Will the APU starter engage before the FLAP OPEN annunciation appears on the ECAM APU page?

Will the APU starter engage before the FLAP OPEN annunciation appears on the ECAM APU page?

• A. No
• B. Yes
• C. Sometimes
• D. Not specified

Answer: (A)

The APU start sequence is protected by interlocks with the flap system. The ECAM APU page not only shows the APU status but also uses flap status as a gate for starting. The FLAP OPEN annunciation signals that the flap system has reached a safe state, and only after that confirmation does the APU start circuit become allowed to engage. So, in normal operation the APU starter will not engage before you see the FLAP OPEN annunciation. This is why the correct choice is that the starter will not engage prior to that annunciation. If the starter were to engage before the annunciation, that would indicate a fault in the interlock logic.

The APU start sequence is protected by interlocks with the flap system. The ECAM APU page not only shows the APU status but also uses flap status as a gate for starting. The FLAP OPEN annunciation signals that the flap system has reached a safe state, and only after that confirmation does the APU start circuit become allowed to engage. So, in normal operation the APU starter will not engage before you see the FLAP OPEN annunciation. This is why the correct choice is that the starter will not engage prior to that annunciation. If the starter were to engage before the annunciation, that would indicate a fault in the interlock logic.