Airworthiness Directive · Amendment 39-16960 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to all Pratt & Whitney Division PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, and PW4650 turbofan engines, including models with any dash number suffix, with a Pratt & Whitney fuel metering unit (FMU) part number (P/N) 53T335 (HS 801000-1), 55T423 (HS 801000-2), or 50U150 (HS 801000-3) installed.
We are adopting a new airworthiness directive (AD) for all Pratt & Whitney PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, and PW4650 turbofan engines, including models with any dash number suffix. This AD was prompted by an engine overspeed event that occurred during taxi and resulted in a high-pressure compressor surge and tailpipe fire. This AD requires replacing Pratt & Whitney fuel metering units (FMUs), part numbers (P/Ns) 53T335 (HS 801000-1), 55T423 (HS 801000-2), and 50U150 (HS 801000-3) at the next shop visit after the effective date of this AD. We are issuing this AD to prevent engine overspeed on these engines, which could result in an uncontained engine failure and damage to the airplane.
At the next shop visit after the effective date of this AD, remove FMU P/Ns 53T335 (HS 801000-1), 55T423 (HS 801000-2), and 50U150 (HS 801000-3) and install an FMU that incorporates the modification in paragraphs 3.C through 3.E of the Accomplishment Instructions of Hamilton Sundstrand Alert Service Bulletin (ASB) No. JFC131-2-73-A24, Revision 1, dated May 18, 2011.
After three years from the effective date of this AD, do not install or reinstall an FMU P/N 53T335 (HS 801000-1), 55T423 (HS 801000-2), or 50U150 (HS 801000-3) onto any engine.
For the purpose of this AD, a shop visit is when the engine is inducted into the shop for any maintenance involving the separation of pairs of major mating engine flanges (lettered flanges). However, the separation of engine flanges solely for the purposes of transporting the engine without subsequent engine maintenance is not an engine shop visit.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
