85-25-07 R1 ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. (ALLISON, formerly DETROIT DIESEL ALLISON): Amendment 39-5188 as Amended by Amendment 39-5368. Applies to Allison Model 250-C28 and -C30 Series engines which incorporate outer combustion case assembly P/N 6899237 or 23009569, installed in aircraft certificated in any category.
Compliance is required as indicated unless already accomplished.
To prevent possible cracks at the butt or seam weld on outer combustion case P/Ns 6899237 and 23009569 from progressing to a point where the case could rupture and cause an inflight sudden loss of power/shutdown, accomplish the following:
(a) Model 250-C28B, -C28C, -C30, -C30P, -C30R, and -C30S engines
Inspect outer combustion assembly P/N 6899237 or 23009569 in accordance with the following:
(1) Prior to next flight, and at daily intervals thereafter, until compliance with Paragraphs (b) or (c), as appropriate, is accomplished, using a bright light (flashlight or equivalent) and mirror, inspect all of the outer combustion case welds which are located as follows:
(i) Horizontal butt welds on outer surface and between the air discharge tube attachment flanges and gas producer attachment flange on forward side.
(ii) Both forward and aft circumferential seam welds between outer case and inner liner.
(iii) Welds for attaching bosses for fuel nozzle, both combustion case drain valves, and both igniter plugs.
NOTES:
1. Pay particular attention to welds in areas defined in Sub-paragraphs (i) and where these horizontal welds meet the circumferential welds defined in Sub-paragraph (ii).
2. The above daily inspection may be performed by the pilot and must be recorded in accordance with FAR Section 43.9.
Detection of any crack(s) requires removal of the outer combustion case from service before further flight.
(2) Within the next five hours time-in-service, unless already accomplished within the last 20 hours time-in-service, andthereafter at intervals not to exceed 25 hours time-in-service from the last inspection, until compliance with Paragraphs (b) or (c), as appropriate, is accomplished, in addition to Paragraph (1) above, inspect the areas of horizontal butt weld between the air discharge tube attachment flanges and gas producer attachment flange on the forward side of the outer combustion case as follows:
(i) Apply dye penetrant, dye check, or other appropriate penetrant to the designated areas which will reveal crack(s), or
(ii) Apply a soap solution to the designated areas and, using a suitable power source to motor engine to at least 20 percent N1, look for bubbles to reveal if any crack(s) are present.
Detection of any crack(s) requires removal of the outer combustion case from service before further flight.
(b) Model 250-C30 and -C30S engines installed in Sikorsky Model S-76A rotorcraft
Within the next 150 hours time-in-service after the effective date of this AD, but not laterthan January 31, 1986, perform the following:
Replace/modify outer combustion case assembly P/Ns 6899237 and 23009569 with/to P/Ns 23030910 and 23030911, respectively, in accordance with Allison CEB-A-72-2113/3115, Revision 2, dated January 15, 1986, or prior issues, or FAA approved equivalent.
(c) Model 250-C28B, -C28C, -C30, -C30P, -C30R, and -C30S engines installed in other than Sikorsky S-76A rotorcraft
At the next turbine repair/overhaul event, but not later than June 30, 1986, perform the following:
Replace/modify outer combustion case assembly P/Ns 6899237 and 23009569 with/to P/Ns 23030910 and 23030911, respectively, in accordance with Allison CEB-A-72-2113/3115, Revision 2, dated January 15, 1986, or prior issues, or FAA approved equivalent.
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 CEB-A-72-2113/3115, Revision 2, dated January 15, 1986, 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 copies 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, FAA, ATTN: Rules Docket No. 85-ANE-43, 12 New England Executive Park, Burlington, Massachusetts 01803, weekdays, except Federal holidays, between 8:00 a.m. and 4:30 p.m.
This amendment amends Amendment 39-5188, 51 FR732, AD 85-25-07, effective January 6, 1986.
This Amendment 39-5368 becomes effective August 15, 1986, as to all persons except those persons to whom it was made immediately effective by priority letter AD 85-25-07 R1, issued January 22, 1986, which contained this amendment.