[Federal Register Volume 66, Number 71 (Thursday, April 12, 2001)]
[Proposed Rules]
[Pages 18886-18888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9074]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-SW-43-AD]
RIN 2120-AA64


Airworthiness Directives; Sikorsky Aircraft Corporation Model S-
61A, D, E, L, N, NM, R, and V Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes superseding an existing airworthiness 
directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-
61A, D, E, L, N, NM, R, and V helicopters. That AD currently requires a 
nondestructive inspection (NDI) for a crack in the main rotor shaft 
(shaft) and replacing any cracked shaft. This action would require 
establishing and defining new life limits and removing certain shafts 
from service. This proposal is prompted by the final results of fatigue 
tests indicating the need to establish life limits for certain shafts. 
The actions specified by the proposed AD are intended to prevent 
structural failure of the shaft, loss of power to the main rotor, and 
subsequent loss of control of the helicopter.

DATES: Comments must be received on or before June 11, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2000-SW-43-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at [email protected]. Comments may be 
inspected at the Office of the Regional Counsel between 9 a.m. and 3 
p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Wayne Gaulzetti, Aviation Safety 
Engineer, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, MA 01803, telephone (781) 238-7156, fax 
(781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments will 
be considered before taking action on the proposed rule. The proposals 
contained in this document may be changed in light of the comments 
received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available in the Rules Docket for 
examination by interested persons. A report summarizing each FAA-public 
contact concerned with the substance of this proposal will be filed in 
the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their mailed 
comments submitted in response to this proposal must submit a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. 2000-SW-43-AD.'' The postcard will be date 
stamped and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2000-SW-43-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137.

Discussion

    On December 7, 1998, the FAA issued AD 98-26-02, Amendment 39-10943 
(63 FR 69177, December 16, 1998), for Sikorsky Model S-61A, D, E, L, N, 
NM, R, and V helicopters. That AD required an NDI of certain shafts 
used in repetitive external lift (REL) operations, replacing any 
cracked shaft, appropriately marking shafts, and establishing a new 
shaft retirement life. That action was prompted by reports of cracked 
shafts in helicopters utilized in REL operations. The requirements of 
that AD are intended to detect a fatigue crack in the shaft that could 
result in shaft structural failure, loss of power to the main rotor, 
and subsequent loss of control of the helicopter.
    REL operation is defined as an operation during which the average 
number of external lifts equals or exceeds six per flight hour for any 
250-hour TIS period during the main gearbox overhaul interval. An 
external lift 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.
    Since the issuance of that AD, Sikorsky has issued an Alert Service 
Bulletin No. 61B35-68B, Revision B, dated July 6, 2000 (ASB), to 
establish a retirement time for shafts used in REL and non-REL 
operations and to perform an NDI on certain shafts with expired time. 
Sikorsky conducted fatigue testing, evaluated three S-61 shafts, and 
investigated two shafts that cracked in service. With this additional 
data and analysis, new life limits for shafts operated in all 
categories, REL and non-REL, and all configurations have been 
established.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Sikorsky Model S-61A, D, E, L, N, NM, R, and 
V helicopters of these same type designs, the proposed AD would 
supersede AD 98-26-02 to require for each shaft, part number (P/N) 
S6135-20640-001, S6135-20640-002, or S6137-23040-001, the following:
     Determine whether the shaft has been utilized in REL or 
non-REL operations;
     If the shaft has been used in REL operations, perform an 
NDI.
     Acid-etch the letters ``REL'' on any airworthy shaft that 
will be used in REL operations;
     Remove from service at or before the next main gearbox 
overhaul, any

[[Page 18887]]

shaft using an oversize dowel pin bore repair identified as TS-281 or 
TS-041-3; and
     This proposal would also establish new life limits for 
shafts in all REL and non-REL operations.
    The FAA estimates that 30 helicopters of U.S. registry involved in 
REL and 30 involved in non-REL operations would be affected by this 
proposed AD. It would take approximately 2.2 work hours to inspect a 
shaft when it is removed during transmission overhaul, and the average 
labor rate is $60 per work hour. Required material for each shaft 
inspection would cost approximately $50 per shaft, and a replacement 
shaft costs $44,753. Based on these figures, the total cost impact of 
the proposed AD on U.S. operators is estimated to be $1,353,510, 
assuming that all shafts used in REL operation would need to be 
replaced as a result of this proposal.
    The regulations proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

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, 
to read as follows:

Sikorsky Aircraft Corporation: Docket No. 2000-SW-43-AD. Supersedes 
AD 98-26-02, Amendment 39-10943, Docket No. 96-SW-29-AD.

