What is the purpose of a door-to-gear interlock switch?

• A. To confirm doors are properly closed before gear can retract and to confirm door position is consistent with gear movement.
• B. To indicate when doors are jammed during landing.
• C. To measure door temperature during operation.
• D. To control gear lighting.

Answer: (A)

Door-to-gear interlock switches enforce safe sequencing by validating door status before the gear moves. The idea is to confirm the doors are fully closed and that their position is in line with the gear’s movement, so the retract command can only proceed when everything is in the correct state. In practice, the control system uses a door-closed signal and a door-position sensor; if both indicate proper closure, the gear retracts. If the doors aren’t closed or aren’t aligned, the retraction is halted to prevent damage or misalignment. The other options describe functions that aren’t about safe gear retraction sequencing—jam indication, door temperature monitoring, or lighting control.