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The Probability of an Engine Failure in a Certified GA SEP

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The Probability of an Engine Failure in a Certified GA SEP

Old 16th Mar 2015, 15:03
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I have had two engine failures (one partial but could not maintain height). Both were due to professionally supplied parts or maintenance. In one case I had told the maintenance organization I thought there was an issue and had wasted significant time and money for no fault found till the other mag failed and I ended up on 1/2 a mag over Scotland (Robin DR400).

That is in around 1200 h, but both issues were in the first 600. I do my own maintenance now

Rod1
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Old 16th Mar 2015, 15:12
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The Chipmunk has 2 fuel pumps, both mechanical diaphragm types, in parallel. Both feed the carburetor simultaneously and one is used to prime the engine as well, using a manual lever.

If the one used for priming fails you'd know because you'd not be able to prime the engine. But if the other one failed you wouldn't know you were relying on just one until the first failed as well (at some point after priming), when the engine would stop!
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Old 16th Mar 2015, 15:19
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Then how do you know you can turn it OFF if you need to?
Because I ripped out all of the fuel lines, replaced the worn gascolator, renewed the selector, and at the 50 hr, and each annual we check it. I also check it once a month. The comment was I leave it on after each flight. Given I am the only one that flies my plane, I am quite happy with it.

Mainly due to this incident

http://www.iasa.com.au/folders/Safet...fueloffed.html
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Old 16th Mar 2015, 18:05
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maxred, thanks! It's your train set so do as you think fit.

Regrettable though that accident was am not sure it proves much in the respect we are discussing. But I would prefer to read the whole accident report rather than a news article summary.

I can see some of the counter arguments to not turning the fuel off but in the training context I still think it should be taught.
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Old 16th Mar 2015, 20:04
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Firefly, I agree that within the training context, all procedures should be taught in line with the POH of type. Generally training types, if such a thing exists, are designed to ensure that the unwary, do not get trapped. Therefore, on, off, on again, training rote, getting the student into the ABC mentality. As you progress though, particularly with older types of aeroplanes, certain idiosyncrasies crop up, often peculiar to model, and individual airframes.
The early Bonanzas, in particular, have some strange and peculiar fuel set ups. Therefore for me, I keep it on selected tank. At least I know the engine was running when I landed
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Old 16th Mar 2015, 21:08
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I've had three engine failures very low after takeoff. One, a fuel interruption, put me back on the remaining runway (I could not have made it past the end ), another, at only a couple of hundred feet was ice crystals in the fuel, into the next field, no damage, and took off later when resolved. The last was the mouse nest of insulation from under the glare shield, being sucked from the air hose, into the venturi, with the application of carb heat, again, into a field, no damage, towed it home.

Very much worse has occurred during testing I was doing, but I was up high, and testing for it - it happened! Consider the tried and true C 180. Owner installs a STOL kit - yippee! Look at those high AoA's and steep departures it can do now (not safely). Then owner installs a larger carburetted engine - still no fuel pumps. Wow, it goes up even better now! But.....

When you combine the higher pitch attitude capability with a STOL kit, with the higher fuel flow demands of a bigger engine, you can get the plane into a very nose high danger corner, in which it will quit, and from which recovery to gliding flight is unlikely. The carb inlet is actually higher than the tank outlet - 15 degrees pitch up is in the danger territory. I agree, this is far away from the regular airport circuit technique, but there are pilots doing, it and I have done the testing to demonstrate that there is a much greater risk of EFATO doing this. Floatplanes are more vulnerable, as pilots are sometimes trying to outclimb terrain. A friend of mine, a very competent, though perhaps a bit complacent, friend of mine broke his back in the resulting crash - and he has heard my admonishments on this (beforehand).

So EFATO's are happily rare, and there are things you can do to make them even less likely. But, flying with "room" for them to happen without ruining your day, is a good idea when you can.
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Old 16th Mar 2015, 21:23
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To give a better idea of why extra speed is better than extra height immediately after take off here is a good example.

