Summary
The FAA proposes to adopt a new airworthiness directive (AD) for Hamilton Sundstrand Power Systems T-62T-46C12 auxiliary power units (APUs). This proposed AD would require upgrading the software in the APU full-authority digital controller (FADEC), from software version 02.01.000 to version 03.00.000. This proposed AD results from two reports of APU compartment explosions due to over-fueling of the APU at low rpm during the start sequence. We are proposing this AD to prevent over-fueling of the APU during the start sequence, which could lead to fuel explosions, injury, and damage to the APU and the airplane.