What is the proper APU psi when temperatures drop below -15 degrees F?

The proper APU (Auxiliary Power Unit) psi when temperatures drop below -15 degrees Fahrenheit is 2900 psi. This psi level is critical to ensure that the APU operates efficiently in lower temperatures. As temperatures decrease, the required psi increases to maintain optimal performance and reliability of the APU system.

By setting the psi at 2900, it provides sufficient pressure to facilitate fuel operation and ignite the APU effectively, ensuring that it can supply the necessary electrical power and air for engine starting and other functions even in colder climates. Maintaining this pressure standard is essential for operational safety and efficiency of the aircraft systems in adverse weather conditions.