AD 97-10-15 Airworthiness Directives; Sikorsky Aircraft-Manufactured Model S- 64F Helicopters

Models named: S-64F. Read the applicability below — it usually turns on serial or part numbers too.

Sikorsky Aircraft-manufactured Model S-64F helicopters, with main gearbox second stage lower planetary plate, part number (P/N) 6435-20516-101, 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 (c) 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.

Required as indicated, unless accomplished previously. To prevent failure of the main gearbox second stage lower planetary plate (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 main gearbox assemblies containing plate, P/N 6435- 20516-101, with 2,000 hours time-in-service (TIS) or more: (1) Prior to the first flight of each day, inspect the main oil filter for magnesium contamination. If magnesium contamination is discovered, replace the main gearbox assembly. (2) Within the next 100 hours TIS after the effective date of this AD, and thereafter at intervals not to exceed 500 hours TIS, inspect, and, if necessary, replace the main gearbox assembly in accordance with the Accomplishment Instructions of Section 2, Paragraph B, of Erickson Service Bulletin No. 64F35-2A dated November 8, 1995. (b) At the next overhaul of the main gearbox assembly, inspect and rework the plate, P/N 6435-20516-101, in accordance with Section 2, Paragraphs C(1) and (3) through (11) of Erickson Service Bulletin No. 64F35-2A, dated November 8, 1995. (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, 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. (d) 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. (e) The inspection and rework shall be done in accordance with Erickson Air-Crane Co. Service Bulletin No. 64F35-2A, 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, Oregon 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. (f) This amendment becomes effective on June 27, 1997. Issued in Fort Worth, Texas, on May 9, 1997. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 97-12855 Filed 5-22-97; 8:45 am] BILLING CODE 4910-13-U