AD 88-07-06

88-07-06 ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORPORATION (Allison, formerly Detroit Diesel Allison): Amendment 39-5860. Applies to Allison Model 250-C30 Series engines installed in, but not limited to, Sikorsky Model S-76A, Bell Model 206L-3, Bell Model 206L-1, modified to incorporate the Allison 250-C30 engine, Aerospatiale Model AS-350D "ASTAR" modified to incorporate the Allison 250-30M engine, and McDonnell Douglas Helicopter Company (Hughes) Model 369F and 369FF aircraft. The following engine models and turbine serial numbers are affected:

ENGINE MODEL TURBINE SERIAL NUMBER 250-C30 CAT 90001 thru 90683, 95001 thru 95600 250-C30S CAT 90001 thru 90683, 95001 thru 95600 250-C30M CAT 95001 thru 95600 250-C30P CAT 95001 thru 95600, 97501 thru 97550 250-C30L CAT 95001 thru 95600, 97501 thru 97550 250-C30R(T703-AD-700) AT 19001 thru 19140

EXCEPT: Existing model 250-C30 series engines which have incorporated Part II or III of Allison CommercialEngine Alert Bulletin 250-C30, CEB-A-72-3165, dated August 31, 1987, or FAA approved equivalent. Compliance is required as indicated, unless already accomplished. To prevent possible cracks of the Gas Producer Support Pressure Oil Tube Assembly, P/N 6892825, or P/N 23037410, from progressing to where a loss of engine oil could cause an in-flight shutdown, accomplish the following: (a) Following the last flight of each day after the effective date of this AD, until compliance with paragraph (b) or (c) is accomplished, check for oil leaks and, if a leak is found remove before further flight the Gas Producer Support Pressure Oil Tube Assembly, P/N 23037410 or P/N 6892825, in accordance with Part I of Allison Commercial Engine Alert Bulletin 250-C30, CEB-A-72-3165, dated August 31, 1987, or FAA approved equivalent. NOTE: The checks required above may be performed by the pilot and must be recorded in accordance with FAR Section 43.9. (b) Replace Gas Producer Support Pressure Oil Tube Assembly P/N 23037410 with P/N 23038235 or an FAA approved equivalent in accordance with Part II of Allison Commercial Engine Alert Bulletin 250-C30, CEB-A-72-3165, dated August 31, 1987, not later than April 15, 1988. (c) Replace Gas Producer Support Pressure Oil Tube Assembly P/N 6892825 with number 8 Bearing Pressure Oil Fitting Assembly, P/N 23035275, and Tube Assembly, P/N 23038235, or FAA approved equivalents in accordance with Part III of Allison Commercial Engine Alert Bulletin 250-C30, CEB-A-72-3165, dated August 31, 1987, or FAA approved equivalent, not later than July 1, 1988. (d) Aircraft may be ferried in accordance with the provisions of Federal Aviation Regulations (FAR) 21.197 and 21.199 to a base where the AD can be accomplished. (e) 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. (f) Upon submission of substantiating data by an owner or operator through an FAA maintenance inspector, the Manager, Chicago Aircraft Certification Office may adjust the compliance time specified in this AD. Allison Commercial Engine Alert Bulletin 250-C30 CEB-A-72-3165 dated August 31, 1987, identified and described in this document, is 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 this document from the manufacturer may obtain a copy upon request to Allison Gas Turbine Division, General Motors Corp., P.O. Box 420, Indianapolis, Indiana 46206-0420. This document also may be examined at the office of Regional Counsel, Federal Aviation Administration, Attn: Rules Docket No. 87-ANE-26, 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 March 30, 1988.