AD 79-16-06

79-16-06 DETROIT DIESEL ALLISON: Amendment 39-3527 is further amended by Amendment 39- 3650. Applies to all Model 250-C28 and 250-C30 series engines equipped with generator idler gearshaft P/N 6898980, or 6898591, or 77 tooth spur idler gearshaft P/N 6898652 installed in, but not limited to Bell 206L-1 and Sikorsky S-76 rotorcraft certificated in all categories. Compliance required as indicated unless previously accomplished. To preclude engine power loss as a result of an accessory drive gearbox failure, remove the referenced gearshafts from service prior to reaching 9000 cycles if installed in a 250-C28 series engine and prior to reaching 2000 cycles if installed in a 250-C30 engine. For those gearshafts that are within 50 cycles of the appropriate limit on the effective date of this AD, compliance is required within 100 cycles. For the purpose of this AD, a cycle is defined as an attempted or completed start, or a motoring of the engine using the starter. The start counter is activated and accumulates the count of cycles only when the ignition circuit is energized. Therefore, cycles due to motoring with the starter (ignition circuit not energized) must be added to the cycle count. (Detroit Diesel Allison Commercial Engine Bulletins CEB 72-2003 for the 250-C28B and CEB 72-3003 for the 250-C30 also pertain to this subject.) Amendment 39-3527 became effective August 15, 1979. This amendment 39-3650 becomes effective January 11, 1980.