AD/APU/20 - Hamilton Sundstrand Compressor Impeller Assemblies

This directive requires operators of Hamilton Sundstrand APUs (models T‑62T‑46C2, ‑46C2A, ‑46C3, ‑46C7, ‑46C7A) with compressor impeller P/N 4502020 or 4502020A to remove those impellers from service by specified cycles (see Requirement/Compliance). It follows two reports of uncontained impeller failures and aims to prevent APU uncontained failure and aircraft damage. Operators bear the cost and must track cycles and schedule replacements; the regulator set an effective date of 16 March 2006 and concrete removal deadlines.