Summary
The FAA proposes to adopt a new airworthiness directive (AD) for Hamilton Sundstrand Power Systems Models T-62T-46C12 and T-62T-40C14 (APS 500R) APUs with fuel filter housing assembly, part numbers (P/Ns) 4951627, 4951960, or 4952039, installed. This proposed AD would require installation of a bracket to prevent a failed bypass button from protruding beyond the internal o-ring seal. This proposed AD results from reports of leaks caused by cracked bypass buttons that protruded beyond the o-ring seal. We are proposing this AD to prevent a fire or explosion caused by a fuel leak from a failed bypass button on the fuel filter housing.