    Applicability: Model S-61A, D, E, L, N, NM, R, and V 
helicopters, with main rotor shaft (shaft), part number (P/N) S6135-
20640-001, S6135-20640-002, or S6137-23040-001, installed, 
certificated in any category.

    Note 1: This AD applies to each helicopter identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (g) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect a fatigue crack in the shaft that could result in 
shaft structural failure, loss of power to the main rotor, and 
subsequent loss of control of the helicopter, accomplish the 
following:
    (a) Within the next 30 days or 240 hours time-in-service (TIS), 
whichever occurs first, determine if the shaft has been used in 
repetitive external lift (REL) operations. REL operation is defined 
as an operation during which the average number of external lifts 
equals or exceeds 6 per flight hour for any 250-hour TIS period 
during the main gearbox overhaul interval. An external lift 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.
    (1) On the component log card or equivalent record, record the 
total number of hours TIS during which external lifts have been 
conducted and the number of external lifts conducted during each 
hour.
    (2) If the hours TIS of external lift operations or the number 
of lifts cannot be determined, assume REL operations were conducted.
    (b) Within the next 1,100 hours TIS, conduct a non-destructive 
inspection (NDI) for a crack on shafts used in REL operations in 
accordance with the Overhaul Manual.
    (1) Before further flight, replace any cracked shaft with an 
airworthy shaft.
    (2) If the shaft has been used or will be used in REL 
operations, prior to installation, mark the shafts in accordance 
with the Accomplishment Instructions in paragraphs 2E and 2F of 
Sikorsky Aircraft Corporation Alert Service Bulletin (ASB) No. 
61B35-68B, dated July 6, 2000. Once a shaft has been designated and 
marked as an REL shaft, it is life-limited in accordance with 
paragraph (g) of this AD for the remainder of that shaft's airworthy 
service life.
    (c) During or before the next main gearbox overhaul, remove all 
shafts used in REL or non-REL operations that were repaired using an 
oversize dowel pin bore repair TS-281 or TS-041-3, and replace the 
shaft with an airworthy shaft. Shafts repaired using TS-281 or TS-
041-3 cannot be reinstalled in any gearbox.
    (d) For shafts that have been used in REL operations,
    (1) On or before attaining 2,200 hours TIS, remove any shaft 
that has been modified (modified REL shaft) in accordance with 
Sikorsky Customer Service Notice 6135-10, dated March 18, 1987, and 
Sikorsky ASB No. 61B35-53, dated December 2, 1981.
    (2) On or before attaining 1,500 hours TIS, remove any shaft 
that has not been modified (unmodified REL shaft) in accordance with 
Sikorsky Customer Service Notice 6135-10, dated March 18, 1987, and 
Sikorsky ASB No. 61B35-53, dated December 2, 1981.
    (3) On or before attaining 535 hours TIS, remove any shaft, 
modified or unmodified, if the total TIS is unknown.
    (e) For shafts used exclusively in non-REL operations,
    (1) Record the hours TIS. If the total hours TIS cannot be 
determined, record 12,500 hours TIS.
    (2) On or before attaining 42,000 hours TIS, remove any shaft 
used exclusively in non-REL operations.
    (f) This AD revises the airworthiness limitations section of the 
maintenance manual by establishing for shafts, P/N S6135-20640-001, 
S6135-20640-002, and S6137-23040-001:
    (1) A retirement life for shafts that have been used in REL 
operations as follows: 1,500 hours TIS for unmodified shafts; 2,200 
hours TIS for modified shafts; or 535 hours TIS for modified or 
unmodified shafts when previous TIS is unknown; and
    (2) A retirement life for shafts used exclusively in non-REL 
operations of 42,000 hours TIS.
    (g) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Boston Aircraft Certification 
Office. Operators shall submit their requests through an FAA 
Principal Maintenance Inspector, who may concur or comment and then 
send it to the Manager, Boston Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Boston Aircraft Certification Office.

    (h) Special flight permits may be issued in accordance with 14 
CFR 21.197 and 21.199 to operate the helicopter to a location where 
the requirements of this AD can be accomplished.


[[Page 18888]]


    Issued in Fort Worth, Texas, on April 4, 2001.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 01-9074 Filed 4-11-01; 8:45 am]
BILLING CODE 4910-13-P