"Real" Engine outs
 

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:ok:

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 ?

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.

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

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.

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

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:bored:

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!

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.

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.

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.

India Mike,

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

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:ok:

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:ok:

engine out
 

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

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.

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:ugh:

A tale I've related on here before:

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!

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 !

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.

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!

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:)

Engine outs
 

I had an instructor who reached out and actually switched the engine off in a 152 at 3000 feet; albeit over a low flying area, and with plenty of warning.
His reasoning was, he wanted me to feel how scary and quiet it was if it ever happened for real.
Very sobering experience.
The same guy had me do a dead stick grass landing beside the runway.
Really puts the pressure on and makes you realise if it happens for real, you'll go down real fast, and you only have one shot...

In Canada, the advice is to pick a touchdown point one third into the field -- halfway if it's a short one.

Clearing the trees and wires on approach is the first priority.

Certainly once the obstacles are definitively cleared, you can steepen the approach to get a longer landing run, but you'll likely be surprised how short the ground run can be in a plowed field;)

From an instructor point of view, I firmly believe in giving realistic training. A student of mine will find a flight that ends without multiple engine failures, no matter what the training environment, to be a shock. A student should never be permitted to have his or her first forced landing off field occur by themself. It should have occured with an instructor on board in the training environment such that the "emergency" has become a familiar event.

That depends very much on the engine and propeller system in use. It's certainly not the case for all engine/propeller combinations. Know the system you're using, but don't apply what you know about one system to another. Know your airplane.

It is the most amazing feeling when there is a sudden silence!! It is rather surreal and then the realization sets in thank God my instructor was so annoying with constant EFATO drill!!!! There is that point when you dont believe its stopped, then you tap the gauges!!! Then you think OMG I have now to put into practice what I have learned!
Done it twice not looking forward to the third one!!!!

I think what people are getting confused with here is a windmilling and an idling prop. In a PFL the prop is idling not windmilling and is producing some, albeit negligible thrust. In an actual engine failure, whether the prop stops or windmills, the drag will be significantly higher than the idling prop in the PFL, hence the glide characteristics will be completely different to what has been practised.

I've never had one yet & not looking forward to it.
There are three scenarios here, a "flight idle" PFL, a "windmilling" fuel/carb ice stoppage & a stopped prop / siezure. I would think the usually taught idle PFL is the least like the real thing, in the first place you are taught to "warm" the engine every 500ft, very useful just when you need a bit of thrust! 2 you are reasonably sure it will go when you need it when you realise the field isn't big enough, 3 you "know!!" the exercise does not involve an actual landing, 4 you knew it was going to happen.
The windmilling prop must produce the most drag, think gyroplanes, how many helicopter pilots have been in autorotation going up? next is the stopped prop/plank, feathered blades may help but I don't have those.
Assured success seems to be more a case of location, location, location.
So, perhaps I should stay in the circuit & practice glide approaches.
Well done everyone who are still able to tell us about theirs.

um, I might be way off in left field here, but anyone who has ever flown a gyrocopter?

Some years ago we were hanging around at our glider field early in the morning, and heard a whistling over the threshold. Turned around to look, and here came a C152 with a stopped prop. Landed down field a little bit, started back up, taxied back, and departed. I remember saying to my club-mate "well there is something you don't see every day."

The glide angle of a stopped engine is steeper than the idling engine. Is anyone really suprised at that fact? The problem with that is in the execution of the procedure for real. The standard PFL pattern doesn't give much lattitude for correction, so when the it's discovered that the angle is steeper in the real case - it's often too late and the pilot ends up in trouble.

I grew up using the military 'Contant Sight Line Angle' (SLA) technique which gives you a lot more lattitude and if your glide angle is steeper, the technique will allow you to identify that fact quickly and correct it with plenty of room to adjust the pattern to compensate. When I trained as a pilot, I already had about 400 hours gliding. The PFL technique I learned is what I had used sucessfully a thousand times or more in gliders. And I have had cause to use the technique twice for real in powered aricraft - both time with complete success.

When I converted my military instructional qualifications into the civilian rating, I was required to teach the PPl technique. I found I couldn't do it! Judging the glide angle was very difficult and I either over or undershot on every attempt. After some scorn from my instructor, I then demonstrated three glide circuits using the constant SLA landing on the numbers each time. I subsequently had to learn the PPl technique, but I will never be convinced that it is better than the SLA technique.

