Multi-engine training mixture cuts

[Centaurus]

Am up-dating my briefing notes on multi-engine (piston) asymmetric training after re-reading the CAAP 5.23-1(0) - which covers the syllabus of ME training-day and night. Would appreciate feed-back from instructors who simulate engine failure on take off by cutting the mixture rather than closing the throttle.

Have you struck any handling errors with this technique (student identifying wrong engine, slow to react to swing, time delay after mixture cut to re-introduction of mixture and zero thrust throttle setting during climb out etc). In general what altitudes and speeds do you initiate the mixture cut?

Also is there value in cutting a mixture at rotation with the training intention of teaching the student to immediately land on remaining runway length? Appreciate real experience anecdotes on the subject of simulated engine failures on take off in light piston twins as all instructors can learn from others experiences.

[GA Driver]

Hi centaurus, I thought you'd covered this one before. . .

Anyway, yes I use mixture cuts after takeoff successfully, but I have encountered a few 'problems' from time to time. I've found particularly with a green students (Fresh PPL and initial multi) that there is still the tendancy to 'look inside' for the problem/anecdote rather than look outside and see whats going on and correct it.

With regards to altitudes and time delays, I have my own limits in place and if the person hasn't recovered the yaw or reacted to the engine failure by my limits then it's "Taking over" and I recover the aircraft and discuss what (or what didn't) happen.

I have had the wrong rudder put in on a few occasions, I found if I got the student to remove the 'dead leg' from the rudder pedal altogether, it tended to minimise the confusion. But it does depend on the person.

I've never cut the mixture on rotation and the reason in my madness is because I believe the controlabilty (nose wheel wise) on most twin trainers out there is fairly questionable close to rotation speeds. I emphasise trainers because I've found these to be the worst. This coupled with a slow reaction time could end up rather nasty.

My two cents. . .

GA Driver

[flyby_kiwi]

Have had done to me in the past as a multi student:

The mixture cut on the take off roll just prior to rotation - all OK though I assume the instructors feet wernt too far away had I miss-identified.

Havnt had the engine failure ON rotaion requiring me to reland (wouldnt be enough runway I dont think anyway), usually the instructor would wait till a couple of hundred feet AGL. Fortunatley rotate speed was almost the same as Blue Line anyway.

As an initial multi student I found that as long as I paused ever so briefly to identify the yaw it wasnt difficult to correctly identify the engine - where I found I had to be more switched on was with an engine being failed on the turn onto base or final with a low power setting AND partway through a turn.

[Centaurus]

Thanks so far. Would appreciate any discernable difference in mixture cuts on take off between fuel injected types and normal carby types - specifically in how quickly the engine picks up once the mixture is re-introduced.

[Col. Walter E. Kurtz]

I would suggest that it would be more prudent to fail engines AT ALTITUDE with the mixture, and any failures in the circuit after takeoff be limited to using the throttle. Initially, the candidate pilot should also be told what engine is to be failed and how the engine is to be failed. There should be no doubt or misconception as to what is about to occur.

After some proficiency is attained in handling the failure and proper identification & recovery technique is demonststrated by them, then a few 'trick' failures where the candidate doesn't know in advance which engine is acceptable and is going to be less risky.

The aim is to transfer knowledge - not to play smart@rse instructor who can trick the student - and in the process,increase the risk in having a 'training accident'.

Engine failures after take off should be limited to at least 300 feet agl.

There is no extra benefit to be gained by failing engines at low level after takeoff. The candidate pilot will get as much benefit with failures at or ablove 300 feet agl and having to clamber up to circuit height as is by doing so from a lower altitude, and the risk involved is reduced considerably. There is more margin for error should the excercise go pear shaped in the process.

The aim is to minimise risk involved in engine failure demonstration and practice.

Don't be misled by plenty of bravado that may be displayed by some regarding this subject.

Risk management and reduction is the key to safe training practices.

Don't just take my word for it; call up old timers like Ken Andrews and Ces Sly in Sydney who have been doing twin training for decades and see what their opinion on low level engine failures are, as well as any other advice you can get from these guys' experience.

Here endeth the sermon.

[Menen]

Cor - memories! Old Chew Chew Andrews was one of my instructors on Wirraways a million years ago at Central Flying School on the instructors course. Nice man with a bristling moustache. And Cec Sly and self were RAAF instructors at Uranquinty also a million years ago. He was a very popular chap. How about that -amazing what Pprune comes up with at times.

