"Real" Engine outs

[mark sicknote]

A friend of mine had the misfortune to loose the engine on the Cessna 152 he was flying. The instructor took over and made a forced landing. Unfortunately the plane overturned and was consumed by fire. Fortunately they both made it out alive albeit with some injuries.

I am constantly reminding myself to assume I will have an engine failure. Not that it is a possibility.

The one thing my friend mentioned was the difference between having a stopped prop and a prop turning at flight idle. He was surprised at how quickly speed bled off and at how much steeper his glide profile needed to be in order to maintain best glide.

Anyone experienced a similar scenario and like to share the details?

Best,

Sicknote

[TotalBeginner]

I would cosider it a bonus if the prop stopped turning after an engine failure (except if you want to re-start). I would imagine the drag to be less from a stationary propeller than a windmilling one. Maybe I'm wrong ?

[BroomstickPilot]

Stationary prop

Yes, TotalBeginner, forgive me but I fear you are wrong. In fact the drag from a stationary prop is much greater than from a windmilling prop.

To provide a simple explanation, a windmilling prop, by revolving, is giving way to the force of the air passing through its blades. The only resistance being from some aerodynamic drag, friction and engine compression (if there is any left depending on what has bust). Each blade is still to some extent behaving like an aerofoil, thus limiting the amount of drag it produces by converting the energy of passing air into circular motion. A stationary prop, by contrast, is resisting passing air totally. Each blade behaving like a large flat plate held out in the slipstream.

One thing that concerns me about the way PFLs are taught is that all too often students are not warned about the very different handling to be expected of an aircraft power off with the prop stationary. This will require a very much steeper angle of descent in order to maintain flying speed. Add to this the fact that stopped prop is something you cannot practice in the air.

Good luck and keep up the flying.

Broomstick.

[DFC]

Drag from a stationary propeller is less than from a windmilling one. Think of the windmilling prop as being a disk creating drag.

The problem with Glide approaches to landing is that they are done to runways / marked strips.

Pilots are (almost exclusively) trained to use runway aspect and such things to deduce the glide performance in terms of getting the aircraft in and also use the runway to judge the flare, hold-off etc etc.

Training at all levels provides no information or guidance in the differences experienced when doing a glide approach to a big grass field with no marked runway and no familiar ques for judgement. Hence why people have problems with real engine failures into open fields.

Regards,

DFC

[will fly for food 06]

Interesting thoughts. I was under the impression that a windmilling prop produced more drag than a stationary one. I thought that a windmilling prop did produce lift but it is now in the wrong direction. A feathered prop is the best solution but most ppl training aircraft dont have this feature.
The main thing is to fly the aircraft. Remember you have more chance of surviving going into the fence at the end of the field on the ground doing 20 knots than stalling in from 100 feet short of the field.

[Put1992]

And wouldn't a windmilling prop increase your chances of an engine restart?

['India-Mike]

Sicknote

For what it's worth, my view is that it's best to be prepared for the worst, ie instant, no-warning fail at low level. That's what happened to me

http://www.aaib.dft.gov.uk/publicati...2a__g_aorw.cfm

I always assumed that I'd see falling oil pressure/rising temperature, and have about 5-10 mins to manage the situation before the engine quit. Didn't happen that way

Oh, stay in practise - even if the PFL exercise might be artificial it's got all the elements to help you when you have the real thing!

[Contacttower]

I've always believed a windmilling prop creates more drag. Certainly the effects of not stopping a prop after an engine failure on a twin can be catastrophic.

A two bladed prop at idle though is still producing a little bit of thrust, so vs. a stopped prop producing no thrust at all will carry the plane a bit further during a PFL.

[will fly for food 06]

When you do a PFL as opposed to an AFL the idling engine will still supply some thrust. This is not the same as a windmilling prop because the engine is no longer supply torque to rotate the prop. It is the force of the relative airflow over the blades that is causing it to rotate.

[micromalc]

engine failure

Hi All,
The above has been some interesting reading, so I thought I'd add my pint of petrol to the fire.
Been flying for many many years and I always practice "forced landings". So.
I would be bimbling around, see a nice field, and on with the carb heat, throttle back, go thru the necessary motions and line up with said field and think "ok I'll get into there" and then continue with my flight. So far so good.
Then, one day it happened, engine stops. Plane sinks like a brick, no big convenient fields, managed to land ok no harm to plane , crew(me) or passenger
(but I'd aged ten years) Conclusion,nice big fields are never around when you need them, so, practice practice practice and work on your skills of side-slipping.

