Airworthiness Directive · Amendment 39-14959 · Pratt & Whitney PW4077D, PW4084D, PW4090, and PW4090-3 Turbofan Engines
Pratt & Whitney PW4077D, PW4084D, PW4090, and PW4090-3 Turbofan Engines
This AD applies to Pratt & Whitney PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines that were:
(1) Reassembled with a previously used original equipment manufacturer (OEM) or part manufacturer approval (PMA) high pressure compressor (HPC) exit inner brush seal pack; and
(2) Reassembled with a new or refurbished OEM or PMA HPC exit diffuser air seal inner land.
(d) These engines are installed on, but not limited to, Boeing 777 airplanes.
The FAA is superseding an existing airworthiness directive (AD) for Pratt & Whitney PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines that were reassembled with previously used high pressure compressor (HPC) exit brush seal packs and new or refurbished HPC exit diffuser air seal lands. That AD currently requires replacing the HPC exit inner and outer brush seal packs with new brush seal packs, or replacing the HPC exit brush seal assembly with a new HPC exit brush seal assembly. This AD requires replacing the HPC exit inner and outer brush seal packs with new brush seal packs, using either original equipment manufactured (OEM) parts, or FAA-approved part manufacturer approval (PMA) parts. This proposed AD also applies to engines reassembled with a PMA HPC exit inner and or outer brush seal packs. This AD results from a request to include PMA HPC exit inner and outer brush seal packs and to include the engines with PMA parts already installed, in the AD. We are issuing this AD to prevent uncontained engine failure, damage to the airplane, and injury to passengers.
You are responsible for having the actions required by this AD performed at the following compliance times, unless the actions have already been done.
(g) Replace the HPC exit inner and outer brush seal packs with OEM or FAA-approved PMA new HPC exit inner and outer brush seal packs, or an OEM or FAA-approved PMA new HPC exit brush seal assembly, as follows:
(1) By 3,000 cycles-in-service (CIS) since a used HPC exit inner brush seal pack and a new or refurbished HPC exit diffuser air seal land were installed in the engine, or by March 31, 2007, whichever occurs later; however
(2) If on March 31, 2007, the used HPC exit inner brush seal pack coupled with a new or refurbished HPC exit diffuser air seal inner land assembly has not accumulated 3,000 CIS, then by 3,000 CIS, or December 31, 2008, whichever occurs first.
Engine reassembly with used OEM or used FAA-approved PMA HPC exit inner and outer brush seal packs with OEM or FAA-approved PMA new HPC exit inner and outer brush seal lands, is prohibited.
(i) Information on replacing HPC exit inner and outer brush seal packs can be found in the Pratt & Whitney Alert Service Bulletin No. PW4G-112-A72-280, Revision 2, dated January 12, 2007, and in the engine overhaul manual.
