AD 74-10-10

74-10-10 AIRESEARCH MANUFACTURING COMPANY OF ARIZONA: Amendment 39-1842 as amended by Amendment 39-1868 is further amended by Amendment 39-2253. Applies to Model TPE331-1-151B, -2-201C, -3U-307G, -5-251C, -5-251K and -6-251M engines.

Compliance required as indicated.

To detect, correct and prevent loosening of the fuel control assembly mounting and support bracket fasteners, accomplish the following:

(a) Within the next 25 hours time in service after the effective date of this AD, unless previously accomplished, replace the fuel control assembly support bracket with a new bracket in accordance with instructions contained in paragraph 2.B. of AiResearch Service Bulletin TPE331-73-0028, dated April 29, 1974, or later FAA-approved revisions.

(b) Within 100 hours time in service after accomplishment of paragraph (a), above, or 25 hours additional time in service after the effective date of this AD, whichever occurs later, and intervals not to exceed 100 hours time in service thereafter, inspect and retorque the fuel control assembly and support bracket mounting fasteners in accordance with the procedures contained in paragraph 2.C. of AiResearch Service Bulletin TPE331- 73-0028, dated April 29, 1974, or later FAA-approved revisions.

(c) Equivalent procedures may be approved by the Chief, Aircraft Engineering Division, FAA Western Region, upon submission of adequate substantiation data.

Note: AiResearch Operating Information Letter OI-331-3, Revision A, dated April 19, 1974, provides pertinent operational information. Flight crews are urged to obtain a copy of this letter and acquaint themselves with the information presented therein.

(d) Unless previously accomplished, within the next 1000 hours time in service, or within one year after the effective date of this AD, whichever occurs earlier, the fuel control assembly support bracket attachment lug and fastener must be modified in accordance with AiResearch Service Bulletin TPE331-73-0029, dated May 27, 1974, or later FAA-approved revisions. This change has been incorporated in production engines by model and serial number as defined in paragraph 1.A. of the above referenced service bulletin.

(e) The recurring inspection required in (b), above, may be discontinued when the modification prescribed in (d), above, have been accomplished.

(f) If the replacement of the support bracket required by paragraph (a), above, has not already been accomplished on the effective date of this amendment to the AD, this modification, when accomplished, must be done in accordance with the instructions contained in paragraph 2.B. of AiResearch Service Bulletin TPE331-73- 0028, Revision 2, dated June 20, 1975, or later FAA-approved revisions.

(g) If the replacement of the support bracket required by paragraph (a), above, has already been accomplished, at the next inspection required by paragraph (b), above, install the three (3) washers, P/N 960C10, and bolts, P/N MS21379-14, as required, per paragraph 2.B. of AiResearch Service Bulletin TPE331-73-0028, Revision 2, dated June 20, 1975, or later FAA-approved revisions.

(h) If the modification described in paragraph (d), above, has already been accomplished, before exceeding an additional 100 hours time in service after the effective date of this AD, as amended, unless already accomplished; or, when accomplishing paragraph (d), install the three (3) washers, P/N 960C10 and bolts, P/N MS21279-14, as required, per paragraph 2.B. of AiResearch Service Bulletin TPE331-73-0028, Revision 2, dated June 20, 1975, or later FAA-approved revisions.

Amendment 39-1842 became effective May 13, 1974. Amendment 39-1868 became effective June 14, 1974. This amendment 39-2253 becomes effective July 11, 1975.