How to survive an engine failure in a single engine aircraft

Transcription

1 How to survive an engine failure in a single engine aircraft Don't Go In Pointed End First There you are 110 kts, 3,000 ft., enjoying being in the air and out of contact with all the folks on the ground; without warning the engine quits. Three things are going to happen immediately, the aircraft is going to slow down, begin to descend and you are going to be one very surprised aviator. It will take you what seems an infinity to figure out what is happening and to do something about it. There are two things you must do immediately, get the nose down to avoid stalling and start looking for somewhere to land. You have about 4 minutes left to touchdown. You have lowered the nose, what do you do next? Pick somewhere to land. Your choices are very limited and will be dependent on both your height and the terrain you are flying over. The key rules are land into wind and don t stall. A good rule of thumb is that if you look down a line from your eye to a point a little bit more than half way along the wing and then to the ground the aircraft can reach any point between you and where the line meets the ground. This is true for all heights. You can reach any place on the ground inside the point where this line touches the ground Page 1 of 5

2 What speed do you glide at give you the best chance of pulling off a successful forced landing? The best gliding speed is usually around 60 kts in a light aircraft and this speed will give you the maximum distance the aircraft will travel before reaching the ground. However, this will be in still air conditions and any wind may have a significant effect on the ground distance you can travel. So what will be the effect of putting the speed up by say 10 kts? The diagram below shows that for maximum distance we want to glide at the speed giving the best Lift/Drag ratio and this speed is where a tangent drawn from the origin meets the drag curve. Drag Drag Best Gliding Speed Increasing the speed slightly over the best gliding speed hardly effects the distance you travel but gives you a bit more energy to play with in the critical final stage of the approach. Flying even a small amount below the best glide speed will however reduce the gliding range particularly into a head wind and could lead to a stall spin in the final stage of the forced landing. The key thing now is to keep your speed 5 to 10 knots above your best gliding speed so as not to turn the engine failure into a stall/spin accident, you will probably survive an arrival with the wings level and the fuselage parallel with the ground but going in pointed end first is usually not survivable The wind. The wind speed will probably be a significant fraction of your landing speed so if possible always land with a headwind, however slight. Only in the most dire of circumstances try to land downwind. So the basic rules for facilitating a successful forced landing following an engine failure are:- 1. Speed slightly above the best gliding speed, up to 10 kts. 2. Don't Stall, Don t Stall, Don t Stall 3. Arrive at the ground with wings level and the fuselage parallel to the ground 4. Don't land downwind. Airspeed "It is better to go into the far fence at taxiing speed than the approach end fence at flying speed." Page 2 of 5

3 Types of Engine Failure Engines can fail in an almost infinite number of ways from a sudden mechanical failure to a more insidious failure due to carburettor icing. A catastrophic failure is in some ways the easiest to deal with in that the aircraft is going to begin descending immediately and there is no possibility of getting power back again. Your decision has been made for you. At the other end of the spectrum a slow build-up of carburettor ice can go un-noticed for some time and a late application of carburettor heat may be insufficient to prevent the engine stopping. Carburettor Icing This is probably the most common cause of Engine Failure. The symptoms are fairly easy to spot in that the engine begins to run rough and you have to increase the throttle setting to maintain airspeed. If this happens there is only one action you can take, FULL CARBURETTOR HEAT. Do not use partial heat as this will in all probability make the icing worse. Catastrophic Engine Failure Although these are very rare they do happen from time to time and are sometimes accompanied by damage to the engine cowls causing a significant increase in drag. A further hazard is that of large amounts of engine oil being blown out of the engine and over the windscreen. If a catastrophic engine failure happens then the aircraft is going to slow down rapidly, there will be a lot of what the hell is happening and a very real danger of the aircraft stalling. Your immediate action must be to get the nose down and avoid stalling. If the engine fails at cruising altitude then you have some time to sort things out and plan your landing. But remember that if there is damage to the engine cowls then the drag and the rate of descent will be significantly higher than you are used to. Engine Failure on Take-off If the engine fails on take-off or in the initial climb getting the nose down and preventing a stall is vital as a stall close to the ground will probably lead to a spin which will reduce your chances of survival considerably. Time is now the problem, you haven t got much before you reach the ground. You really are stuck with landing somewhere in about a 45 degree arc of your heading, and you may have as little as 2 or 3 minutes before you reach the ground. Your only priority is to arrive on the ground in a flat attitude just above the aircraft s stalling speed. You are going to be very busy, if you have time switch off as much as you can and make a quick MAYDAY call. Concentrate on flying the aircraft and don t STALL, if you do you will probably go in pointed end first and join the fatal accident statistics. Turnback following an engine failure on take-off Don t even think about it. Attempting one will most probably kill you. Engine Failure on Approach to Landing If the engine fails on final approach you have only one course of action if you are below about 400 ft. land straight ahead as best you can. Rules 2 and 3 apply, don t STALL and arrive at the ground in a flat attitude, just above the stall speed. Above 400 ft. you have some time to sort the problem out but below this time and your options are very limited and your main effort must be to get the aircraft on the ground in a flat attitude and without stalling. Page 3 of 5

