Airworthiness Directive · Amendment 39-14148 · General Electric Company CT64-820-4 Turboprop Engines
General Electric Company CT64-820-4 Turboprop Engines
This AD applies to General Electric Company (GE) CT64-820-4 turboprop engines with stage 1 turbine disk and shaft, part number (P/N) 6004T47P03 or 4921T10P02 installed. These engines are installed on, but not limited to, DeHavilland DHC-5D Buffalo airplanes.
The FAA is adopting a new airworthiness directive (AD) for General Electric Company (GE) CT64-820-4 turboprop engines with stage 1 turbine disk and shaft, part number (P/N) 6004T47P03 or 4921T10P02 installed. This AD requires removing from service these stage 1 turbine disk and shafts at reduced compliance times. This AD results from the discovery by the manufacturer of low-cycle-fatigue (LCF) cracks found in stage 1 turbine disk and shafts, P/Ns 6004T47P03 and 4921T10P02. We are issuing this AD to prevent uncontained failure of the stage 1 turbine disk and shaft, resulting in damage to the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
For engine serial number (SN) 268537, remove the stage 1 turbine disk and shaft from service at or before accumulating 1,700 cycles-since-new (CSN), or by December 31, 2005, whichever occurs first.
(g) For engine SN 268565, remove the stage 1 turbine disk and shaft from service at or before accumulating 1,585 CSN, or by December 31, 2005, whichever occurs first.
(h) For engine SN 268637, remove the stage 1 turbine disk and shaft from service at or before accumulating 1,345 CSN, or by December 31, 2005, whichever occurs first.
(i) For all other engines that have accumulated 590 CSN or more on the stage 1 turbine disk and shaft on the effective date of this AD, remove stage 1 turbine disk and shaft from service at or before accumulating an additional 10 cycles-in-service, at or before accumulating the service life limit of 1,700 CSN, or by December 31, 2005, whichever occurs first.
(j) For all other engines that have accumulated fewer than 590 CSN on the stage 1 turbine disk and shaft on the effective date of this AD, remove stage 1 turbine disk and shaft from service at the next piece-part-exposure, or before accumulating 600 CSN, or by December 31, 2005, whichever occurs first.
(k) After the effective date of this AD, do not install any stage 1 turbine disk and shaft, P/N 6004T47P03 or 4921T10P02, into any engine.
(l) After the effective date of this AD, do not install any engine with stage 1 turbine disk and shaft, P/N 6004T47P03 or 4921T10P02, into any airplane.
For the purpose of this AD, piece-part exposure is defined as the stage 1 disk and shaft is completely disassembled using the disassembly instructions of the manufacturer's engine manual, or other FAA-approved engine manual.
