APU Speed Droop

[Danial9874]

Hi guys,

B737 APU ECU energize ignition system if APU engine speed goes below 95% during APU operation (speed droop)

What is speed droop ? Tried to google but hardly understand the meaning of speed droop 😔

Thank you

[greatwhitehunter]

It's simply a drop in APU speed. Depending on the cause of the droop the energised ignition sytem might stop an APU shutdown.