AD 86-16-03

86-16-03 ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. (ALLISON, formerly DETROIT DIESEL ALLISON): Amendment 39-5366. Applies to Allison Model 250-C28B and -C28C engines installed in aircraft certificated in any category. The following engine models and turbine serial numbers are affected:

ENGINE MODEL ENGINE SERIAL NUMBER TURBINE SERIAL NUMBER 250-C28B CAE 860011 thru 860787 CAT 70011 thru 70804 250-C28C CAE 280001 thru 280097 CAT 28001 thru 28098

EXCEPT: Existing Model 250-C28B and -C28C engines which have incorporated Allison Commercial Engine Alert Bulletin CEB-A-72-2138 dated May 15, 1986, or FAA approved equivalent. Compliance is required as indicated unless already accomplished. To prevent possible internal oil fires that can cause cracks under the rim of the first stage turbine wheel which can progress to an on-speed failure/uncontained failure, accomplish the following: (a) Maintain a record of oil consumed and flight hours, beginningon the effective date of this AD, until compliance with Paragraph (c). (b) Troubleshoot and repair, before further flight, any engine that exhibits any of the following conditions: (1) High oil consumption (1 quart in 5 hours, .05 gallons per hour, or .19 liters per hour) or significant step change of 100 percent or greater in oil consumption. (2) Excessive smoking on deceleration and/or shutdown with or without associated high oil consumption or significant increase in oil consumption. NOTES: (1) The checks required by Paragraph (a), (b)(1), and (b)(2) of this AD may be performed by the pilot and must be recorded in accordance with FAR 43.9. (2) Allison Model 250-C28 Series Operations and Maintenance/Overhaul Manual addresses troubleshooting and repairs. (c) Install Number 8 Bearing Scavenge Line Air/Oil Centrifugal Separator Assembly, P/N 23034772, in accordance with Allison Commercial Engine Alert Bulletin CEB-A-72-2138 dated May 15, 1986, or FAA approved equivalent, not later than January 31, 1987. NOTE: Installation of the Number 8 Bearing Scavenge Line Air/Oil Centrifugal Separator Assembly, P/N 23034772, does not relieve the operator of proper monitoring of oil consumption, changes in oil consumption or smoking during operation as described in the Model 250-C28 Series Engine Operations and Maintenance Manual. Aircraft may be ferried in accordance with the provisions of FAR 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, FAA, 2300 East Devon Avenue, Des Plaines, Illinois 60018. 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 CEB-A-72-2138 dated May 15, 1986, 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, IN 46206- 0420. This document also may be examined at the Office of Regional Counsel, FAA, ATTN: Rules Docket No. 86-ANE-28, 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 August 13, 1986.