Airworthiness Directive 99-17-16
recurringAirworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines
What this AD requires
This amendment adopts a new airworthiness directive (AD), applicable to Pratt & Whitney (PW) PW4000 series turbofan engines, that requires short term criteria for limiting the number of engines with potentially reduced stability on each airplane to no more than one engine, would require initial and repetitive on-wing or test cell cold-engine high pressure compressor (HPC) stability tests, would require removal of engines from service that fail on-wing test acceptance criteria, and would allow a follow-on test cell stability test. The AD also establishes required intervals for stability testing of the remaining engine with potentially reduced stability on the airplane and requirements for reporting test data. This amendment is prompted by a report of a dual-engine HPC surge event and reports of single-engine HPC surge events during the takeoff and climb phases of flight. The actions specified by this AD are intended to prevent an HPC surge event, which could result in engine power loss at a critical phase of flight such as takeoff or climb.
Which aircraft AD 99-17-16 applies to
Applies to all listed PW4000-series models regardless of modification, alteration, or repair, including Phase 3 configuration engines of any listed model. Original-manufacture PW4056, PW4156, and PW4156A engines bearing a (-3) suffix on the data-plate model designation are treated as 'first run, full up' engines with a distinct initial compliance threshold; engines converted to Phase 3 per PW SB 72-504 do not qualify.
Whether AD 99-17-16 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.