Airworthiness Directive · Amendment 39-13879 · Hamilton Sundstrand Power Systems T-62T Series Auxiliary Power Units (APUs)
Hamilton Sundstrand Power Systems T-62T Series Auxiliary Power Units (APUs)
This AD applies to Hamilton Sundstrand Power Systems Models T-62T-46C12 and T-62T-40C14 (APS 500R) auxiliary power units (APUs) with fuel filter housing assemblies, part numbers (P/Ns) 4951627, 4951960, or 4952039, installed. These APUs are installed on, but not limited to, Bombardier DHC-8-400 airplanes and Empresa Brasileira de Aeronautica S.A. (EMBRAER) EMB-135 and -145 series airplanes.
The FAA is adopting 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 number (P/N) 4951627, 4951960, or 4952039, installed. This AD requires installation of a bracket to prevent a failed bypass button from protruding beyond the internal o-ring seal. This AD results from reports of leaks caused by cracked bypass buttons that protruded beyond the o-ring seal. We are issuing this AD to prevent a fire or explosion caused by a fuel leak from a failed bypass button on the fuel filter housing.
You are responsible for having the actions required by this AD performed within 500 hours time-in-service or 6 months after the effective date of this AD, whichever occurs earlier, unless the actions have already been done.
Install a bracket onto the fuel filter housing assembly on APU Model T-62T-46C12. Use 2.A through 2.D of the Accomplishment Instructions of Hamilton Sundstrand Alert Service Bulletin (ASB) No. ASB-4503067-49-9, dated December 2, 2003, to install the bracket.
Install a bracket onto the fuel filter housing assembly on APU Model T-62T-40C14 (APS 500R). Use 2.B. and 2.D.(1) of the Accomplishment Instructions of Hamilton Sundstrand ASB No. ASB-4504112-49-22, Revision 2, dated October 4, 2004, to install the bracket.
Previous credit is allowed for brackets installed using Hamilton Sundstrand ASB No. ASB-4503067-49-9, dated December 2, 2003, Hamilton Sundstrand ASB No. ASB-4504112-49-22, Original, dated December 2, 2003, or Revision 1, dated January 5, 2004, before the effective date of this AD.
(i) For brackets previously installed using Hamilton Sundstrand ASB No. ASB-4504112-49-22, Original, dated December 2, 2003, perform a one-time inspection for proper gap and if necessary, adjust the gap between the bracket and bypass button. Use 2.B. and 2.D.(1) of the Accomplishment Instructions of Hamilton Sundstrand ASB No. ASB-4504112-49-22, Revision 2, dated October 4, 2004 to inspect and adjust the gap.
For APU Model T-62T-40C14 (APS 500R), installation of a part number fuel filter assembly that is not listed in this AD constitutes optional terminating action to the requirements of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Appliances and equipment
