AD 94-14-20 Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A Helicopters

Models named: S-76A. Read the applicability below — it usually turns on serial or part numbers too.

Model S-76A helicopters, with tail rotor blade (blade) assembly, part number (P/N) 76101-05001 (all dash numbers) or 76101-05101 (all dash numbers), installed with more than 130 hours time-in-service (TIS), 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 (c) 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.

Required within 25 hours TIS, unless accomplished previously. To prevent the blade spar elliptical centering plug (centering plug) from disbonding and moving out of position, loss of tail rotor control, and subsequent loss of control of the helicopter, accomplish the following: (a) Inspect the centering plug for disbonding of the polyurethane filler that fills the space between the aluminum centering plug and the graphite spar in accordance with the Accomplishment Instructions, paragraph 3.A.(1) and (2), of Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-65-35B (153B), Revision B, dated October 2, 1997 (ASB). Note 2: The 500-hours TIS repetitive inspections contained in the Accomplishment Instructions, paragraph 3.D., of Sikorsky Aircraft Corporation Alert Service Bulletin 76-65-35A, Revision A, dated February 29, 1984, are not required by this AD. (1) If the inspection of the centering plug reveals disbonding of 1/2 -inch or less in length, install a retaining pad, P/N 76102-05004-111, in accordance with the Accomplishment Instructions, paragraph 3.C., of the ASB. (2) For disbonds greater than 1/2 -inch in length, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(1), of the ASB except you are not required to contact Sikorsky Worldwide Customer Service. If blades are found with polyurethane filler excessively cracked or deteriorated to extent of breaking away from the spar or aluminum plug by 0.005-inch or greater, replace the blade with an airworthy blade. (3) For spars with complete spar to centering plug disbond in which the polyurethane filler is intact and remains fully bonded to the centering plug, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(2), of the ASB. (4) For spars with complete polyurethane filler to centering plug disbond in which the polyurethane filler is intact and remains fully bonded to the spar, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(3) of the ASB. (b) Install a retaining pad, P/N 76102-05004-111, in accordance with the Accomplishment Instructions, paragraph 3.C., of the ASB. (c) 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, FAA. 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Boston Aircraft Certification Office. (d) 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 if a retaining pad has been installed. (e) The inspections, modifications, and repair shall be done in accordance with the Accomplishment Instructions, paragraphs 3.A.(1), 3.A.(2), 3.B.(1), 3.B.(2), 3.B.(3), and 3.C., of Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-65-35B (153B), Revision B, dated October 2, 1997. This incorporation by reference was approved by the Director of the Federal Register 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 Tech Support, 6900 Main Street, Stratford, Connecticut 06614, phone (203) 386-3001, fax (203) 386-5983. 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 Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (f) This amendment becomes effective on June 8, 2001. Issued in Fort Worth, Texas, on April 20, 2001. Larry M. Kelly, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 01-10730 Filed 5-3-01; 8:45 am] BILLING CODE 4910-13-U