Airworthiness Directive · Amendment 39-21640 · Turbine section
Pratt & Whitney Turbofan Engines
This AD applies to all Pratt & Whitney (PW) PW2037, PW2037M, PW2040, and F117-PW-100 model turbofan engines.
The FAA is adopting a new airworthiness directive (AD) for all Pratt & Whitney (PW) PW2037, PW2037M, PW2040, and F117-PW-100 model turbofan engines. This AD was prompted by a report of an uncontained engine failure resulting from cracks in the knife edge of the high- pressure turbine (HPT) 2nd-stage air seal assembly. This AD requires fluorescent penetrant inspections (FPIs) and visual inspections of the HPT 2nd-stage air seal assembly and, depending on the results of the inspections, replacement of the HPT 2nd-stage air seal assembly with a part eligible for installation. This AD also requires replacement of the affected HPT 2nd-stage air seal assembly, depending on the engine model, at either the next engine shop visit or the next piece-part opportunity. The FAA is issuing this AD to address the unsafe condition on these products.
After the effective date of this AD, at every piece-part opportunity of the HPT 1st-stage disk, HPT 2nd-stage hub, or the HPT 2nd-stage air seal assembly:
(i) Perform a visual inspection of the HPT 2nd-stage air seal assembly, strip the knife edge coating from the HPT 2nd-stage air seal assembly, and then perform an FPI of the HPT 2nd-stage air seal assembly.
Note 1 to paragraph (g)(1)(i): Guidance on striping the knife edge coating from the HPT 2nd-stage air seal assembly required by paragraph (g)(1)(i) of this AD can be found Chapter 72-52-60, Repair-01, of the PW2000 Series Engine Manual.
(ii) If a crack is found in the HPT 2nd-stage air seal assembly during the visual inspection or FPI required by paragraph (g)(1)(i) of this AD, remove the HPT 2nd-stage air seal assembly from service and replace it with a part eligible for installation.
(iii) During the visual inspection or FPI required by paragraph (g)(1)(i) of this AD, if a crack is found in the shaded regions of the HPT 2nd-stage air seal assembly identified in Figure 1 to paragraph (g)(1)(iii) of this AD (Figure 1), which extends towards the knife-edge region of the HPT 2nd-stage air seal assembly, remove the HPT 2nd-stage air seal assembly, mating HPT 1st-stage disk, and HPT 2nd-stage hub from service, and replace the parts with parts eligible for installation. In order to return the mating HPT 1st-stage disk and HPT 2nd-stage hub to service, the inspections of the HPT 2nd-stage air seal assembly cannot reveal a crack identified in the shaded regions of Figure 1, which extends towards the knife-edge region.
(i) For PW PW2037, PW2037M, and PW2040 model turbofan engines, at the next engine shop visit after the effective date of this AD, remove the HPT 2nd-stage air seal assembly, part number (P/N) 1A8209 or 1A8209-001, and replace it with a part eligible for installation.
(ii) For PW F117-PW-100 model turbofan engines, at the next piece part opportunity after the effective date of this AD, remove the HPT 2nd-stage air seal assembly, P/N 1A8209 or 1A8209-001, and replace it with a part eligible for installation.
(1) For the purpose of this AD, an “engine shop visit” is the induction of an engine into the shop for maintenance involving the separation of the N or M engine flange. The separation of engine flanges solely for the purposes of transportation of the engine without subsequent engine maintenance does not constitute an engine shop visit.
(2) For the purpose of this AD, a “piece-part opportunity” is:
(i) For the HPT 1st-stage disk, when the disk is removed from the engine and all the blades are removed;
(ii) For the HPT 2nd-stage hub, when the hub is removed from the engine and all the blades are removed; or
(iii) For the HPT 2nd-stage air seal assembly, when the assembly is removed from either the HPT 1st-stage disk or the HPT 2nd-stage hub.
(3) For the purpose of this AD, a “part eligible for installation” is an HPT 2nd-stage air seal assembly with a P/N other than 1A8209 or 1A8209-001.
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.
