AD 85-06-51

85-06-51 ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. (ALLISON, formerly DETROIT DIESEL ALLISON): Amendment 39-5050. Applies to Allison Model 250-C30 and -C30S engines, which incorporate P/N 23001915 magnetic plugs in the power and accessory gearbox cover and housing assembly, installed in Sikorsky S-76A helicopters certificated in any category. Within the next 50 hours time in service after the effective date of this AD, but not later than May 15, 1985, perform the following: Replace the two P/N 23001915 magnetic plugs installed in the power and accessory gearbox cover and housing assembly with two P/N 6871534 magnetic plugs, which do not provide for automatic burnoff of accumulated metal fuzz, in accordance with Allison Commercial Engine Alert Bulletin 250-C30, -C30S CEB-A- 72-3098, Revision 1 dated January 15, 1985, or FAA approved equivalent. Aircraft may be ferried in accordance with the provisions of Federal Aviation Regulations (FARs) Sections 21.197 and 21.199 to a base where the AD can be accomplished. Upon request, an equivalent means of compliance with the requirements of this AD may be approved by the Manager, Chicago Aircraft Certification Office, Federal Aviation Administration, 2300 East Devon Avenue, Des Plaines, Illinois 60018. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Allison Gas Turbine Division, General Motors Corp., P.O. Box 420, Indianapolis, IN 46206-0420. These documents also may be examined at the Office of Regional Counsel, FAA, ATTN: Rules Docket No. 85-ANE-14, 12 New England Executive Park, Burlington, Massachusetts 01803, weekdays, except Federal holidays, between 8:00 a.m. and 4:30 p.m. This amendment becomes effective May 10, 1985, to all those persons except those persons to whom it was made immediately effective by telegraphic AD T85-06-51, issued March 29, 1985, which contained this amendment.