AD 97-24795

[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]

======================================================================= -----------------------------------------------------------------------

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).

-----------------------------------------------------------------------

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