Summary
The FAA proposes to supersede 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 proposed AD would require 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) equivalent parts. This proposed AD would also apply to engines reassembled with a PMA equivalent HPC exit inner and/or outer brush seal packs. This proposed AD results from a request to include PMA equivalent HPC exit inner and outer brush seal packs and to include the engines with PMA equivalent parts already installed, in the AD. We are proposing this AD to prevent uncontained engine failure, damage to the airplane, and injury to passengers.