[mark sicknote]

India Mike,

Thanks for that and I agree totally with last sentiment. Job well done my friend and utmost respect.

DFC - I think you are right. My friend was amazed by the difference a broken (and afire-seized) power plant had on the glide capability of the Cessna.

Thank you for your informative posts.

Best,

Sicknote

[mark sicknote]

PS

My respect Micromalc. Hope I never have to replicate your procedure and if I do...hope I do as well as you did.

Guess there really is some real talent in GA circles!

Best - respect - sicknote

[micromalc]

engine out

Thanks for the kind words, but, if memory serves, it was more luck than judgement. Happy flying.....( I still do PFL's)

[SNS3Guppy]

Yes, TotalBeginner, forgive me but I fear you are wrong. In fact the drag from a stationary prop is much greater than from a windmilling prop.

Absolutely incorrect.

A windmilling propeller isn't just a moving propeller. It's a a moving engine, and the engine is absorbing energy from the slipstream rather than imparting it to the airflow through the propeller disc. The drag from a windmilling propeller can be, and often is, greater than a solid plywood disc out there of the same diameter as the propeller arc.

That said, unless you have substantial excess altitude with which to play, attempting to decrease airspeed enough to allow internal engine drag to stop the propeller isn't in your best interests. You'll likely end up wasting time and altitude that's best spend setting up for a forced landing, communicating distress information, etc. In attempting to slow, you increase your rate of descent, and risk a control loss with a preoccupation of stopping the propeller.

In propeller driven aircraft, I've had 40 or 50 engine failures over the years, many of them in radial engine airplanes. I've had ten or so in single engine piston airplanes, and two years ago two engine failures in turbine singles within a three month period.

In the first of the two most recent single engine incidents, (the airplanes were powered with a Garrett TPE-331-11 powerplant), the engine surged between no power and takeoff power rapidly, and the failure occured over a forest fire at about 300' AGL in a heavily wooded area. I was preparing to put the airplane in the trees, but was able to restore power, or partial power, and followed a two land paved road off the mountain to an airport about ten minutes away.

In the second incident, the failure occured at a lower altitude in a canyon (which was also smoked in and on fire), and resulted in a forced landing on the mountainside. It was a different airplane than the first. The propeller did not feather, and continued to rotate until I was on the ground. A turbine bearing seal failure allowed all the engine oil to be lost overboard; the power section of the engine continued to operate normally with normal temperatures, but no torque was available as there was no oil remaining to actuate the propeller.

With respect to a "real" engine failure, you need to be wholly convinced that it's never a matter of if, but when. The time to handle an engine failure isn't when the failure occurs, but long before that. Plan, rehearse, study, prepare for the time it may occur. When you line up on the runway, be prepared for the failure at any point in the takeoff, and know what lies beyond the departure end of the runway. Know your procedures, speeds, and most important of all, know your cockpit blindfolded. Be able to find seat belt releases, fuel shut-offs, door handles, window or canopy releases, and emergency equipment upside down, with your eyes closed, underwater...know how to get out under unusual conditions or circumstances.

Be mentally prepared. Not just with the simple idea that it could happen to you; be spring-loaded to respond because you fully expect a power failure, fire, control problem, etc. A normal, uneventful flight should be a pleasant surprise.

[Mariner9]

A stationary prop creates less drag than a windmilling prop - any qualified Pilot who thinks otherwise needs to revise his forced landing procedures before he/she flies again IMHO

A tale I've related on here before:

I spent ages agonising whether I should try stopping the engine aloft to properly simulate the glide. Eventually I decided I was going to do it, so climbed to 8000' over a local farm strip (where I often do PFL's right down to landing), then idled back down to 7000' to cool the engine a little (Rotax so water cooled but I decided to be gentle as possible) before switching off.

First thing to report was that I had to fly really slowly (almost to the stall) to stop the prop windmilling. Once the prop had stopped however, the decent rate at best glide speed improved (ie decreased) significantly, but was still greater than a normal idle glide. Had great fun gliding around for ~ 5 minutes, experimenting with different speeds to find the optimum glide speed, found it to be more or less what the POH said it should be. Also cycled the wobbly prop, was great for adjusting decent rate without retrimming, could be very useful in a real forced landing.

