Originally Posted by
funfly
Flying using the trim might be OK if the elevator is jammed but if the cable has broken it is very possible that the elevator would be able to move around offering a quite different scenario.
Hopefully the elevator will be moving. The idea is that the elevator moves in response to the trim tab movement, and this causes the aircraft to pitch up or down.
If the elevator is locked completely solid, then you only have the tiny trim tab moving, instead of the much larger elevator, so the aircraft pitch response response will be very minimal. And, to further complicate your life, the pitch movement will be in the other sense of normal response to trim movement - i.e. if the elevator is completely frozen, trim nose up to cause a very slow pitch down. Note: this is referring to an aircraft with a trim tab on the elevator. It does not apply to aircraft where a moveable stabilizer is used for pitch trim.
The Twin Otter AFM has an Emergency Procedure to cover loss of elevator control, so the pilots would hopefully have some idea what to do.
From the DHC-6-300 AFM:
Elevator Control Malfunction
WARNING
AIRCRAFT LONGITUDINAL RESPONSE TO ELEVATOR TRIM CONTROL AND POWER CHANGES WILL BE REDUCED. AVOID LARGE AND/OR RAPID CHANGES IN TRIM AND POWER.
SECTION 3 EMERGENCY AND ABNORMAL PROCEDURES
TC Approved
If movement of the control column does not produce a corresponding change in pitch attitude, longitudinal control can be managed by using the elevator trim. Engine power should be used to control vertical speed and airspeed.
Flaps should be extended or retracted cautiously, in increments of 5° or less.
Application of power will usually result in a nose-up pitching moment, and reduction of power will usually result in a nose-down pitching moment.
Extension of flap will usually result in a nose-up pitching moment, and retraction of flap will usually result in a nose-down pitching moment.