Airworthiness Directive · Amendment 39-18017 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engine models with second-stage high-pressure turbine (HPT) air seal, part number (P/N) 54L041, 50L960, or 50L976, installed.
The FAA is correcting an airworthiness directive (AD) that published in the Federal Register. That AD applies to all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engine models with certain second-stage high-pressure turbine (HPT) air seals installed. The time required to perform the initial eddy current inspection (ECI) in the Compliance section is incorrect. This document corrects that error. In all other respects, the original document remains the same.
(1) At the next piece-part exposure after the effective date of this AD, do the following:
(i) Remove from service second-stage HPT air seals, P/Ns 50L960, 50L976, and 54L041.
(ii) Perform a fluorescent-penetrant inspection (FPI) of the second-stage HPT air seal, P/N 54L041, for a through-crack in the front forward fillet radius.
(iii) If a through-crack in the front forward fillet radius is found, remove the first-stage HPT hub, second-stage HPT hub, and second-stage HPT blade retaining plate from service. Do not reinstall the first-stage HPT hub, second-stage HPT hub, or second-stage HPT blade retaining plate into any engine.
(2) For engines with second-stage HPT air seals, P/N 54L041, installed, perform initial and repetitive inspections for cracks on-wing until the part is removed from the engine as follows:
(i) Perform an initial eddy current inspection (ECI) for cracks before reaching 2,200 cycles since new, within 1,000 cycles-in-service after September 17, 2013, or before further flight, whichever occurs later.
(ii) Thereafter, repeat the ECI every 1,200 cycles since last inspection, or fewer, depending on the results of the inspection.
(iii) Use section 4.0 of the appendix of PW Alert Service Bulletin (ASB) No. PW4G-112-A72-330, Revision 2, dated July 11, 2013, to perform the inspection and use paragraph 8 of the Accomplishment Instructions of PW ASB No. PW4G-112-A72-330, Revision 2, dated July 11, 2013, to disposition the results of the inspection.
(1) After the effective date of this AD, do not install any second-stage HPT air seal, P/N 54L041, P/N 50L960, or P/N 50L976, into any engine.
(2) After the effective date of this AD, do not install any spare first-stage HPT hub, second-stage HPT hub, or second-stage HPT blade retaining plate that was previously mated in service to a second-stage HPT air seal, P/N 54L041, that was found to have a through-crack in the front forward fillet radius, into any engine.
For the purpose of this AD:
(1) Piece-part exposure is when the second-stage HPT air seal is removed from the engine and fully disassembled.
(2) A through-crack is a crack that has propagated through the thickness of the part and can be seen on both the inner diameter and outer diameter of the front forward fillet radius.
