Turbine Wheels By P/N

Effective Date - 01/13/1988
Recurring - No
Supersedes - N/A
Superseded by - N/A
Amendment 39-5781.
Applies to Garrett Model GTCP 85 series Auxiliary Power Units equipped with one-piece cast turbine wheels, Part Nos. 968095-X, 3604604-X, 3606982-1, and 3842072-1.

Compliance required as indicated, unless previously accomplished. To prevent turbine wheel separation and resulting containment shroud fragmentation, accomplish the following:
A. Install the augmentation containment ring, part number 3612249-1, in Garrett Model GTCP 85 series auxiliary power units in accordance with the accomplishment instructions of Garrett Service Bulletin GTCP 85-49-5689, dated July 24, 1987, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region, as follows:
1. On in-flight operable units, within 18 months after the effective date of this AD.
2. On ground-operable-only units, within 36 months after the effective date of this AD.

B. Installation of the Hastelloy S turbine shroud, in accordance with Garrett Service Bulletin 85-49-5700, dated July 20, 1987, or later FAA approved revisions, is considered an acceptable alternate means of compliance with this AD.

C. An alternate means of compliance with this AD which provides an acceptable level of safety may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a base to comply with the requirements of this AD. All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Garrett Aviation Services Company, Data Distribution, Department H64-5, P.O. Box 29003, Phoenix, Arizona 85038. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or at 4344 Donald Douglas Drive, Long Beach, California. This amendment becomes effective January 13, 1988.