97-19-10: Main Transmission Plates Inspection

97-19-10 ERICKSON AIR-CRANE CO.: Amendment 39-10130. Docket No. 96-SW-04-AD. Supersedes AD 77-20-01, Amendment 39-3045 and Amendment 39-3064. Applicability: Sikorsky Aircraft-manufactured Model S-64E helicopters, with main gearbox assembly second stage lower planetary plate (plate), part number (P/N) 6435-20229-102, reidentified as P/N 6435-20229-102-TS-107 after rework, or P/N 6435-20229-104, 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 prevent failure of the plate due to fatigue cracking, which could lead to failure of the main gearbox and subsequent loss of control of the helicopter, accomplish the following: (a) For plate, part number (P/N) 6435-20229-102 and P/N 6435-20229-102-TS-107, at 1,300 hours total time-in-service (TIS), inspect and rework or replace the plate, as appropriate, in accordance with the Accomplishment Instructions, paragraph 2A., steps (1), and (3) through (11), of Erickson Air Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995. (b) For any plate, P/N 6435-20229-102, that has been reworked and identified with "TS- 107", and for plate, P/N 6435-20229-104, at 1,500 hours TIS and thereafter at intervals not to exceed 70 hours TIS, inspect the plate in accordance with the Accomplishment Instructions, paragraph 2B., step (1), of Erickson Air-Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995. If a crack is found, replace the main gearbox assembly with an airworthy assembly. (c) This AD revises the airworthiness limitation section of the maintenance manual by establishing a retirement life of 2,600 hours TIS for the main gearbox assembly second stage planetary plate, P/N 6435-20229-102, reidentified as P/N 6435-20229-102-TS-107 after rework, and P/N 6435-20229-104. (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, Rotorcraft Certification Office, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office. NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Certification Office. (e) 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. (f) The inspections and rework or replacement, as necessary, shall be done in accordance with Erickson Air Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995. 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 Erickson Air-Crane Co., 3100 Willow Springs Rd., P.O. Box 3247, Central Point, OR 97502. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, 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. (g) This amendment becomes effective on October 17, 1997.