Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C, and -219 turbofan engines. That AD currently requires initial and repetitive visual inspections for fretting and fluorescent magnetic particle inspections (FMPI) for cracking in the area of the tierod holes on 8th stage high pressure compressor (HPC) front hubs (from here on, referred to as HPC front hubs) that have operated at any time with PWA 110-21 coating. This proposed AD would require either replacing HPC front hubs and HPC disks that have operated at any time with PWA 110-21 coating and that operated in certain engine models, or, visually inspecting and FMPI for cracking of those parts and replating them if they pass inspection. This proposed AD would also require adding JT8D- 1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, 17A, 17R, and 17AR engines to the applicability. This proposed AD results from an investigation by PW, which concluded that any HPC front hub or HPC disk coated with PWA 110-21 that ever operated on JT8D-15, -15A, -17, -17A, -17R, -17AR, -209, -217, -217A, -217C, and -219 turbofan engines, could crack before reaching their published life limit. We are proposing this AD to prevent a rupture of an HPC front hub or an HPC disk that could result in an uncontained engine failure and damage to the airplane.