Relevant extracts of FAA Advisory Circular 120 - 109 dated 08 Jun 2012, based on the Colgan Air, Air France and other stall related accidents at high and low altitudes.
TABLE 1. STALL RECOVERY TEMPLATE (WITH ASSOCIATED RATIONALE)
Rationale: While maintaining the attitude of the airplane, disconnect the autopilot and autothrottle. Ensure the pitch attitude does not increase when disconnecting the autopilot. This may be very important in out-of-trim situations. Manual control is essential to recovery in all situations. Leaving the autopilot or autothrottle connected may result in inadvertent changes or adjustments that may not be easily recognized or appropriate, especially during high workload situations.
2. a) Nose down pitch control…........................................Apply until stall warning is eliminated
b) Nose down pitch trim…….………………………..….As Needed
Rationale: a) Reducing the angle of attack is crucial for recovery. This will also address autopilot-induced excessive nose up trim.
b) If the control column does not provide sufficient response, pitch trim may be necessary. However, excessive use of pitch trim may aggravate the condition, or may result in loss of control or high structural loads.
3. Bank…………………………………………………..…….Wings Level
Rationale: This orients the lift vector for recovery.
4. Thrust …………………………………………….………….As Needed
Rationale: During a stall recovery, maximum thrust is not always needed. A stall can occur at high thrust or at idle thrust. Therefore, the thrust is to be adjusted accordingly during the recovery. For airplanes with engines installed below the wing, applying maximum thrust may create a strong nose-up pitching moment if airspeed is low. For airplanes with engines mounted above the wings, thrust application creates a helpful pitch-down tendency. For propeller-driven airplanes, thrust application increases the airflow around the wing, assisting in stall recovery.
5. Speed brakes/Spoilers……….…….…………………………..Retract
Rationale: This will improve lift and stall margin.
6. Return to the desired flightpath.
Rationale: Apply gentle action for recovery to avoid secondary stalls then return to desired flightpath.
No comments:
Post a Comment