4 Remember the Oh My God, what is happening factor is going to be very high in this situation. That plus the time it takes to find and select a suitable landing area means you will have very little time available to pull off a successful landing. However, two things are paramount, don t try and stretch the glide and don t stall do your best to hit the ground in a flat attitude somewhat above the stalling speed. How to Avoid Going In Pointed End First. Engine failures are rather rare occurrences, but they do happen and are the cause of a number of fatal GA accidents each year. Looking at the accident statistics a major cause of the fatal accidents is the pilot allowed the aircraft to stall at too low an altitude to recover before hitting the ground in a nose down attitude. So how do you, as a private pilot, avoid an engine failure turning into a catastrophe. The answer is actually quite simple, PRACTICE, every 4 to 6 weeks do a practice forced landing All it takes is a quick 15 minute trip with a climb to 1,500 to 2,000 ft. above the airport and then set up for a practice forced landing. Start from a different position each time and remember it is only the last 1,000 ft. that counts. Then remember the Golden Rules:- Fly 10 kts faster than the published best gliding speed. Don t STALL The Author William Lonergan learnt to fly on the Tiger Moth and Harvard and was a flying instructor and commercial pilot flying the Cessna 170, Auster Aiglet Trainer and Tiger Moth in Southland New Zealand. He joined the Royal Air Force and trained on the Piston Provost and Vampire T11 before becoming a QFI on the Jet Provost. After his instructing tour he moved onto the Hunter as a ground attack pilot and apart from a tour on the Gnat flew the Hunter for the remainder of his RAF service. Back in civil life William got into the computer business and over the past few years has been designing and building runway performance computers for a wide range of aircraft from the Boeing 747 to the Beagle Pup. William currently fly s Beagle Pup 150 G-IPUP and is an active member of the Skyhawks formation team. Page 4 of 5

5 Tales from an old and ancient aviator. The author has had 3 engine failures in single engine aircraft. Fortunately I have been able to walk away from each one and only one resulted in some minimal damage to the aircraft. Engine Failure No.1 Cirrus powered Auster J1 The engine stopped at about 50 ft. on final approach to a short grass runway at Wanganui airport in New Zealand. I did not have time to do anything but land straight ahead. The cause Carburettor Icing Engine Failure No.2 Tipsy Nipper I was half way through a stall turn at about 4,000 ft. when the propeller stopped. I tried a restart, but to no avail and I was able to carry out a forced landing at Exeter airport. If I had of attempted more than one restart then I would not been able to reach the airport and would have had to land in a field. I decided that my priority was to land at Exeter rather than attempt more re-starts. The cause I later learned that a stall turn in a Tipsy Nipper often resulted in the engine stopping. Engine Failure No.3 Hunter Mk 6 I was climbing out of RAF Chivenor and as I passed through 25,000 the engine ran down to idling. This was followed by a long what the hell is happening time while I figured out exactly what was happening. I turned towards Chivenor and tried a few things but nothing I did restored the power. Fortunately there was no mechanical damage to the engine and it continued to run at idling so I had full hydraulic pressure to operate the controls, flaps and undercarriage. Chivenor radar set me up for an emergency approach and lined me up with runway 27 for a glide landing. At 4,000 ft. 4 miles from the touchdown point I lowered the undercarriage, pointed the aircraft at the end of the runway. On the day the surface wind was calm but on the last part of the final approach there was a 10 to 12 kt. tail wind and I crossed the threshold at around 200 kts. After some hard braking and a few Bloody Hells I went into the barrier and came to a gentle halt. Going into the barrier caused some minor damage to a control rod cover on the top of the fuselage. The cause Fungus in the fuel control unit becoming dislodged and blocking a vital fuel control valve. What did I learn from these 3 engine failures? They catch you unawares It takes significant time to figure out What the Hell is Happening. You quickly run out of Time and Height. Your full concentration must be on flying the aircraft and landing safely Page 5 of 5