Turbine Wheels By P/N

Effective Date - 05/26/1993
Recurring - No
Supersedes - N/A
Superseded by - 97-04-04
GARRETT
Amendment 39-8545.
Docket 92-NM-174-AD.

Applicability: Garrett Model GTCP85 series auxiliary power units (APU), equipped with one-piece cast turbine wheels, part numbers 968095-X, 3604604-X 3606982-1, or 3842072-1,-2,-3; as installed in, but not limited to, British Aerospace Model BAC 1-11 series airplanes, Boeing Model 707 series airplanes, Boeing Model 727 series airplanes, Boeing Model 737 series airplanes, Lockheed Model L382 series airplanes, McDonnell Douglas Model DC-8-70 series airplanes, McDonnell Douglas Model DC-9 series airplanes, and McDonnell Douglas Model MD-88 airplanes; certificated in any category.

Compliance: Required as indicated, unless accomplished previously. To prevent turbine shroud fragments from exiting the APU and puncturing the APU compartment, which could lead to reduced fire protection capability of the APU compartment, accomplish the following:
(a) For in-flight operable Garrett Model GTCP85 series Auxiliary Power Units (APU): Within 24 months after the effective date of this AD, accomplish the requirements of either paragraph (a)(1) or (a)(2) of this AD.
(1) Remove the turbine wheel shrouds constructed of Inconel 718 material and install a shroud constructed of Hastelloy "S" material, part number 3611904-1, in accordance with Garrett Service Bulletin GTCP85-49-5700, dated July 20, 1987; Revision 1, dated October 6, 1988; or Revision 2, dated August 31, 1989.
(2) Install turbine shroud containment augmentation ring, part number 3616426-1, in accordance with Garrett Alert Service Bulletin GTCP85-49-A6706, dated December 7, 1992.
(b) For on-ground-only operable Garrett Model GTCP85 series APU's: Within 36 months after the effective date of this AD, accomplish the requirements of either paragraph (b)(1) or (b)(2) of this AD.
(1) Remove the turbine wheel shroud constructed of Inconel 718 material and install a shroud constructed of Hastelloy "S" material, part number 3611904-1, in accordance with Garrett Service Bulletin GTCP85-49-5700, dated July 20, 1987; Revision 1, dated October 6, 1988; or Revision 2, dated August 31, 1989.
(2) Install turbine shroud containment augmentation ring, part number 3616426-1, in accordance with Garrett Alert Service Bulletin GTCP85-49-A6706, dated December 7, 1992.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO. NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. (d) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) The removal and installations shall be done in accordance with the following Garrett service bulletins, which contain the specified effective pages: Service Bulletin Revision Level Date Referenced and Date Page Number Shown on Page Shown on Page GTCP85-49-5700 1-10 Original July 20, 1987 Original July 20, 1987 GTCP85-49-5700 1-4, 7-10 1 October 6, 1988 Revision 1 October 6, 1988 5-6 Original July 20, 1987 GTCP85-5700 1, 5-10 2 August 31, 1989 Revision 2 August 31, 1989 2-4 1 October 6, 1988 GTCP85-49-A6706 1-10 Original December 7, 1992 Original December 7, 1992 This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552 (a) and 1 CFR Part 51. Copies may be obtained from Garrett Airlines Services Division, Technical Publications, Department 65-70, P.O. Box 52170, Phoenix, Arizona 85072-2170. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on May 26, 1993. FOR FURTHER INFORMATION CONTACT: Mr. Robert Baitoo, Aerospace Engineer, Los Angeles Aircraft Certification Office, Propulsion Branch, ANM-140L, FAA, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, California 90806-2425; telephone (310) 988-5245; fax (310) 988-5210.