We were scooping water on a fire one day when I had an engine start to fail just after lift off from the water it happened just as I reached my start climb speed which was ten knots over the airplanes normal climb speed.

The extra speed gave me the inertia factor to allow me to scratch my nuts while I decided what I was going to do with the beast.

So... once I was sure I was doing the correct thing I first dumped the nine thousand pounds of water and feathered the prop......did the shut down stuff in the check list and flew seventy five miles back to home base....

....fortunately I got it shut down in time to save the engine because it had blown a cylinder and the piston had a big hole in it.
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Old 16th Mar 2015, 21:47
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And of course aircraft engines run at far higher power settings for much longer than a car engine does. At take off it runs at full power from near-cold for quite a long time
But those full power settings are quite frankly derisory. An O360 displaces nearly six litres, yet typically produces 180hp or less. That's just under 33hp/litre. My 1979 Austin Maxi was putting out around 58hp/litre! Anyone who takes off with a "near cold" engine deserves everything they get.

As I said in an earlier thread, I managed almost 1200 hours with a Rotax 447 two stroke, and didn't have it stop once. On two occasions I encountered a reduction in power, due to water in the premix fuel - it wasn't visible separately, but formed a waxy deposit in the filter. I also had a brief run of misfires, which eventually turned out to be a faulty ignition harness. This could have affected any petrol engine. I don't believe this otherwise good record was down to luck, but sensible engine handling and regular maintenance, which I carried out myself.

If I was constantly worrying about things going quiet, I would have packed in long before other circumstances intervened.
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Old 16th Mar 2015, 22:09
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Pram - here's some news for you. Every piston-engined aeroplane, especially air cooled ones, on its first flight of the day takes off with a near-cold engine. It takes a long time at high power for the entire engine, and its oil, to get up to even temperature throughout. You can't achieve that in ground running, especially with an air-cooled engine. Some bits will get very hot and will be under-cooled on the ground, while, other bits will stay relatively cold, so it's bad practice to ground run a cold engine for long periods.

This is why an aeroplane that is grounded for a long time should never be dragged out, engine run, then put away. If you start it up, fly it! If it can't be flown, don't start it up!

Get it into the air once the oil is hot enough, and get the whole engine warmed through without the very hot spots (heads, exhaust valves etc) getting too hot.
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Old 17th Mar 2015, 00:21
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You list five things that can help to reduce the incidence of engine failure.
None of these things eliminate it.
Imagine flying at night or in acutal IMC or, better yet, night actual IMC in a single and hearing the sudden silence, despite your having done everything possible to maintain the engine and fuel supply system in good operating condition.
It happens, and your survival will depensd upon your having thought ahead of what your alternatives might be.
Nobody would like facing a forced landing at night or in bad weather, but the time may come when there isn't a choice.
You can reduce risk through proper maintenance, but you can't eliminate it.
When you rely upon the continued operation of the one powerplant to get you through a bad stretch, you're undertaking an additional risk.
The risk of engine failure can be reduced but not elminated.
The probability of a bad outcome following an engine failure can also be reduced, but only if we recognize the possibility and plan for it.
It's not a matter of if, it's a matter of when if you fly enough hours.
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Old 17th Mar 2015, 00:39
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It's not a matter of if, it's a matter of when if you fly enough hours.
Exactly:

How many here would fly only over the north Atlantic beyond gliding distance of land in a single engine anything?

In other words...every flight would be over water for your whole career.
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Old 17th Mar 2015, 00:51
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Originally Posted by fdcg27
The probability of a bad outcome following an engine failure can also be reduced, but only if we recognize the possibility and plan for it.
It's not a matter of if, it's a matter of when if you fly enough hours.
I totally agree with your statement, but this is a case of "what should be" vs "what is". What "should be" is that pilot induced engine failures are very rare, unfortunately "what is", is the fact that a very large percentage of engine failures reflect the lack of attention to piloting fundamentals.

