Airworthiness Directive · Amendment 39-16999 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to all Pratt & Whitney PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, and PW4650 turbofan engines, including models with any dash number suffix, that have not incorporated Pratt & Whitney Alert Service Bulletin (ASB) No. PW4ENG-A72-436; Service Bulletin (SB) No. PW4ENG-79-76; and SB No. PW4ENG-72-472.
We are adopting a new airworthiness directive (AD) for all Pratt & Whitney PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, and PW4650 turbofan engines, including models with any dash number suffix. This AD was prompted by reports of five engine in-flight shutdowns and seven unplanned engine removals. This AD requires inspections, cleaning, and engine modifications to address coking in the No. 4 bearing compartment and in the oil pressure and scavenge tubes. We are issuing this AD to prevent an engine fire, a fractured fan drive shaft, and damage to the airplane.
(1) If you have incorporated Pratt & Whitney ASB No. PW4ENG-A72-436; SB No. PW4ENG-79-76; and SB No. PW4ENG-72-472, then no further action is required.
(2) Comply with this AD within the compliance times specified, unless already done.
(1) Within 1,000 cycles-in-service (CIS) after the effective date of this AD, inspect and clean the No. 4 bearing compartment.
(2) Thereafter, within every additional 1,000 CIS, re-inspect and clean the No. 4 bearing compartment.
At the next engine shop visit, but not to exceed 5 years after the effective date of this AD, do the following:
(1) Replace the No. 4 bearing packing transfer tube assembly;
(2) Replace the No. 4 bearing internal scavenge tube assembly;
(3) Remove the No. 4 bearing shield, and the No. 4 bearing shield option; and
(4) Install the new No. 4 bearing shield options.
(5) Modify the turbine exhaust case to relocate the No. 4 bearing pressure and scavenge tube ports to below the engine centerline;
(6) Replace the internal No. 4 bearing pressure and scavenge tubes;
(7) Modify or replace the turbine case cooling brackets to support the new No. 4 bearing pressure and scavenge tubes;
(8) Replace the turbine case manifolds as necessary; and
(9) Install the new brackets and clamps to support the new routing configuration.
Performing the modifications specified in paragraphs (g)(1) through (g)(9) of this AD is terminating action for the repetitive inspections and cleanings specified in paragraph (f)(2) of this AD.
For the purpose of this AD, a shop visit is when the engine is inducted into the shop for any maintenance involving the separation of pairs of major mating engine flanges (lettered flanges). However, the separation of engine flanges solely for the purposes of transporting the engine without subsequent engine maintenance is not an engine shop visit.
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.
