Airworthiness Directive · Amendment 39-17148 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to the following Pratt & Whitney Division turbofan engines:
(1) PW4052, PW4152, and PW4056 turbofan engines, including models with any dash number suffix, with a high-pressure turbine (HPT) stage 1 front hub part number (P/N) listed in Table 1 to paragraph (c) of this AD installed.
(2) PW4156A, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4158, PW4460, and PW4462 turbofan engines, including models with any dash number suffix, with an HPT stage 1 front hub P/N listed in Table 1 to paragraph (c) of this AD installed.
| P/N 51L601 | All serial numbers (S/Ns). |
| P/N 52L401 | With a S/N not listed in Table 5 of the Accomplishment Instructions of Pratt & Whitney Alert Service Bulletin (ASB) No. PW4ENG A72-821, dated July 6, 2012. |
| P/N 51L201, P/N 51L201-001, P/N 51L201-021 | All S/Ns. |
| P/N 51L901, P/N 52L301 | With an S/N not listed in Table 7 of the Accomplishment Instructions of Pratt & Whitney ASB No. PW4ENG A72-821, dated July 6, 2012. |
(3) PW4164, PW4164C, PW4164C/B, PW4168, and PW4168A turbofan engines with an HPT stage 1 front hub, P/N 51L901, installed with an S/N not listed in Table 3 of the Accomplishment Instructions of Pratt & Whitney ASB No. PW4G-100-A72-246, dated June 28, 2012.
We are adopting a new airworthiness directive (AD) for Pratt & Whitney Division PW4052, PW4152, PW4056, PW4156A, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4158, PW4460, PW4462, PW4164, PW4164C, PW4164C/B, PW4168, and PW4168A turbofan engines with certain high- pressure turbine (HPT) stage 1 front hubs installed. This AD was prompted by Pratt & Whitney's updated low-cycle-fatigue analysis that indicated certain HPT stage 1 front hubs could initiate a crack prior to the published life limit. This AD requires removing the affected HPT stage 1 front hubs from service using a drawdown plan. We are issuing this AD to prevent failure of the HPT stage 1 front hub, which could lead to an uncontained engine failure and damage to the airplane.
(1) For HPT stage 1 front hubs listed in paragraph (c)(1) of this AD, do the following:
(i) If the HPT stage 1 front hub has accumulated 17,000 or fewer cycles-since-new (CSN) on the effective date of this AD, remove the HPT stage 1 front hub from service before accumulating 18,000 CSN.
(ii) If the HPT stage 1 front hub has accumulated more than 17,000 CSN on the effective date of this AD, remove the HPT stage 1 front hub from service before accumulating an additional 1,000 cycles-in-service (CIS) or at the next piece-part exposure above 18,000 CSN, whichever occurs first.
(2) For HPT stage 1 front hubs listed in paragraphs (c)(2) and (c)(3) of this AD, do the following:
(i) If the HPT stage 1 front hub has accumulated 12,700 or fewer CSN on the effective date of this AD, remove the HPT stage 1 front hub from service before accumulating 13,700 CSN.
(ii) If the HPT stage 1 front hub has accumulated more than 12,700 CSN on the effective date of this AD, remove the HPT stage 1 front hub from service before accumulating an additional 1,000 CIS or at the next piece-part exposure above 13,700 CSN, whichever occurs first.
After the effective date of this AD, do not install into any engine any HPT stage 1 front hubs listed in paragraph (c)(1) of this AD that are at piece-part exposure and exceed 18,000 CSN, or any HPT stage 1 front hubs listed in paragraphs (c)(2) and (c)(3) of this AD that are at piece-part exposure and exceed 13,700 CSN.
For the purpose of this AD, piece-part exposure means that the part is completely disassembled and removed from the engine.
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.
