What triggers a FADEC to abort an engine start?

A FADEC (Full Authority Digital Engine Control) aborts an engine start primarily due to conditions that may indicate an abnormal or unsafe situation during the starting sequence. A hot start occurs when the temperature exceeds pre-defined limits during the starting process, which can potentially damage the engine if not addressed immediately. Similarly, a hung start happens when the engine fails to produce the expected thrust and does not accelerate properly, potentially leading to a dangerous situation.

In both cases, the FADEC monitors critical parameters such as exhaust gas temperature (EGT) and engine speed during startup. If it detects either a hot start or a hung start condition, it activates the abort sequence to prevent engine damage and ensure safety. This automatic response is part of the FADEC's design to maintain optimal engine performance and safeguard against any risks associated with starting the engine under unsafe conditions.