How many minutes must electric heat be turned off before and during engine start?

The requirement to turn off electric heat for a minimum of 2 minutes before and during engine start is grounded in the operational and safety protocols established for the King Air 350. This interval is crucial as it allows for several key functions to occur safely.

Firstly, electric heat systems can draw significant power, and having them on during engine start can lead to increased electrical load on the aircraft’s systems. This can be particularly critical when the engines are started since the electrical system is already under strain as the starter motors draw power. By ensuring that the electric heat is off for at least 2 minutes prior, the load is minimized, preventing potential electrical system malfunctions or failures during a critical phase of flight preparation.

Secondly, keeping the electric heat off allows for more efficient engine starts. If the systems are drawing power, it could potentially impact engine performance and ignition reliability. Thus, the 2-minute wait serves to optimize engine start conditions.

This requirement not only enhances the safety of the operation but also ensures the longevity and reliability of the aircraft systems by preventing unnecessary electrical strain during engine starts.