AD 81-13-12 R1

81-13-12 R1 DETROIT DIESEL ALLISON: Amendment 39-4179 as amended by Amendment 39-4701. Applies to all Model 250-C30, -C30P, and C30S engines and turbine assemblies equipped with 4th stage turbine nozzle assembly P/N 6898694 installed in aircraft certificated in all categories, EXCEPT:

1. Models 250-C30, -C30S: ENGINE SERIAL NO. TURBINE SERIAL NO. CAE 890690, 890691, CAT 95105, 95106, 890692, 890696, and subsequent 95108, 95109, and subsequent

2. Model 250-C30P: ENGINE SERIAL NO. TURBINE SERIAL NO. CAE 895086, 895087, and subsequent CAT 95110, 95111, 95112, and subsequent

Compliance is required as indicated unless already accomplished. To prevent cracks in P/N 6898694 4th stage turbine wheel nozzles leading to uncontained turbine wheel failures accomplish the following: a. Inspect, reduce life limits where applicable based on inspection results, and remove from service affected P/N 6898694 nozzles in compliance with the schedule, instructions, and inspection criteria provided in Detroit Diesel Allison Commercial Engine Alert Bulletin CEB-A-72-3056, Revision 3 dated March 30, 1983, or later FAA approved revisions. b. Special flight permits may be issued in accordance with FAR's 21.197 and 21.199 to operate aircraft to a base where compliance with this AD can be accomplished. c. Upon request of the operator, 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. 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 Detroit Diesel Allison, Division of General Motors Corporation, Indianapolis, Indiana 46206. These documents also maybe examined at the Office of Regional Counsel, FAA, 12 New England Executive Park, Burlington, Massachusetts 01803 weekdays, except federal holidays, between 8:00 a.m. and 4:30 p.m. Amendment 39-4179 became effective August 10, 1981. This Amendment 39-4701 becomes effective September 26, 1983.