The engine trim 4 way beeper switch on the pilot's and co-pilot's collective is active only when which mode is selected?

• A. Manual mode of operation
• B. Auto mode
• C. Standby mode
• D. Normal mode

Answer: (C)

In this kind of system, some controls are gated by the mode you’re in so you don’t make risky adjustments during flight. The engine trim 4-way beeper switch is a manual trim control, and it’s designed to be operable only in standby mode.

Standby mode is the state used for checks, calibration, and non-flight setup. Allowing manual trim adjustments there lets you set reference values without affecting in-flight stability. In other modes, trimming is typically automatic or locked out to prevent pilots from unintentionally fighting the system or altering engine behavior mid-flight.

So, the switch being active only in standby mode makes sense because it keeps manual adjustments safe and intentional, away from normal flight operations.