Monday, February 16, 2009

Elevator Trim Stall

The elevator trim stall maneuver shows what can happen when full power is applied for a go-around and
positive control of the airplane is not maintained.
Elevator trim stall.
Such a situation may occur during a
go-around procedure from a normal landing approach

or a simulated forced landing approach, or
immediately after a takeoff. The objective of the
demonstration is to show the importance of making
smooth power applications, overcoming strong trim
forces and maintaining positive control of the airplane
to hold safe flight attitudes, and using proper and
timely trim techniques.

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 retractable
gear). One-half to full flaps should be lowered, the
throttle closed, and altitude maintained until the
airspeed approaches the normal glide speed. When the
normal glide is established, the airplane should be
trimmed for the glide just as would be done during a
landing approach (nose-up trim).

During this simulated final approach glide, the throttle
is then advanced smoothly to maximum allowable
power as would be done in a go-around procedure. The
combined forces of thrust, torque, and back-elevator
trim will tend to make the nose rise sharply and turn to
the left.

When the throttle is fully advanced and the pitch
attitude increases above the normal climbing attitude
and it is apparent that a stall is approaching, adequate
forward pressure must be applied to return the airplane
to the normal climbing attitude. While holding the
airplane in this attitude, the trim should then be
adjusted to relieve the heavy control pressures and the
normal go-around and level-off procedures completed.

The pilot should recognize when a stall is approaching,
and take prompt action to prevent a completely stalled
condition. It is imperative that a stall not occur during
an actual go-around from a landing approach.

Common errors in the performance of intentional stalls

  • Failure to adequately clear the area.

  • Inability to recognize an approaching stall
    condition through feel for the airplane.

  • Premature recovery.

  • Over-reliance on the airspeed indicator while
    excluding other cues.

  • Inadequate scanning resulting in an unintentional
    wing-low condition during entry.

  • Excessive back-elevator pressure resulting in an
    exaggerated nose-up attitude during entry.

  • Inadequate rudder control.

  • Inadvertent secondary stall during recovery.

  • Failure to maintain a constant bank angle during
    turning stalls.

  • Excessive forward-elevator pressure during
    recovery resulting in negative load on the wings.

  • Excessive airspeed buildup during recovery.

  • Failure to take timely action to prevent a full stall
    during the conduct of imminent stalls.

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