AFH Chapter 4-21 Elevator Trim Stall

Elevator Trim Stall 

The elevator trim stall demonstration shows what can happen when the pilot applies full power for a go-around without maintaining positive control of the airplane. 

 

This is a demonstration-only maneuver; only flight instructor applicants may be required to perform it on a practical test. 

 

However, all pilots should be familiar with the situations that can cause an elevator trim stall, how to recognize it, and the appropriate recovery action should one occur. 

 

This situation may occur during a go-around procedure from a normal landing approach or a simulated, forced-landing approach, or immediately after a takeoff, with the trim set for a normal landing approach glide at idle power. 

 

The objective of the demonstration is to show the importance of making smooth power applications, overcoming strong trim forces, maintaining positive control of the airplane to hold safe flight attitudes, and using proper and timely trim techniques. 

 

It also develops the pilot’s ability to avoid actions that could result in this stall, to recognize when an elevator trim stall is approaching, and to take prompt and correct action to prevent a full stall condition. 

 

It is imperative to avoid the occurrence of an elevator trim stall during an actual go-around from an approach to landing. 

 

At a safe altitude and after ensuring that the area is clear of other air traffic, the pilot should slowly retard the throttle and extend the landing gear (if the airplane is equipped with retractable gear). 

 

The next step is to extend the flaps to the one-half or full position, close the throttle, and maintain altitude until the airspeed approaches the normal glide speed. 

 

When the normal glide is established, the pilot should trim the airplane nose-up for the normal landing approach glide. 

 

During this simulated final approach glide, the throttle is then advanced smoothly to maximum allowable power, just as it would be adjusted to perform a go-around. 

 

The combined effects of increased propwash over the tail and elevator trim tend to make the nose rise sharply and turn to the left. 

 

With the throttle fully advanced, the pitch attitude increases above the normal climbing attitude. 

 

When it is apparent the airplane is approaching a stall, the pilot must apply sufficient forward elevator pressure to reduce the AOA and eliminate the stall warning before returning the airplane to the normal climbing attitude. 

 

The pilot will need to adjust trim to relieve the heavy control pressures and then complete the normal goaround procedures and return to the desired flightpath. 

 

If taken to the full stall, recovery will require a significant nose-down attitude to reduce the AOA below its critical AOA, along with a corresponding significant loss of altitude.