I see a collective denial of this fact throughout GA and strongly believe the path to better outcomes is not practicing hero turn backs or perfecting your PFL flight paths, it has to start with a industry wide concentration on the importance of the 5 steps

However engine do fail despite the best efforts of the pilot and so risk mitigation procedures should always be applied.

For me that means the following.

For over water flight I try to stay in gliding distance of the shore and always wear a horse show type constant wear life jacket.

For night flight I will only fly multi engine aircraft at night, except that I will fly a single at night but only in the circuit.
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Old 17th Mar 2015, 00:54
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Originally Posted by Chuck Ellsworth
To give a better idea of why extra speed is better than extra height immediately after take off here is a good example.

We were scooping water on a fire one day when I had an engine start to fail just after lift off from the water it happened just as I reached my start climb speed which was ten knots over the airplanes normal climb speed.

.
I am struggling to see how procedures appropriate to a 2 crew mutli engine flying boat with a disposable load have anything to do with EFATO's in SEP's

The extra speed gave me the inertia factor to allow me to scratch my nuts
Oh yah silly me I forgot the point of the post was to make sure nobody forgot about you skygodly powers.
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Old 17th Mar 2015, 01:26
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I am struggling to see how procedures appropriate to a 2 crew mutli engine flying boat with a disposable load have anything to do with EFATO's in SEP's

It is directed at using speed in any airplane BPF.

This bit was meant to point out the extra speed means the inertia gave me more time to make a safe decision in how to react.
The extra speed gave me the inertia factor to allow me to scratch my nuts



Oh yah silly me I forgot the point of the post was to make sure nobody forgot about you skygodly powers.
You seem to have missed my point completely B.P.F.

And personal insults do not improve this discussion.

Last edited by Chuck Ellsworth; 17th Mar 2015 at 02:27.
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Old 17th Mar 2015, 03:15
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IF you are flying at best glide speed in the majority of single engine light planes made by well known manufacturers, please tell me how there isn't enough speed to flare?

Best glide speed should give you the best (farthest) glide in a no wind situation.

And certainly there is enough energy to arrest the descent at the very end of the flight.

Excess speed might reduce the distance of the glide. AND while you may not need the distance, on the other hand you might.

We aren't talking about flying borate bombers, PBYs or anything else. Just little pipers and cessnas and whatever things the british have.
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Old 17th Mar 2015, 03:41
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We aren't talking about flying borate bombers, PBYs or anything else. Just little pipers and cessnas and whatever things the british have.
I am well aware that this is a private pilot forum, however private pilots are quite able to understand the laws of physics and aerodynamics and also understand these laws apply to all aircraft.

But if it it is creating a problem using aircraft other than little Pipers and Cessna's I can probably use them as examples so I don't irritate or confuse people like you Skyhigh.

O.K. ?
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Old 17th Mar 2015, 03:48
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Wink

No response to the point I made about adequate energy to flare at normal best glide speed.
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Old 17th Mar 2015, 03:57
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No response to the point I made about adequate energy to flare at normal best glide speed.
Of course there is adequate energy to flare at normal best glide speed, I don't see anyone stating there isn't.
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Old 17th Mar 2015, 07:45
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Now, now, boys, lets keep the party polite!

It is always entertaining for the rest of us mortals to see the pilot with the highest opinion of his own ability come unstuck.....

So let me lighten this thread with a story about an Engine Failure on Takeoff that completely satisfied all the witnesses.

For the first time EVER, the Chief Flying Instructor's wife agreed to come up with him in the motor glider, a Falke. (She felt safer in an aircraft with an engine!) The craft was preflighted. Taxied to the end of the gliding club runway, engine run up, and takeoff, towards the clubhouse, commenced. At a height of approx. ten feet the engine stopped.

(The equivalent for us as a cable break at low level) The Chief Instructor handled the power failure with superb technique and managed to stop before flying into the clubhouse. His wife climbed down and said she was never going up again, never!

