What is the time interval between subsequent APU start attempts?

The correct interval between subsequent APU (Auxiliary Power Unit) start attempts is 2 minutes. This waiting period is crucial as it allows the APU to cool down sufficiently after an unsuccessful start attempt, preventing potential damage due to overheating or repeated electrical loads being applied in a short time frame. The 2-minute interval ensures that the components of the APU have a chance to reset and that the electrical systems have stabilized before another start attempt is made, thereby increasing the chances of a successful start during the next attempt. Adhering to this time interval is important for the longevity of the APU and for operational safety purposes.