The pilot, who was also the owner of the aircraft, took off from runway 29 at Wonderboom on a private acceptance flight following maintenance. The flight was conducted under visual meteorological conditions (VMC). Shortly after rotation, he experienced an engine failure and conducted a forced landing on an open area of veld on the extended centreline of runway 29. After touching down at speed, he realised that he was heading for trees, a concrete structure and telephone wires at the far edge of the open area. Unable to stop in time, he pulled up the nose of the aircraft and managed to clear the obstacles. He then struck the ground heavily. The nose wheel collapsed and the aircraft swung 90° before coming to a standstill. Damage was caused to the propeller, nose wheel and wings. The pilot did not sustain any injuries.

Jim Davis

HISTORY OF FLIGHT

THE PILOT STATED THAT BEFORE TAKEOFF he had completed all his engine and pre-flight checks and had selected the right-hand fuel tank. The engine had performed normally during the checks. On rotation, the engine failed. The pilot changed the fuel tank selector to the left tank but this made no difference. He selected a 40° flap setting and carried out a forced landing on an open area of veld on the extended centreline of runway 29.The pilot transmitted a mayday call to Wonderboom tower on frequency 120,6 MHz.

The accident sequence occurred along the extended centre line of runway 29. The first contact point with the ground was 450m beyond the end of runway 29and the final impact point was 740m beyond the end of the runway. The aircraft came to rest on its nose after the nose wheel collapsed. At the time of impact, the landing gear had been lowered and the flaps selected at 40°.Directly after the accident, while the aircraft was in a nose-down attitude, the fuel gauge indicated that the left tank held six gallons and the right was empty.

Once the aircraft was recovered and placed in a level attitude, the same gauge showed that the left tank held nine gallons and the right, eight. The airframe and engine fuel systems were inspected. No components were damaged and no abnormalities were found. No parts were replaced before the next phase – the engine test runs. The aircraft was secured in a level attitude. The engine was started and then operated at all power settings. No difficulties or abnormalities were recorded. The aeroplane was again secured in the takeoff attitude and the engine tested once more. No abnormalities were recorded.

Bad design. The fuel selector is easy to inadvertently switch off.

During both ground runs, the fuel tank selector was switched from the left to the right tank without the engine misfiring or quitting. Only when OFF was selected did the engine stop. The pilot stated that he had taken off with the right hand fuel tank selected, and when the engine failure occurred, had selected the left-hand tank.  However, during the investigation immediately after the accident, the right-hand tank was found to be selected. The left-hand tank was selected for the engine test after the accident. During the interview with the pilot on the day after the accident, the position of the fuel tank selector valve was discussed. The pilot then became unsure if the original selection had been the left or right tank. He said that he had been trying to rectify the engine problem and fly the aircraft simultaneously and could not recall his actions precisely. He added that he had had no time to switch the electrical fuel pump to HIGH.

Fuel is stored in two main integral wing tanks, each holding 60 usable gallons and one unusable gallon. The fuel is gravity-fed to a collector tank located at the root of each wing. Reverse fuel flow from the collector tank to the main tank is prevented by two flapper check valves in each collector tank. Each collector tank has a submerged, electric centrifugal pump for vapour suppression at altitude. It may be used during normal engine operation both on the ground and in the air when selected in the LOW position. An engine-driven fuel pump caters for normal fuel supply. When failure of the engine or engine-driven fuel pump is expected, the electric pump is used in the HIGH position to supply adequate fuel pressure.

The fuel gauges are like almost all light aircraft fuel gauges – not to be relied upon – and change with attitude

PROBABLE CAUSE

Although the cause of the engine failure could not be determined, fuel mismanagement (moving the fuel selector to the OFF position) at the moment the emergency occurred, could not be ruled out.

The complex Malibu fuel system.

JIM’S COMMENTS

Bear with me for a moment. I grew up on a farm in Kenya in the days when all machinery was unreliable. We had a D2 Caterpillar tractor that used a 600cc pilot engine to start the main diesel. There was also a WW2 Willys Jeep and a Studebaker Commander. The second tractor was a tall green1935 John Deere with a 5,2 litre twin-cylinder paraffin engine. It had spiked iron wheels and an external flywheel. Finally, there was a little James motorcycle with a 125cc Villiers engine. All these vehicles had something in common – they broke down from time to time, and the cause was always one of two things:

  • no fuel
  • or no spark

Pretty much all engines are the same. If there is no sudden bang and broken bits, then the problem is either fuel or ignition. Aeroplane engines make diagnosis a bit simpler by having the added safety of two magnetos. So this boils down to an almost infallible rule – if it suddenly stops – it’s a fuel problem.

It was understood that old equipment was likely to break down.