The Chief Instructor was incandescent. "This airplane is unfit to fly! It will have to be grounded immediately until the Engineer has gone over this engine! Somebody could have been hurt!" etc etc etc.
Until another pilot, well experienced with the Falke, asked the question
"Did you check that the fuel was turned on?"

Silence.

Confirmation. The fuel was NOT turned on. (The custom had been that the fuel was normally left turned on...on this occasion a visitor had ended his flight by turning it off.)

The wife of the Chief Instructor, when sitting in the RH seat of the Falke, and being of somewhat ample proportion, made it impossible to verify the position of the fuel cutoff lever.....

I'm not sure whether a formal report was ever made, but we never let him forget it! No names, no pack drill.
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Old 17th Mar 2015, 07:49
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This bit was meant to point out the extra speed means the inertia gave me more time to make a safe decision in how to react.
When I've got a really important decision to make, I scratch my.... head.

IF you are flying at best glide speed in the majority of single engine light planes made by well known manufacturers, please tell me how there isn't enough speed to flare?

Best glide speed should give you the best (farthest) glide in a no wind situation.

And certainly there is enough energy to arrest the descent at the very end of the flight.
Just to be precise, I've quoted the term "maximum" (rather than "best") from a selection of Cessna flight manuals to which I had referred. The intent being that gliding the plane at the speed for maximum glide will take you the farthest per altitude. That may be "best" if you need to make it to shore, but it may be far from the best, if there's a great landing spot right ahead of you, with some obstacles on the way, and a gusty wind. The pilot needs to make an informed decision as to what the "best" glide speed will be for each situation, and aim to be at that or a faster speed when an engine failure would be more critical.

So referring to:

The Cessna Flight Manuals I quickly reviewed (1979 C206, in particular) state a "Maximum" glide speed. It certainly won't be the best for an EFATO! If you attempt a flare and land from an EFATO at 50 feet, at the "maximum" glide speed in the flight manual of 65 knots, you're going to bend the plane. So, Cessna has wisely also provided a speed for EFATO; 80 knots. That's more like it.
A steady glide approach in a C 206 at gross weight at 65 knots will take you a long way (I've done it from 13,000 feet once), but if you enter a flare at that speed, things will happen very fast. So you are arresting a descent "fast", that means a more sudden change in approach angle, so more G, and trading speed for G more. If you get it wrong, there's nothing left at the bottom but a thump. When you look at the flight path, there will be a very small radius to the change from approach angle, to landing path. Small radius + bigger G = greater trade of energy. Or, from a faster glide approach, with a somewhat more steep angle, you have more stored energy, so that radius will be much larger, and the energy required to arrest the descent less, so you'll have less loss of speed, and more time to get it right.

This was taught to me during flying boat forced approach training, where a full stall landing, or worse, dropping it on, is very undesirable. My mentor told me to imagine I was going down a roller coaster, and at the bottom, smoothly pitch up as though to follow the rails - it worked perfectly. If you're a bit fast, just aim short of the intended landing place, and you have lots of control as you slow crossing the fence.

Though I do realize this it not the rotorheads forum, helicopter gliding none the less provides some insight to this. When gliding a helicopter, energy is stored as rotor RPM, up to 110%, more is better = longer to use it up flaring to land, so less rushed, better landing. But the maximum glide distance in a helicopter will be at a lower rotor RPM, because you're not storing energy in the rotor, you're only using it for the minimum lift you need to fly. If you flare from a low rotor RPM, things will happen really fast.

So, to a point, speed is your friend during any forced landing - speed = choice. Speed is easy to get rid of, when you no longer need it (you can slip a Cessna right onto the surface if you need to).

And it's worth remembering that if you really did get the speed wrong for your selected landing spot, you'd rather cross the near fence too fast, and not be able to stop for the far one, than to not make it over the near one, and crash into something at speed, without the opportunity to get the plane on the ground, and slow down for a while.

When it suddenly goes quiet, decisions must be made with little head scratching - 'cause your thinking, planning skill and experience have covered most of the factors.
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