Airworthiness Directive · Amendment 39-15062 · Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters
Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters
Model S-76A, B and C helicopters with a main rotor shaft assembly (M/R shaft) listed in the following table installed, certificated in any category.
| M/R shaft part No. | Serial No. |
|---|---|
| 76351-09030-all dash numbers | B015-00782 through B015-00791; B015-00811 through B015-00816; E015-00844 through E015-00865; and E015-00908 through E015-00918. |
| 76351-09630-041 | C213-00436 through C213-00454; D213-00537 through D213-00545; and D213-00575 through D213-00585. |
This amendment adopts a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, B, and C helicopters. This action requires a one-time ultrasonic inspection of the main rotor shaft assembly (M/R shaft) for cracking. This amendment is prompted by the discovery of cracking that occurred during the manufacturing of certain M/R shafts. The actions specified in this AD are intended to detect cracking in the M/R shaft, which could result in separation of the main rotor and subsequent loss of control of the helicopter.
To detect cracking in the M/R shaft, which could result in separation of the main rotor and subsequent loss of control of the helicopter, accomplish the following:
(a) Perform a one-time ultrasonic inspection of the M/R shaft for cracking in accordance with Nondestructive Testing/Inspection Technique, Ultrasonic Technique (UT) Number 5043, latest version. The ultrasonic inspection of the M/R shaft must be performed by a Level II or Level III inspector, qualified under the guidelines established by MIL-STD-410E, ATA Specification 105, AIA-NAS-410, or an FAA-accepted equivalent for qualification standards of Nondestructive Testing inspection/evaluation personnel. Recurrent training and examinations are part of the qualification requirements.
(1) For Model S-76A, B and C helicopters with a M/R shaft, P/N 76351-09630-041, installed, remove and inspect the M/R shaft in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(a) through 3.B.(1)(d) 5 of Sikorsky Alert Service Bulletin (ASB) No. 76-66-45A, Revision A, dated February 7, 2007.
(2) For Model S-76A helicopters with a M/R shaft, P/N 76351-09030—all dash numbers, installed, remove and inspect the M/R shaft in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(a) through 3.B.(1)(d) 5 of Sikorsky ASB No. 76-66-46, dated February 7, 2007.
(3) If a crack is found, replace the M/R shaft with an airworthy M/R shaft that has been ultrasonically inspected in accordance with paragraph (a) of this AD before further flight.
(4) Reassemble the lower bearing housing assembly, install the main gear box, and perform the ground run leak test in accordance with the Accomplishment Instructions, paragraphs 3.B.(1)(f) through 3.B.(1)(l) of either ASB No. 76-66-45A, Revision A or ASB No. 76-66-46, both dated February 7, 2007, as appropriate for your part-numbered M/R shaft.
(b) Before installing an affected M/R shaft, ultrasonically inspect the M/R shaft and reassemble the lower bearing housing assembly, install the main gear box, and perform the ground run leak test in accordance with the requirements of paragraph (a) of this AD.
(c) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Boston Aircraft Certification Office, FAA, ATTN: Kirk Gustafson, Aviation Safety Engineer, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7190, fax (781) 238-7170, for information about previously approved alternative methods of compliance.
(d) The ultrasonic inspection shall be done in accordance with the specified portions of Sikorsky Alert Service Bulletin (ASB) No. 76-66-45A, Revision A, and Sikorsky ASB No. 76-66-46, both dated February 7, 2007. The Director of the Federal Register approved this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main Street, Stratford, Connecticut, phone (203) 383-4866, e-mail address tsslibrary@sikorsky.com. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