Finally decided to restart by windmilling - had to dive to 120kts before prop started to turn again, but the engine fired instantly.

Very useful experience IMHO, I now know the true glide characteristics of my aircraft should I ever face an engine failure. No doubt a controversial action though, cue loads of posts.....

[micromalc]

engine out

I agree with the above....be prepared......BUT...let's not get too paranoid,
after all, flying is meant to be fun, and if one is not careful you can end up,
and I quote from a gliding friend of mine, "you guys just fly around worrying about engine failures, where's the fun in that?"Be prepared, be safe, & enjoy!

[Sleeve Wing]

Just like to add my "well done" to 'India-Mike. "Every one you walk away from"...........

Had EFATO with a Tiger Moth and couldn't get over just how quickly the ground came up in the last 100 feet. Unfortunately I was still turning "to avoid" and get a clear landing run - knocked a wheel off ! Anyway we walked out.

As an instructor, and as a result, the points I would like to make are these.

Concentrate on maintaining your gliding speed, no faster, no slower.
It may actually seem too fast but this allows sufficient airspeed for the flair.The temptation will always be to pull the stick back as the ground comes up ; don't do it too early.

Don't worry about a small float; it enables you to roundout and maybe avoid hitting the near hedge/fence.

The other was a tip from an old mate who is exceptionally well known in the flying world.
His advice was " In the event, always have somewhere to go...........even if you've just passed it !" Oh, and look to BOTH sides !

[IO540]

It is quite hard to stop a mechanically sound engine rotating. I have seen it done in a C152; you have to pitch up at about 45 degrees into a deep stall, obviously with the mixture shut right off, and eventually it stops turning.

Not something most pilots are going to do by accident

So, if an engine totally stops in anything resembling normal flight, it is likely to be seized solid and trying to start it is a waste of your time (and a waste of battery capacity). Especially if the stoppage was preceeded by mechanical noises etc.

I am sure the great majority of engine failures where the engine continues to rotate are either a) carb icing or b) lack of fuel. You know what to do about the 1st one, and you should know (despite some dodgy practices being taught in the UK PPL training scene) what to do about the 2nd one

There will always be time windows where an engine failure is going to mean a landing into something which is not a nice field. A fair number of airports are in that category, in addition to mountains, forests, etc. All you can do is minimise those windows. But statistics is hugely in your favour here. I am completely un-bothered about flying straight over the Alps covered by cloud at FL180; it takes well under an hour to cross the whole lot, which is well under 1% of my annual time. That's a very good bet. But then I didn't get my engine assembled by some cowboy.

And for over-water, you carry a life raft.

A stationary prop creates less drag than a windmilling one. And a windmilling VP one creates a lot less drag if you pull the pitch full-coarse.

[Fg Off Max Stout]

Yes, TotalBeginner, forgive me but I fear you are wrong. In fact the drag from a stationary prop is much greater than from a windmilling prop.

Just to back up many of the other responses to this misunderstanding with an illustration:

It takes a lot of force and energy to turn over a non-running engine. Have you ever tried to push start a car? In fact it takes a starter motor about 60 amps at 12v to turn over a decent sized engine - that's a welding current. If a failed aircraft engine is windmilling, the power to keep turning over that engine is coming directly out of your glide performance. A seized or feathered prop will provide less drag.

If the quote above was correct, when helicopters have engine failures, they would put the rotor brake on! Instead they allow the rotor to autorotate to gain minimum rate of descent. Same deal - think about it!

['India-Mike]

Agree wholeheartedly with sleeve about speed control - being trimmed at whatever speed you want to use seriously reduces workload, leaving you with spare capacity for other things. Mainly not getting maxed-out!

I made notes after my failure 2 years ago, and this thread has made me dig them out again. I noted that I remembered looking at the ASI only twice and both times it said 70kt. After the second time I felt I speed wasn't a problem - but that's only because (I assume) I got the thing properly in trim. didn't look at the ASI again.

Also, I forgot to switch off fuel; mags; master. I forgot to tighten my harness; I forgot to jettison the canopy side panels. Caught up in the moment I suppose but could have had nasty consequences if the sand hadn't been firm. Only 50 sec from failure to being on the beach, so things happened quickly. Live and learn