73-26-07 R3: Fuel Pump Shaft Internal Drive Splines

73-26-07 R3 AIRESEARCH MANUFACTURING COMPANY OF ARIZONA: Amendment 39-1761 as amended by Amendments 39-1778 and 39-2954 is further amended by Amendment 39-3850. Applies to Model TPE331-1, -2, -3, -5, -6, -25, -29, -43, -45, -47, -51, -55, -57, -61, and TSE331-3 Series Engines. Compliance required as indicated. To detect abnormal wear of the fuel pump shaft internal drive splines and coupling shaft external splines, accomplish the following: (a) Model TPE331-3, -5, -6, and TSE331-3 Series engines which contain the grease lubricated fuel pump drive coupling spline configuration. (1) Clean, visually inspect, and lubricate the pump and coupling shaft drive splines of all engines with more than 200 hours time in service, within the next 25 hours additional time in service, unless previously accomplished within the last 375 hours time in service, and at intervals not to exceed 400 hours time in service thereafter, per the instructions and procedures described in AiResearch Service Bulletin TPE331-72-0027, Revision 4, dated November 30, 1973, or later FAA-approved revisions. If the extent of the wear is observed to exceed .003 inch, either replace the shaft with a new P/N 869911-3, or perform the additional dimensional inspection described in the Service Bulletin. If the latter inspection indicates wear beyond .005 inch, the shaft must be replaced prior to further flight. (Note: Drive Couplings, P/N 869911-1 or -2 and 895216-1, found in a serviceable condition, may be continued in service.) (2) For engines with less than 200 hours time in service since new or overhaul, clean, visually inspect and lubricate the engine by the procedures described in (a)(1) above, within 25 hours time in service after the effective date of this AD, or, prior to exceeding 200 hours time in service, whichever occurs later, and at intervals not to exceed 400 hours time in service thereafter. Replace shafts as required by the inspections. (b) Model TPE331-1, -2, -25, -29, -43, -45, -47, -51, -55, -57 and -61 Series engines which contain the grease lubricated fuel pump drive coupling spline configuration. (1) Clean, visually inspect, and lubricate the pump and coupling shaft drive splines of all engines with more than 200 hours time in service, within the next 25 hours additional time in service, unless previously accomplished within the last 775 hours, and at intervals not to exceed 800 hours time in service thereafter, per the instructions and procedures described in AiResearch Service Bulletin TPE331-72-0027, Revision 4, dated November 30, 1973, or later FAA-approved revisions. If the extent of wear is observed to exceed .003 inch, either replace the shaft with a new P/N 869911-3, or perform the additional dimensional inspection described in the Service Bulletin. If the latter inspection indicates wear beyond .005 inch, the shaft must be replaced prior to further flight. (Note: Drive Couplings, P/N 869911-1 or -2 and 895216-1, found in a serviceable condition, may be continued in service.) (2) For engines with less than 200 hours time in service since new or overhaul, clean, visually inspect and lubricate the engine by the procedures described in (b)(1) above, within 25 hours time in service after the effective date of this AD, or, prior to exceeding 200 hours time in service, whichever occurs later, and at intervals not to exceed 800 hours time in service thereafter. Replace shafts as required by the inspections. (c) If either the fuel pump, oil pump, or couplings defined in (a)(1) or (b)(1) above are replaced for any reason, a serviceable Drive Coupling, P/N 869911-3, or later FAA approved designs must be installed. (d) The initial and recurring cleaning, visual inspection and lubrication of the fuel pump and coupling shaft drive splines described in paragraph (a) and (b) above may be discontinued after incorporation of improved fuel pump shaft alignment features described in AiResearchService Bulletin TPE/TSE331-73-0051 dated April 29, 1977; TPE331-73-0054 dated April 29, 1977; TPE331-73-0056 dated May 6, 1977; or TPE331-73-0091 dated October 11, 1979; or later FAA approved revisions (as appropriate for various engine models). (e) Equivalent procedures may be approved by the Chief, Aircraft Engineering Division, FAA Western Region, upon submission of adequate substantiating data. (f) Special flight permits may be issued per FAR's 21.197 and 21.199 to authorize operation of aircraft to a base where these inspections or modifications required by this AD may be performed. Amendment 39-1761 became effective January 28, 1974. Amendment 39-1778 became effective February 1, 1974. Amendment 39-2954 became effective July 11, 1977. This Amendment 39-3850 becomes effective July 31, 1980.