Degraded / Jammed Elevator

A degraded or jammed elevator will result in less effective elevator maneuverability in pitch control.

Center of gravity position with a jammed/degraded elevator

The best position for the center of gravity with a degraded/jammed elevator is aft. This can be accomplished by moving the passengers to the rear of the cabin and/or by moving fuel to the outer wing tanks if possible. An aft center of gravity position lessens the need for large pitch-control demands, especially during the approach and landing flare.

Required action for a jammed/degraded elevator

If there is no elevator control (jammed), then the stabilizer trim can be used for pitch control. If the elevator control is reduced (degraded), then it should be assessed if there is still sufficient elevator range available to land safely and used to do so if applicable. If not, then the condition should be regarded as having no elevator control. With a degraded or jammed elevator, several actions can be taken to minimize the need for major pitch changes and/or to improve the handling and management of the aircraft:

1. If possible, move the center of gravity rearward; this will reduce the need for large elevator angles, especially during the landing.
2. Plan a long final approach, and make configuration changes, gear, and flaps earlier than usual to allow more time to sort out the aircraft before the next change has to be made.
3. Restrict the flap angle for landing to reduce the flare demanded.

The effects of a failure/reduction in elevator feels

Artificial feel systems (normally duplicated) are employed on powered controls, especially the elevators. They meet the requirement of progressive feel against control surface deflection at constant speed and against a constant angle at varying speed based on our old friend
1/2 x R x V x V
Whenever the feel on an elevator control is significantly reduced, great care must be exercised in its use. The control must be moved slowly and smoothly over minimum angles to avoid overstressing the control surface structure but enough to maintain the flight path. Overstressing the control surface with a lack of feel is a significant problem, and for this reason, turbulence should be avoided.

What is the best center of gravity position with a reduced or failed elevator feel system?

The best position for the center of gravity with a reduced or failed elevator feel system is forward. This can be accomplished by moving the passengers to the front of the cabin and/or by moving the fuel into forward tanks if possible. This increases the aircraft’s natural longitudinal stability and renders the pitch control less sensitive and feeling heavier, therefore making the aircraft less responsive to small elevator movements. Thus the chances of the pilot overstressing the elevator control surface are minimized, although still possible.

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