Airworthiness Directive · Amendment 39-18185 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to all Pratt & Whitney Division (PW) PW6122A and PW6124A turbofan engines with high-pressure compressor (HPC) 7th stage integrally bladed (IB) rotor, part number (P/N) 5495637, installed.
We are adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW6122A and PW6124A turbofan engines. This AD requires initial and repetitive borescope inspections (BSIs) of the high-pressure compressor (HPC) 7th stage integrally bladed (IB) rotor aft integral arm for cracks until replacement of the HPC 7th stage IB rotor using non-silver-plated nuts. This AD was prompted by reports of crack finds in the HPC 7th stage IB rotor. We are issuing this AD to prevent HPC 7th stage IB rotor fractures, which could lead to uncontained engine failure and damage to the airplane.
(1) Within 180 cycles after the effective date of this AD or within 6,500 cycles accumulated on the HPC 7th stage IB rotor, whichever occurs later, borescope inspect the HPC 7th stage IB rotor for cracks. Use Appendix 1, paragraphs 5 and 6 of PW Engineering Authorization 15MM008, Revision A, dated March 24, 2015, to do your inspection. Thereafter, repeat the inspection at every 1,000 cycles since last inspection.
(2) If any crack is detected on the HPC 7th stage IB rotor, then before further flight, replace the HPC 7th stage IB rotor with a part eligible for installation.
(1) At the next shop visit after the effective date of this AD:
(i) Replace the affected HPC 7th stage IB rotor, P/N 5495637, with a new, zero-time, HPC 7th stage IB rotor, P/N 5495637, and
(ii) Remove the HPC 7th stage IB rotor silver-plated nuts, P/N 4301682, and replace with non-silver-plated nuts. Use the Accomplishment Instructions of PW Service Bulletin No. PW6ENG 72-46, dated March 5, 2015 to perform the removal and replacement.
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 pairs of major mating engine flanges. The separation of engine flanges solely for the purposes of transportation without subsequent engine maintenance, is not an engine shop visit.