So why isn't the SLA technique tought in the PPL syllabus? This question was being banded around in the 90's when I was an RAF QFI on piston singles. The CAA safety magazine had a discussion for nearly a year regarding this question and some interesting facts emerged. The Statistics showed that military pilots had a forced landing sucess rate of over 90% whereas the civilan sucess rate was less than 50%. This is part due to the mlitary pilots being in better practice, but a lot of it was considered to be due to the SLA technique. There was a move to change the PPL syllabus to the SLA technique, but there is a lot of inertia in the system and it was considered the technique was too complex to learn and would take too many resources. this is slightly ironic as most pilots who have learned it subsequently confess it isn't difficult.

If your club has an ex military QFI, get him to demonstrate it one day.

You betcha. About as much fun as you can have in an aircraft, with your clothes on.

Disregarding the fact that when military pilots experience a problem of a significane enough nature that a civillian pilot would execute a forced landing, the military pilot ejects...

You don't eject from a Grob Tutor, you know! I doubt that statistic included fast jets.

In fact, as far as I know, no-one's ever bailed out from a Tutor, either, even though all operations are carried out wearing parachutes. I'd be interested to know if I'm wrong, because I quote that statistic to cadets regularly!

There was an incident about three years ago when one shed a prop blade, followed by the engine cowlings and canopy before the pilot managed to shut it down, but they still landed that one in a field. (Hairline cracks in the props were found on a number of other Tutors leading to an AD.)

Tim

It is in some places.

There is no specified forced landing procedure for the PPL or the CPL. The requirements in simple terms are to maintain control, ensure safety and make it to a suitable landing area.

The great thing about the SLA is that the basic methods involved can be taught and learned on the ground using a suitable open space and teaching aid.

Looks funny with students walking round arms outstretched dipping down as the walk! One even tried to be smart and make engine noises until I pointed out that this was an engine out procedure. :D :D :D

Regards,

DFC

Dan said "So why isn't the SLA technique tought in the PPL syllabus?" - AFAIK it is taught by everyone at Old Sarum.

HFD

Indeed it is...

Dan, for the uninitiated (myself), please can you explain what the Constant Sight Line Angle is, and how it is used?

Thanks

Yes thanks for that G-string....As far as I can ascertain its simply the angle between an object and the ground below. Don't know how to convert that angle into a practical engine off landing.

Best,

Sicknote:ok:

SLA
 

Isn't this essentially the same technique the military uses for flying the circuit? Instead of flying a square circuit with a well-defined base leg, they fly a continuous curve, starting on downwind abeam the numbers, keeping the angle to the touchdown point (the numbers) constant, and use the wideness of the turn as the adjuster?

The success of a forced landing is based on the sucessful landing of an intact aircraft. Leaving the aircraft as a pile of wreckage in a smoking hole while you descend by parachute could hardly be classed as successful. Besides, the statistics were for light piston singles which don't tend to have ejector seats.

The SLA technique involves you imagining an angle between you and the touchdown point. If that angle is increasing, you are going to land long. Conversely, if that angle in decreasing you will undershoot. This requires you to fly an almost complete curving approach to the touchdown point. it may sound like what you do already, largely because you have worked it out for yourself. But in my experience, it is tought very infrequently at club level. From my experience of teaching it, students picked it up very quickly - and once mastered they made sucessful glide approaches nearly every time. The primary skill is judging the changing SLA. It's not as difficult as it first may seem.

The military oval circuit isn't really flown using the SLA because the aim is to roll out at 300' or so. However, the glide circuit is taught using the SLA and the final roll out can be - and often is quite low.

I have attached the page from the Chipmunk Student Study Guide which shows the SLA PFL pattern. be aware that you don't have to reach Hi Key at the specified heights. Once you are experienced in the technique, you can join the pattern at any point.

http://i210.photobucket.com/albums/b...hippy/1705.jpg

Dan

Thanks for that. I always endeavour to practice PFLs, but I've never seen this technique explained, although I'd heard of it.

From what I've observed, there are a lot of military pilots on this board - conversely, 'their' way of doing things is often documented here. It seems to me that the millitary have a much better 'hands on' approach/style to various aspects of flying, many which seem to be better than the civilian way of doing things.

It would be interesting if a thread could be started that highlighted these differences, (with explanations, of course), perhaps giving both sides the chance to learn from one another?

Looking at the diagram, I get the suspicion that the curving approach is keeping the aim point off the wingtip until turning final.

Dumb Question -- Is the constant angle in the horizontal or vertical plane? I know in gliders we like to maintain a vertical angle to the aim point.

Don't think I'd make friends practising this approach at an active airfield in North America.