AD 71-05-07

71-05-07 AIRESEARCH: Amdt. 39-1166 as amended by Amendment 39-1180 and 39-1277 is further amended by Amendment 39-1430. The AiResearch Manufacturing Company of Arizona. Applies to Turbopropeller Engines Model TPE331-1, -2, -25, -29, -43, -45, -47, -49, -51, -55, -57, -61 and -71 installed in, but not limited to the Mitsubishi MU-2, Swearingen Merlin 2B, Volpar Turboliner and Short Skyvan Aircraft.

Compliance required as indicated.

To prevent possible failure of the high speed pinion assembly, accomplish the following:

(a) Within 50 hours time in service after the effective date of this amendment to AD 71-05-07, as amended, unless already accomplished, and at intervals not to exceed 50 hours time in service thereafter, perform a visual inspection of the engine oil filter per AiResearch Service Bulletin 628, Revision 2, dated March 23, 1972, or later FAA-approved revision, or an equivalent inspection approved by the Chief, Aircraft Engineering Division, FAA Western Region. Return a sample of engine oil and the used engine oil filter element after each inspection to AiResearch for laboratory examination in accordance with AiResearch Service Bulletin 628, Revision 2, dated March 23, 1972, or later FAA-approved revision. Use of other laboratory facilities requires the approval of the Chief, Aircraft Engineering Division, FAA Western Region. Operators must submit substantiating data to obtain this approval.

(1) If excessive oil contamination in the filter is found during the visual inspection required in (a) above, the cause must be determined and corrected before further flight.

(2) Prior to operation of the engine in excess of 50 hours time in service since the inspection prescribed in (a) above, the owner or operator must receive written confirmation of the results from AiResearch, or another approved facility.

(b) Within 50 hours' time in service after the effective date of this AD, unless already accomplished, revise the normal procedures section of the applicable FAA approved Airplane Flight Manuals for aircraft equipped with AiResearch Model TPE331-1, -2, -25, -29, -43, -45, -47, -49, -51, -55, -57, -61, and -71 series engines to include a cautionary note to read as follows:

"If sudden loss or significant fluctuation of torque pressure indication occurs, the engine should be promptly shut down and the cause determined before further operation."

(c) After the effective date of this amendment to AD 71-05-07, as amended, unless previously accomplished, incorporate, at the next engine overhaul, the improved high speed pinion and thrust washer assembly per AiResearch Service Bulletin 632, Revision 1, dated March 23, 1972, or Service Bulletin 659, Revision 1, dated March 23, 1972, or later FAA-approved revision(s), or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA Western Region. Upon completion of this modification the inspections of (a) above may be discontinued, and the AFM revision required by (b), above, may be deleted.

Amendment 39-1166 became effective on March 9, 1971. Amendment 39-1180 became effective on April 6, 1971. Amendment 39-1277 became effective on September 2, 1971. This Amendment 39-1430 becomes effective on April 8, 1972.