,
thereafter at intervals of 50 hour TIS, recalculate the average lift
cycles per hour TIS. If the calculation results in more than 6 lift
cycles per hour TIS, the MRS is an REL MRS. If the calculation results
in 6 or less lift cycles per hour TIS, the MRS is a Non-REL MRS. If you
know only a portion of the number of the lift cycles during the next
interval of 50 hours TIS, add that known number to a number calculated
by multiplying the number of hours TIS for which you do not know the
lift cycles by a factor of 30 to arrive at the accumulated number of
lift cycles for that interval.
- Once an MRS is determined to be an REL MRS, you no longer need to
perform the 250-hour TIS moving average calculation, but you must
continue to count and record the lift cycles and number of hours TIS.
Within 5 hours TIS after determining the MRS is an REL MRS, identify it as
an REL MRS by etching "REL" on the outside diameter of the MRS near the
part serial number.
If an MRS is determined to be an REL MRS, it remains an REL MRS for the
rest of its service life and is subject to the retirement times for an REL
MRS.
For each REL MRS, within 1,100 hours TIS, conduct an NDI for cracks in the
MRS. If a crack is found, replace it with an airworthy MRS before further
flight.
Replace each MRS with an airworthy MRS on or before reaching the revised
retirement life as follows:
- For an REL MRS that is not modified (unmodified REL MRS); establish a
retirement life of 30,000 lift cycles or 1,500 hours TIS, whichever
occurs first. Replace it on or before accumulating 30,000 lift cycles or
1,500 hours TIS, whichever comes first. For an unmodified REL MRS
installed on a helicopter on the effective date of this AD that has
accumulated more than 30,000 lift cycles or 1,350 hours TIS, replace it
within 150 hours TIS or upon removal, whichever occurs first.
- For an REL MRS that is modified; establish a retirement life of 30,000
lift cycles or 5,000 hours TIS, whichever occurs first. Replace it on or
before accumulating 30,000 lift cycles or 5,000 hours TIS, whichever
comes first. For modified REL MRS installed on a helicopter on the
effective date of this AD that has accumulated more than 30,000 lift
cycles or 4,500 hours TIS, replace it within 500 hours TIS or upon
removal, whichever occurs first.
- For a Non-REL MRS, reduce the retirement life to 13,000 hours TIS. For a
Non-REL MRS installed on a helicopter on the effective date of this AD
that has accumulated more than 11,500 but less than 40,500 hours TIS,
replace it within 1,500 hours TIS, or upon removal, whichever occurs
first.
Record the revised retirement life on the MRS component history card or
equivalent record.
Within 50 hours TIS, remove from service any MRS with oversized (0.8860"
or greater) dowel pin bores.
DO THE ACTIONS BY FOLLOWING THE SPECIFIED PORTIONS OF THE SERVICE
INFORMATION DESCRIBED PREVIOUSLY.
We estimate that this proposed AD would affect 60 helicopters of U.S.
registry, and the NDI inspection, remarking, and replacing an MRS would
take about 2.2 work hours per helicopter at an average labor rate of $80
per work hour. Required parts would cost about $50 for the supplies
required for the NDI inspection and $47,438 for each MRS per helicopter.
Based on these figures, we estimate the total cost impact of the proposed
AD on U.S. operators to be $2,859,840, assuming, after an NDI, one MRS
would be replaced on each helicopter in the fleet because of the revised
life, cracks, or oversized dowel pin bores and the recordkeeping cost
would be negligible.
REGULATORY FINDINGS
We have determined that this proposed AD would not have federalism
implications under Executive Order 13132. Additionally, 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 that the 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.
We prepared a draft economic evaluation of the estimated costs to comply
with this proposed AD. See the AD docket to examine the draft economic
evaluation.
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.
LIST OF SUBJECTS IN 14 CFR PART 39
Air transportation, Aircraft, Aviation safety, Safety.
THE PROPOSED AMENDMENT
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend part
39 of the Federal Aviation Regulations (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. Section 39.13 is amended by removing Amendment 39-10943 (63 FR 69177,
December 16, 1998), and by adding a new airworthiness directive (AD),
to read as follows: