[Federal Register Volume 62, Number 181 (Thursday, September 18, 1997)]
[Proposed Rules]
[Pages 48961-48963]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-24795]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-29-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 the adoption of a new airworthiness 
directive (AD) that is applicable to Sikorsky Aircraft Corporation 
(Sikorsky) Model S-61 A, D, E, L, N, NM, R, and V helicopters. This 
proposal would require a nondestructive inspection (NDI) for cracks in 
the main rotor shaft (shaft), and require removal of any shaft with a 
crack and replacement with an airworthy shaft. This proposal would also 
require appropriate marking of shafts and log book entries by the 
operator to determine the shaft retirement life, and would establish a 
new retirement life for the shaft. This proposal is prompted by four 
reports of cracks occurring in helicopters that were utilized in 
repetitive external lift (REL) operations. The actions specified by the 
proposed 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

[[Page 48962]]

subsequent loss of control of the helicopter.

DATES: Comments must be received by November 17, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 96-SW-29-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137. Comments may be inspected at this location between 9:00 
a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial 
Tech Support, 6900 Main Street, P.O. Box 9729, Stratford, CT 06497-
9129. This information may be examined at the FAA, Office of the 
Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Frank Walsh, Aerospace Engineer, 
ANE-150, 12 New England Executive Park, Burlington, MA 01803, telephone 
(781) 238-7158, 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, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice 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, both before and after the closing 
date for comments, 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 comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 96-SW-29-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 Assistant Chief Counsel, Attention: Rules 
Docket No. 96-SW-29-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137.

Discussion

    This document proposes the adoption of a new AD that is applicable 
to Sikorsky Model S-61 A, D, E, L, N, NM, R, and V helicopters. This 
proposal would require a NDI of the shaft, part number (P/N) S6135-
20640-001, S6135-20640-002, or S6137-23040-001, used in REL operations 
within the next 1,000 hours time-in-service (TIS), or at the next main 
gearbox overhaul. The NDI would be required to be performed in 
accordance with Sikorsky Alert Service Bulletin (ASB) No. 61B35-68, 
dated July 19, 1996. This proposal would also establish retirement 
lives for certain shafts utilized in REL operations. Therefore, for 
shafts installed on helicopters utilized in REL operations that have 
not been modified in accordance with Sikorsky Customer Service Notice 
(CSN) 6135-10, dated March 18, 1987, and Sikorsky ASB No. 61B35-53, 
dated December 2, 1981, the retirement life would be 1,500 hours time-
in-service (TIS). For shafts installed on helicopters utilized in REL 
operations that have been modified in accordance with Sikorsky CSN 
6135-10, dated March 18, 1987, and Sikorsky ASB No. 61B35-53, dated 
December 2, 1981, the retirement life would be 2,000 hours TIS. This 
proposal is prompted by four reports of cracks occurring in helicopters 
that were utilized in REL operations. The actions specified by the 
proposed 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.
    The FAA has reviewed Sikorsky ASB No. 61B35-68, dated July 19, 
1996. That ASB describes procedures for determining the TIS during 
which the helicopter was utilized in REL operations; performing a NDI 
of the shaft; marking the shafts that have no crack; and acid-etching 
the letters ``REL'' on airworthy shafts prior to their installation on 
a helicopter that will be used in REL operations. The ASB also 
establishes new life limits for the shaft.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Sikorsky Model S-61 A, D, E, L, N, NM, R, and 
V helicopters of the same type design, the proposed AD would require 
determining and recording on the component log or equivalent record the 
number of hours TIS during which the helicopter was utilized in REL 
operations, as well as the number of external lifts conducted during 
each hour TIS in which external lifts were conducted; performing a NDI 
of the shaft; marking the shafts that have no crack; and acid-etching 
the letters ``REL'' on airworthy shafts prior to their installation on 
a helicopter that will be used in REL operations. The proposed AD would 
also establish a new retirement life for the shaft. The actions would 
be required to be accomplished in accordance with the service bulletins 
described previously.
    The FAA estimates that 30 helicopters of U.S. registry that are 
involved in REL operations would be affected by this proposed AD, that 
it would take approximately 2.2 work hours per helicopter to accomplish 
the proposed actions during the next scheduled overhaul, and that the 
average labor rate is $60 per work hour. Required parts for the 
inspection would cost approximately $50 per helicopter. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $5,460, assuming that no shafts will need to be 
replaced as a result of this AD.
    The regulations proposed herein would not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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.

[[Page 48963]]

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 adding a new airworthiness directive 
to read as follows:

Sikorsky Aircraft Corporation: Docket No. 96-SW-29-AD.

    Applicability: Model S-61 A, 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 
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 use the authority 
provided in paragraph (d) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    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 calendar days or 240 hours time-in-
service (TIS) after the effective date of this AD, whichever occurs 
first, determine if the shaft has been used in repetitive external 
lift (REL) operations. REL operation is defined as 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. Record the total number 
of hours TIS during which external lifts have been conducted, as 
well as the number of external lifts conducted during each hour, on 
the component log card or equivalent record. If the number of 
external lifts cannot be determined, assume 6 external lifts were 
conducted during each hour TIS in which external lifts were 
conducted. If the hours TIS of external lift operations cannot be 
determined, assume REL operations were conducted.
    (b) For shafts used in REL operations, within the next 1,000 
hours TIS after the effective date of this AD, conduct a non-
destructive inspection (NDI) for cracks in the shaft in accordance 
with the Overhaul Manual. If a crack is discovered in a shaft, 
remove the shaft and replace it with an airworthy shaft. Mark the 
removed airworthy shafts and the replacement shafts in accordance 
with the Accomplishment Instructions in paragraphs 2E and 2F of 
Sikorsky Aircraft Corporation ASB No. 61B35-68, dated July 19, 1996. 
Once a shaft has been designated and marked as an REL shaft, it is 
life-limited accordingly for the remainder of that shaft's airworthy 
service life.
    (c) Retire all shafts that have been used in REL operations as 
follows:
    (1) Shafts that have been modified in accordance with Sikorsky 
Customer Service Notice 6135-10, dated March 18, 1987, and Sikorsky 
ASB No. 61B35-53, dated December 2, 1981 (modified REL shafts), must 
be removed from service on or before attaining 2,000 hours TIS.
    (2) Shafts that have not been modified in accordance with 
Sikorsky Customer Service Notice 6135-10, dated March 18, 1987, and 
Sikorsky ASB No. 61B35-53, dated December 2, 1981 (unmodified REL 
shafts), must be removed from service on or before attaining 1,500 
hours TIS.
    (d) 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.

    (e) This AD revises the Limitations section of the maintenance 
manual by establishing new retirement lives of 1,500 hours TIS for 
unmodified REL shafts and 2,000 hours TIS for modified REL shafts.
    (f) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the helicopter to a location where 
the requirements of this AD can be accomplished.

    Issued in Fort Worth, Texas, on September 12, 1997.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 97-24795 Filed 9-17-97; 8:45 am]
BILLING CODE 4910-13-U