What is the primary purpose of the APU load control valve?

The primary purpose of the APU load control valve is to protect the APU (Auxiliary Power Unit) from an overtemperature condition. The load control valve helps to regulate the temperature and pressure within the APU system. When the APU operates, it generates heat, and if that heat is not managed properly, it can lead to overheating which may cause damage to the unit. The load control valve works by modulating the load on the APU; if the temperature approaches a critical threshold, the valve can reduce the load or shut off fuel flow to prevent overheating. This protective function is crucial for maintaining the APU's operational safety and longevity.

In this context, though optimizing fuel efficiency and assisting in engine startup processes are essential functions in their own right, they do not directly address the primary safety concern of preventing overtemperature conditions, which is the main role of the load control valve.