Summary
The FAA proposes to adopt a new airworthiness directive (AD). The new AD is for Hamilton Sundstrand Power Systems (formerly Sundstrand Power Systems) auxiliary power units (APUs) models T-62T- 46C2, T-62T-46C2A, T-62T-46C3, T-62T-46C7, and T-62T-46C7A, with compressor impeller assembly, part number (P/N) 4502020 or 4502020A, installed. This proposed AD would require removal from service of those compressor impeller assemblies at reduced service life limits. This proposed AD results from two reports of uncontained failures of compressor impeller assemblies. We are proposing this AD to prevent an uncontained APU failure and damage to the airplane.