Airworthiness Directive · Amendment 39-15808 · Pratt & Whitney PW4090 and PW4090-3 Turbofan Engines
Pratt & Whitney PW4090 and PW4090-3 Turbofan Engines
This AD applies to Pratt & Whitney (PW) PW4090 and PW4090-3 turbofan engines with front turbine hub part number (P/N) 53L601, (part of assembly P/N 53L121), installed. These engines are installed on, but not limited to, Boeing 777-200 series and 777-300 series airplanes.
The FAA is adopting a new airworthiness directive (AD) for Pratt & Whitney (PW) PW4090 and PW4090-3 turbofan engines with front turbine hub, part number (P/N) 53L601, installed. This AD reduces the published life limit of those front turbine hubs, from 12,000 cycles- since-new (CSN) to 9,370 CSN. This AD also removes from service those front turbine hubs using a drawdown schedule. This AD results from PW updating the low-cycle-fatigue (LCF) life analysis for front turbine hubs, P/N 53L601. We are issuing this AD to prevent an uncontained failure of the front turbine hub, resulting in an in-flight engine shutdown and possible 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.
(f) Remove front turbine hub, P/N 53L601 (part of assembly P/N 53L121), from service and install a serviceable front turbine hub, as follows:
(1) For front turbine hubs that have accumulated fewer than 3,370 cycles-since-new (CSN) on the effective date of this AD, remove from service before the hub accumulates 9,370 CSN.
(2) For front turbine hubs that have accumulated 3,370 or more CSN, but fewer than 9,370 CSN on the effective date of this AD, do the following:
(i) For engines that have an engine shop visit (ESV) after the effective date of this AD before the front turbine hub accumulates 9,370 CSN, remove the front turbine hub from service before the front turbine hub accumulates 9,370 CSN.
(ii) For engines that do not have an ESV after the effective date of this AD before the front turbine hub accumulates 9,370 CSN, remove the front turbine hub from service at the next ESV, or before the hub accumulates an additional 6,000 cycles-since-last-fluorescent-penetrant inspection of the front turbine hub, whichever occurs first, but not to exceed 12,000 CSN.
(3) For front turbine hubs that have accumulated 9,370 or more CSN on the effective date of this AD, remove the front turbine hub from service at the next ESV, or before the hub accumulates 12,000 CSN, whichever occurs first.
(g) This AD establishes a new reduced published life limit for the PW4090 turbine front hub, P/N 53L601, of 9,370 CSN. The following conditions also apply:
(1) Except as provided in paragraphs (f)(2)(ii) and (f)(3) of this AD, no alternative retirement lives may be approved for the PW4090 front turbine hub, P/N 53L601.
(2) After the effective date of this AD, do not install or reinstall any PW4090 front turbine hub, P/N 53L601, on any engine if the hub has accumulated 9,370 CSN or more than 9,370 CSN. Any PW4090 front turbine hub, P/N 53L601, that is installed or re-installed in any engine after the effective date of this AD must be removed from service before the hub accumulates 9,370 CSN.
For the purposes of this AD, an “engine shop visit” is the induction of an engine into the shop for maintenance involving the separation of any major mating engine flange aft of the “B” flange, except that the separation of engine flanges solely for the purposes of transportation without subsequent engine maintenance does not constitute an engine shop visit.
