AD 86-03-01

86-03-01 GARRETT TURBINE ENGINE COMPANY (formerly the AiResearch Manufacturing Company of Arizona: Amendment 39-5212. Applies to all Model TFE731-2, -3, -3A, -3AR, -3B, -3BR, and - 3R turbofan engines installed in aircraft certified in all categories equipped with turbine interstage transition ducts, part numbers 3071486-3 through -10, 3072318-1 and -3, 3072726-1 and -2, identified by individual serial numbers (hereinafter referred to as duct(s)).

Compliance is required prior to the accumulation of 1,150 hours time in service from the effective date of this AD, unless already accomplished.

NOTE: A substantial number of additional ducts were found to be subject to the same defect after Garrett issued SB TFE731-72-3309, dated March 7, 1985. This SB was specified in the NPRM (50 FR 19033). Revision 1 of said SB, dated September 6, 1985, was subsequently issued, and it now contains complete listings of affected ducts. Therefore, engines which were determined to be unaffected in accordance with the original SB, must be reverified.

To prevent separation of the engine rear mount from the duct, accomplish the following:

(a) Determine, by engine visual inspection, whether the turbine interstage transition duct S/N is included in Table 1 or Table 2 of Garrett SB TFE731-72-3309, Revision 1, dated September 6, 1985, (SB 3309) or FAA- approved equivalent.

(1) Engine visual inspection which ensures that the duct S/N is not in Table 1 or Table 2 constitutes terminating action for this AD.

(2) Ducts listed in Table 1 are known to have inadequate weld penetration, and require modification or replacement as specified below. Ducts listed in Table 2 might have inadequate weld penetration, and must either pass the additional X-ray inspection or be modified or replaced, as specified below.

(b) Replace any duct listed in Table 1 of SB 3309 with a serviceable duct, or perform the actions of SB 3309, paragraph 2.B. (modification).

(c) Replace any duct listed in Table 2 of SB 3309 with a serviceable duct, or perform the actions of SB 3309, paragraph 2.C. (X-ray inspection and/or modification).

NOTES: (1) Regardless of statements in SB 3309 referring to the installation of the aft mount auxiliary bracket (in accordance with SB TFE731-72-3170) as an "interim compliance", such installation constitutes terminating action for this AD. Ducts which are modified by incorporation of the aft mount auxiliary bracket, shall not have the bracket removed and be returned to service unless the other actions of SB 3309, paragraph 2.B. or 2.C., as applicable, are performed.

(2) The aft mount auxiliary bracket requires a longer engine mount bolt which is a new aircraft part. Therefore, each type aircraft using this bracket must have an FAA-approved SB to complete the installation; otherwise the bracket shall not be used.

(d) For ducts which are determined to have a satisfactory weld at a clevis position used to mount the engine to the aircraft, but are determined to have an unsatisfactory weld(s) at the other clevis position(s), an FAA- approved alternative means of compliance with the provisions of SB 3309, paragraph 2.B.(2) or 2.C.(6), as applicable, is as follows:

(1) Cut through the bolt holes of the unsatisfactory clevis(es) in accordance with paragraph 2.F.(1) of SB TFE731-72-3159, Revision 5, dated September 6, 1985, or FAA-approved equivalent;

(2) Efface existing part number on duct and electrochemically etch new part number (0.0004 inch maximum depth) in accordance with:

OLD PART NO. NEW PART NO. 3071486-3 3071486-11 3071486-4 3071486-12 3071486-5 3071486-13 3071486-6 3071486-14 3071486-7 3071486-15 3071486-8 3071486-16 3071486-9 3071486-17 3071486-10 3071486-18 3072318-1 3076070-1 3072318-3 3076070-2 3072726-1 3076070-3 3072726-2 3076070-4

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, Western Aircraft Certification Office, P.O. Box 92007, Worldway Postal Center, Los Angeles, California 90009.

Upon submission of substantiating data by an owner or operator through an FAA maintenance inspector, the Manager, Western Aircraft Certification Office, P.O. Box 92007, Worldway Postal Center, Los Angeles, California 90009 may adjust the compliance time specified in this AD.

Garrett SB Nos. TFE731-72-3309, Revision 1, dated September 6, 1985; TFE731-72-3159, Revision 5, dated September 6, 1985; and TFE731-72-3170, Revision 2, dated March 7, 1985, 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 Garrett General Aviation Service Company, Department H65-1, Building 601AD, P.O. Box 29003, Phoenix, Arizona 85038.

These documents also may be examined at the Office of the Regional Counsel, Federal Aviation Administration, New England Region, Room 311, 12 New England Executive Park, Burlington, Massachusetts 01803.

This amendment becomes effective on February 24, 1986.