AD 70-19-02

70-19-02 AIRSEARCH: Amendment 39-1082 as amended by Amendment 39-1789. The AiResearch Manufacturing Company of Arizona. Applies to Turbopropeller Engines Model TPE331-1 and -2 installed in, but not limited to Mooney MU-2, Merlin 2B, Volpar Turboliner and Short Skyvan Aircraft.

Compliance required as indicated.

To detect impeding failure of the high speed pinion bearings accomplish the following:

(a) New engines with less than 25 hours time in service or overhauled engines with less than 25 hours time in service since overhaul on the effective date of this AD must have the following accomplished:

(1) After more than 5 hours time in service, but before exceeding 25 hours time in service after the effective date of this AD, an engine oil sample and the engine oil filter element must be returned to AiResearch Manufacturing Company, or a facility approved by the Chief, Aircraft Engineering Division, FAA, Western Region, for laboratory examination.

(2) Priorto operation of the engine in excess of 35 hours time in service, either since new or since time of overhaul, the owner or operator must receive written confirmation from AiResearch, or other approved facility, that an acceptable level of oil contamination exists.

(3) The provisions of (a)(1) and (a)(2), above, must be complied with after each subsequent overhaul unless the engine log book indicates that the engine was subjected to a 5 hour acceptance test as described in the FAA approved overhaul procedures as revised 1 September 1970, and a determination of acceptable oil and filter contamination was made by AiResearch or other FAA approved facility prior to returning the engine to service.

(4) The provisions of (a)(1), (a)(2) and (a)(3) above do not apply to engines which have been modified in accordance with either Service Bulletin 632, Revision 2, dated December 4, 1972 or Service Bulletin TPE331-72-0064 dated February 1, 1974 and which have been subjected to the acceptance test as described in the FAA-approved overhaul procedures as revised February 1, 1974, and a determination of acceptable oil filter contamination was made by AiResearch or other FAA-approved facility prior to returning the engine to service.

(b) A one time inspection of new engines with more than 25 hours but less than 50 hours time in service or overhauled engines with more than 25 hours time in service but less than 50 hours time in service since overhaul on the effective date of this AD must be accomplished:

(1) Within 10 hours time in service after the effective date of this AD conduct a visual inspection of the oil filter in accordance with the engine maintenance manual. If a significant quantity of metal particles are found, the cause must be determined before further operation.

NOTE: AiResearch Service Bulletin No. 624, dated 28 August 1970, or later FAA approved revision, lists for reference the serial number of all new or overhauled engines which had less than 50 hours time in service since new or overhaul on 28 August 1970, and describes an acceptable means of accomplishing items (a) and (b).

(c) Within 50 hours time in service after the effective date of this AD, revise the normal procedures section of the applicable FAA approved Airplane Flight Manuals for aircraft equipped with AiResearch Model TPE331-1 and -2 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."

Amendment 39-1082 became effective on September 22, 1970.

This Amendment 39-1789 becomes effective February 20, 1974.