Power off Stall Procedure

 

The objective:

To develop the pilot's ability to recognize an approaching stall by sound, sight, and feel; familiarize the pilot with the conditions that produce power-off stalls; and to develop the habit of taking prompt preventative or corrective action to recover from a stall

Elements:

1.     Aerodynamics of power-off stalls.

2.     Relationship of various factors such as landing gear and flap configuration, weight, center of gravity, load

3.     factor, and bank angle to stall speed.

4.     Flight situations where unintentional power-off stalls may occur.

5.     Recognition of the first indications of power-off stalls.

6.     Performance of power-off stalls in descending flight (straight or turning).

7.     Entry technique and minimum entry altitude.

8.     Coordination of flight controls.

9.   Recovery technique and minimum recovery altitude

The Completion Standard:

1.  Exhibits knowledge of the elements related to power-off stalls

2.  Selects an entry altitude that allows the task to be completed no lower than 1,500 feet AGL

3.  Establishes a stabilized descent in the approach or landing configuration, as specified by the examiner

4.  Transitions smoothly from the approach or landing attitude to a pitch attitude that will induce a stall

5.  Maintains a specified heading, ±10°, in straight flight; maintains a specified angle of bank not to exceed 20°, ±10°; in turning flight, while inducing the stall

6.  Recognizes and recovers promptly after the stall occurs by simultaneously reducing the angle of attack, increasing power to maximum allowable, and leveling the wings to return to a straight-and-level flight attitude with a minimum loss of altitude appropriate for the airplane

7.  Retracts the flaps to the recommended setting; retracts the landing gear, if retractable, after a positive rate of climb is established

8.  Accelerates to VX or VY before final flap retraction; returns to alt, hdg and asi specified by the examiner

Common Errors:

1.     Failure to adequately clear the area.

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

3.     Premature recovery.

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

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

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

7.     Inadequate rudder control.

8.     Inadvertent secondary stall during recovery.

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

10.  Excessive forward-elevator pressure during recovery resulting in negative load on the winds.

11.  Excessive airspeed buildup during recovery.

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

Power-Off Stall Technique (Landing Configuration):

DESCRIPTION: ·       Select an altitude to allow recovery above 1500’ AGL. ·       Perform Pre-Maneuver Checklist. ·       Perform clearing turns. ·       Apply carburetor heat, as appropriate. Reduce power to 1500 RPM (or 15” MP). ·       Smoothly increase pitch to maintain altitude while slowing to final approach speed. When airspeed is within flap operating range, add flaps incrementally until full flaps are obtained. When airspeed is below Vlo, extend the landing gear as required. ·       Stabilize aircraft, maintaining heading. ·       Adjust power to the approach power setting while establishing the approach attitude.   From final approach airspeed and attitude, reduce power to idle. Continue to increase pitch. Establish a bank angle up to 20o, if desired, in appropriate direction. Initiate recovery when: ·       Imminent stall: The first buffet or rapid decay of control effectiveness is experienced. ·       Full stall: A sudden loss of control effectiveness occurs, excessive sink rate, or sudden nose pitch down with full up elevator is experienced. Recover by simultaneously adding full power (carburetor heat off as required), decreasing the angle of attack, and leveling the wings. Select the second flap setting, establish a pitch attitude to minimize altitude loss (approximately Vx attitude) and establish a positive rate of climb. ·       With a positive rate of climb, select the first flap setting, retract the landing gear as required, and establish Vy attitude. ·       Above the appropriate indicated airspeed, retract flaps. Resume normal cruise, or as specified.

Power-Off Stall Narrative (Landing Configuration):

FULL STALLS POWER-OFF ·       The practice of power-off stalls is usually performed with normal landing approach conditions in simulation of an accidental stall occurring during landing approaches. ·       Airplanes equipped with flaps and/or retractable landing gear should be in the landing configuration. ·       Airspeed in excess of the normal approach speed should not be carried into a stall entry since it could result in an abnormally nose-high attitude. ·       Before executing these practice stalls, the pilot must be sure the area is clear of other air traffic. ·       After extending the landing gear, applying carburetor heat (if applicable), and retarding the throttle to idle (or normal approach power), the airplane should be held at a constant altitude in level flight until the airspeed decelerates to that of a normal approach. ·       The airplane should then be smoothly nosed down into the normal approach attitude to maintain that airspeed. Wing flaps should be extended and pitch attitude adjusted to maintain the airspeed. ·       When the approach attitude and airspeed have stabilized, the airplane’s nose should be smoothly raised to an attitude that will induce a stall. ·       Directional control should be maintained with the rudder, the wings held level by use of the ailerons, and a constant pitch attitude maintained with the elevator until the stall occurs. ·       The stall will be recognized by clues, such as full up-elevator, high descent rate, uncontrollable nose down pitching, and possible buffeting. ·       Recovering from the stall should be accomplished by reducing the angle of attack, releasing back-elevator pressure, and advancing the throttle to maximum allowable power. ·       Right rudder pressure is necessary to overcome the engine torque effects as power is advanced and the nose is being lowered. ·       The nose should be lowered as necessary to regain flying speed and returned to straight-and-level flight attitude. After establishing a positive rate of climb, the flaps and landing gear are retracted, as necessary, and when in level flight, the throttle should be returned to cruise power setting. ·       After recovery is complete, a climb or go-around procedure should be initiated, as the situation dictates, to assure a minimum loss of altitude. Recovery from power-off stalls should also be practiced from shallow banked turns to simulate an inadvertent stall during a turn from base leg to final approach. ·       During the practice of these stalls, care should be taken that the turn continues at a uniform rate until the complete stall occurs. ·       If the power-off turn is not properly coordinated while approaching the stall, wallowing may result when the stall occurs. ·       If the airplane is in a slip, the outer wing may stall first and whip downward abruptly. ·       This does not affect the recovery procedure in any way; the angle of attack must be reduced, the heading maintained, and the wings leveled by coordinated use of the controls. ·       In the practice of turning stalls, no attempt should be made to stall the airplane on a predetermined heading. However, to simulate a turn from base to final approach, the stall normally should be made to occur within a heading change of approximately 90°. ·       After the stall occurs, the recovery should be made straight ahead with minimum loss of altitude, and ·       accomplished in accordance with the recovery procedure discussed earlier. ·       Recoveries from power-off stalls should be accomplished both with, and without, the addition of power, and may be initiated either just after the stall occurs, or after the nose has pitched down through the level flight attitude.