IVAN'S AVIATION MINUTE-STALLING By Ivan van der Schaar The next manoeuvre I give my students after steep turns would be the power off stall... Once again we are just going to look at flying the manoeuvre and I am not going to go into details technical aspects as this could keep us busy till next month. For the power on stall and accelerated stalls I suggest do them with an instructor who is competent in this field. The reason for this is that aircraft stall characteristics differ vastly from type to type and recovery from these manoeuvres needs thorough understanding because if recovery is executed wrongly a violent spin can develop…. The first thing we are going to do before stalling are the HASELL checks: H - Height: to be able to recover above 2000ft AGL A - Airframe: Review the intended stall with regard to gear and flap settings also review the limitations imposed on these. C of G can also pay a major part but should have been checked during pre-flight S - Security: All seat belts and harnesses tight and no loose objects in the cabin. E - Engine: T's and p's checked, fuel selection and fuel pump on. Engine set for climb. L- Location: Away from built up areas, rising high ground or large expanses of water L - Lookout: This is a 360' turn. The first 270' of the turn is done at 30' angle of bank and the last 90' of the turn is done at 45' angle of bank. This is to ensure the aircraft turns into the inspected area. Initiating the stall Initiate the stall as soon as possible after completing the inspection turn. Make sure wings are level and pick a point on the horizon; this will help you stall straight ahead in a straight line. Ensure everybody is ready by verbal confirmation. If you have Carb heat switch it on. The carb heat should go off at about 20 kts before the stall. Close the power slowly but smoothly to idle. As the speed bleeds of you will have to increase back pressure on the control column to maintain level flight. Get the nose on or above the horizon. Keep it there and the stall attitude will be reached in good time. Maintain wings level with rudder application. The use of ailerons can cause a further wing drop but in the opposite direction and even induce a spin. When the stall warning comes on, treat it exactly like that, a warning. Keep control column coming back. The next thing will be slight buffet on the control column. Don't recover yet. Keep coming back. As soon as she drops her nose or a wing it is time to recover. Stop trimming as the nose goes just above the horizon. Remember the symptoms of the stall. Low wind noise, high nose attitude, controls buffeting controls sloppy and not very effective. The stall recovery Once the positive stall break has taken place, just let go the pressure on the control column. By this time you will have quite a bit of rearward pressure on the controls that by just letting the pressure go will initiate a nose down attitude. Don't push the stick forward as this will cause negative g and become really uncomfortable for man and machine… As the aircraft accelerates and is still in the dive be careful not pull to hard or pluck the controls to get the nose up. This can cause a secondary stall which is usually rather violent and can lead to a wing drop and spin… While you let go the pressure forward push the throttle in at the same time. The throttle movement must be smooth and abrupt. But don't get over eager as this can cause the engine to splutter and take time to come back to life. If a wing was dropped, gently pick it up with rudder as needed. Once the aircraft is stable and speed is increasing, select optimum flap if flap was used. When positive rate of climb is attained, "gear up". Retract the flap on schedule with regards to speed. After the aircraft is "cleaned up", the after take-off checks are done and climb back to your initial altitude. Well folks that pretty much covers the aspects of the power off stall. Please do remember to check your type specific aircraft manual for limitations or special instructions on stalling your particular type. Keep it safe and keep it flying till next month Ivan

Ivan's Aviation Minute

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