With this insight we can use Ocham’s razor and cutaway all the crap about which tank he thought he selected and which one he changed to. I don’t know what happened – but I am almost certain the pilot switched the fuel off. Sounds silly, but that’s the only way the investigators could duplicate the engine stoppage. And just to be clear, if the pilot caused it, it was an engine stoppage – not an engine failure.

In the pilot’s defence, I have to say the Malibu fuel selector is the stupidest thing I have ever seen. If you are on the left tank, but mistakenly think you are on the right hand tank – which way will you move the lever? And what’s going to happen? Let’s suppose this guy made a habit of never switching the fuel off – a habit which I think has a lot of merit. And let’s suppose the AMO did switch the fuel off.

Now, if the pilot was a conscientiousness type he may well have chosen to start up and taxi on the lowest right tank – the right hand one, and then moved the lever to the left for the run-up and takeoff. But, because he knew his aircraft well (he had 560hours on type) he didn’t look down at the selector –he just moved it to the right or left until it stopped. So from the initial Off position he moves it to the right– thinking he has the right tank, but actually he has selected the left tank. Then before takeoff he moves it to the left – thinking he has selected the left tank, but he has actually switched the fuel OFF.

I can’t be sure this happened – but this is my best guess. When the engine stops at very low level he suddenly has a handful and rather loses his cool. He seems to communicate (calls mayday) then aviate (maintains plenty of airspeed) and then navigate (points the nose at a field that’s far too close).While this is happening he fiddles with the selector, but it’s too late.

And, if he was well trained, he would have closed the throttle. Some will ask why close the throttle if the engine has already stopped? The answer is that you really don’t want to get set up for your field, and then the power suddenly comes back for ten seconds and carries you somewhere you don’t want to be before stopping again. If you close the throttle you know where you stand – you are flying a glider. This guy must have touched down at a hell a speed because he was able to pull her off again, fly over a ‘concrete structure’, some telephone wires and some trees and finally land nearly 1000 feet further on. My guess is that after the dust settled he saw he had switched the fuel off, so he selected the right hand tank to make himself look better to the investigators.

The accident sequence.

Finally, there is something strange going on.

The report says ‘… he had no time to switch the electrical fuel pump to HIGH.’ I don’t understand this comment. The Malibu has the same fuel injected Continental as most Bonanzas, Barons and Cessna210s, all of which give dire warnings in their POHs about switching the pump to HIGH. Indeed I did an accident report a recently about two guys who lost their lives by doing exactly this in a Bonnie at Kimberley. So CAA’s comment makes no sense. We will never know exactly what happened – but there is still much to be learned from this accident.

WHAT CAN WE LEARN?

When you move a fuel selector you are playing with your life – so take the trouble to look at what you are doing. Note for Cherokee instructors. When a pupe changes tanks, always haul their leg away so you can see what they have done. Find out how long your engine will keep running with the selector OFF. Try it on the ground to get an idea how long you can idle and taxi with the fuel switched off. I would also try it in the air at takeoff power. Do it at a sensible altitude over the airfield.

If you are uncomfortable inducing an engine stoppage in the air, then try it on the ground against the chocks. It’s part of knowing your aircraft. Always expect an EFATO and brief yourself for it– out loud. We react positively to instructions that we hear – even if we are the ones giving those instructions. If you are solo then it’s no problem, and if you have pax you simply tell them what you will do in the event of an EFATO, and brief them to unlatch the door on touch down.

I like the Air Force checks: Speed, Field, Fuel, Flaps.

Speed – lower the nose to maintain flying speed (that’s the Aviate bit).

Field – select the best available (that’s the Navigate part). This business of 30degrees either side is plain stupid. If you are ten feet up you won’t make a 30 degree turn, and if you are at 400 feet why limit yourself to a 30 degree turn?.

Fuel – this is the most common problem, so change tanks and use the electric pump – but NOT in the HI position on those injected Continentals.

Flaps – use as necessary to get into your field at the slowest speed. Remember, if you touch down at 45kts you will do only ¼ of the damage that you would at 90kts.Mayday. Only if you have time. It will alert the rescue crew if no one has seen you crashing. This pilot was very compressed for time. I suggest he may have stuffed up the landing because he was concentrating on his call instead of flying the aircraft. Close the throttle when you have an engine stoppage. This applies to both high altitude and an EFATO. At altitude you have time to look for the fault and then try the throttle, but near the ground you don’t have time for that, so just close the throttle.

SUMMARY

  • Be very careful when changing tanks.
  • Learn all you can about your fuel system.
  • Expect an engine failure on every takeoff, and brief for it.
  • Aviate Navigate Communicate. (Speed, Field, Fuel, Flaps).
  • Close the throttle if the engine stops.
  • Mayday is your last priority.

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