Airworthiness Directive · Amendment 39-19163 · Turbine engine combustion section
Pratt & Whitney Division Turbofan Engines
Superseded. A later AD replaced this one: AD 2023-22-02. Comply with the one in force.
This AD applies to all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines with outer diffuser case, part number (P/N) 50J775 or P/N 50J930, installed.
We are adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. This AD was prompted by the discovery of multiple cracked outer diffuser cases. This AD requires initial and repetitive inspections to detect cracks in the outer diffuser case and removal from service of cases that fail inspection. We are issuing this AD to address the unsafe condition on these products.
(1) Perform an initial high sensitivity fluorescent penetrant inspection (FPI) of the outer diffuser case T3 thermocouple probe boss (Tt3 boss) prior to accumulating 13,000 cycles since new (CSN), or within 1,000 flight cycles from the effective date of this AD, whichever occurs later. If the case CSN is unknown, inspect within 1,000 flight cycles from the effective date of this AD.
(2) Thereafter, repeat the high sensitivity FPI of the outer diffuser case Tt3 boss within 2,000 flight cycles since the last FPI.
(3) If an indication is found during the inspections required by paragraphs (g)(1) or (2) of this AD, re-inspect or remove the outer diffuser case from service as follows:
(i) For engines installed on-wing, re-inspect or remove in accordance with the Accomplishment Instructions, Part A, paragraph 1.G., of PW ASB PW4G-112-A72-347, dated March 31, 2017.
(ii) For assembled engines not installed on-wing, re-inspect or remove in accordance with the Accomplishment Instructions, Part B, paragraph 1.C., of PW ASB PW4G-112-A72-347, dated March 31, 2017.
(iii) For disassembled engines, if any cracks are found, remove the outer diffuser case from service before further flight.
(4) Within 30 days of the effective date of this AD, update the mandatory inspections of the Airworthiness Limitations Section (ALS) of your Instructions for Continued Airworthiness to include the piece-part inspections of the diffuser case as defined in Figure 1 to paragraph (g) of this AD.
