AD 74-24-05

74-24-05 AIRESEARCH MANUFACTURING COMPANY OF ARIZONA: Amendment 39-2017. Applies to AiResearch Model TPE331 Series engines of the following specific models and listed serial numbers: TPE331-3U-303G; S/N 03127 through 03173 and 03176; TPE331-3UW-303G, S/N 05031 through 05042; TPE331-5-251C, S/N 22007 through 22045 and 22047 through 22050; TPE331-5-251K, S/N 06227 through 06238, 06240 through 06418 and 06420 through 06435; and, TPE 331-6-251M, S/N 20267 through 20437, 20439 through 20468 and 20470 through 20478.

In addition to the above listed serial numbers, other engines of these models which have been modified by incorporation of AiResearch Service Bulletin No. TPE331-72-0055 are also affected. To determine if this service bulletin has been accomplished, refer to the engine logbook and the engine power section nameplate. The following "Power Section Change No's" indicate incorporation of this service bulletin: TPE331-3U-303G and - 3UW-303G, Ch. No. 42; TPE331-5-251C, Ch. No. 8;TPE331-5-251K, Ch. No. 25; and TPE331-6-251M, Ch. No. 18.

Compliance required as indicated:

To detect, correct and prevent fatigue failure of the pin in the propeller pitch control sleeve assembly accomplish the following:

(A) For engines with less than 100 hours time in service or since incorporation of AiResearch Service Bulletin TPE331-72-0055: Within the next 25 hours time in service after receipt of this airmail letter, unless previously accomplished, perform the following: (1) Inspect the propeller pitch control sleeve assembly per Paragraph 2.B. or perform the vibration test per paragraph 2.C. of AiResearch Service Bulletin TPE331-72-0087, Rev. 1, dated October 29, 1974, or later FAA-approved revisions. Note: The inspection or test prescribed above need not be performed on the following listed engines since the vibration test was accomplished by the manufacturer prior to delivery: TPE331-3U-303G, S/N 03170 through 03173 and 03176; TPE331-5-251C, S/N-22047, 22048 and 22050; TPE331-5-251K, S/N 06418 and 06420 through 06435; and, TPE331-6-251M, S/N 20382, 20451, 20471 and 20473 through 20478. (2) Replace the hydraulic turbine bearing support mount retainer per paragraph 2.D. of AiResearch Service Bulletin TPE331-72-0087, Rev. 1, dated October 29, 1974, or later FAA approved revisions.

(B) For engines with more than 100 hours time in service or since incorporation of AiResearch Service Bulletin TPE331-72-0055: Within the next 300 hours time in service after receipt of this airmail letter, unless previously accomplished, accomplish the inspection or test and replacement described in (A), above.

(C) For new, overhauled or repaired engines not in service: Before placing these engines in service, after receipt of this airmail letter, unless previously accomplished, accomplish the inspection or test and replacement described in (A) above.

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

(E) Aircraft may be flown to a base for performance of maintenance required by this AD per FAR's 21.197 and 21.199."

This amendment becomes effective November 26, 1974, for all persons except those to whom it was made effective by airmail letter dated November 1, 1974.