[Ang737]

I recall back when I was doing ME training with Centaurus himself that engine failures where initially done at altitude with a mixture cut. I consider this a better option than at low levels as it allowed me to concentrate the drill of identifying and securing the dead engine without the added pressure of height at this early stage in training.

As i recall most of the ME drills were performed at altitude including go arounds. I can see the perspective from an instructors viewpoint as to why higher altitude assymetric training is beneficial in that if the green student was to apply the wrong rudder to counteract yaw and one wasn't ready they could easily end up inverted in no time and at low level... well you know the results.

As far as mixture cut compared to throttle, I have only ever seen instructors including during my CIR test that the mixture has been cut with a loud an audible "SIMULATED ENGINE FAILURE" to ease confusion. It gets back to classic human factors that if a student doesn't hear the word simulated and the expectation is just that then confusion can easily set in.

Thats me two cents worth...

Ang

;)

[Onan the Clumsy]

With respect to those more experienced than me, and acknowledging the difference between primary students and line pilots...I can't believe you would consider cutting an engine right at or after take off. On the roll perhaps and maybe just maybe at/after takoff by a power reduction (and with a complete briefing), but not by pulling the mixture.

Have there been any studies into accidents or fatalities during training verses in real operations? I'd say it created an unecessary risk that wasn't worth the potential benefit...and I'd hate to have to tell someone that I'd hurt their family member in a situation of my making.

[Farknel]

Well done with regard to your sound, safe and sane words of wisdom regarding ME training - I wish more instructors understood the ideas of risk management and the fact that they are there to train someone - not trick them.

Fark.

[Winstun]

:rolleyes: Suggest these "fuel mixture cutters" consult their pilot operating handbook on correct way to simulate engine failures....retarding the throttle ......more Aussie know-how sprouting.....:rolleyes:

[bush mechanics]

Maybe thats why alot of owners of the larger twins dont like people doing m/e endorsments in there a/c,I know i wouldnt like someone pulling the mixture on my 60,grand engine.My instructer briefed me before the exercise and said he would be closing the throttle to simulate the eng failure.I think if you are training thats what you should be doing.If a student lost control the instructer only has to advance the throttle, not advance the mixture reach across and hit the boost pumps bit of throttle get it going!!!!Well I guess thats what I think.

[B787]

Some very good info here. Cheers Col, well put.

I tend to use the mixture to simulate the engine failure. I find it gives a much more realistic result. The engine does not tend to stop unless you feather the prop. As the student brings the pitch back to simulate feathering, advance the mixture.

I also use the mixture control in singles to simulate the failure as it makes the student use all the correct techniques. If you close the throttle to simulate the engine failure, the student most times does not include moving the throttle to idle in their checks, as it is already there.

And I never fail an engine below 300 agl. My life is worth to much. Leave that for the sim. You can crash that as much as you like.

[Winstun]

I tend to use the mixture to simulate the engine failure. :rolleyes: Not in accordance with the airplane pilot operating handbook or engine manufacturers instructions of course The engine does not tend to stop ... :hmm: These heroes ought to have their tickets pulled before they kill a student....let alone get their grubby hands on a real plane full of good pax...:{

[flyby_kiwi]

Having not taught multi conversion I have never considered what the a/c manual says about simulating engine failures (twins).

From what Ive seen tho, I havnt seen how retarding the throttle would be significantly safer than the mixture. Once the mixture is reintroduced power is instantaneous without requiring the fuel pumps. Ultimately if full power is suddenly required during the simultation all that need to be done is to advance the mixture back to full rich and your away. Im sure these methods would vary depending on a/c type.

The engine never grinds to a halt as if your at a good IAS (usually blue line) the falied engine will continue to windmill and cutting the mixture seems to result in less 'snap crackle pop' by the engine (in my own opinion). Wouldnt do it in a single myself tho.

Well thats how Ive always seen it and its how the flight examiners do it over here anyway.

[Big Kahuna]

oops

[Menen]

Centaurus. You asked about mixture cut on fuel injected engines. Recall an instructor that pulled the mixture on a Seneca type and got the student to fly a full asymmetric circuit with mixture cut in order to simulate a windmilling prop. It's called double jeopardy.

Student told to do a touch and go while the instructor brought the mixture to rich on touch-down. Student advanced both throttles but due lack of fuel in the lines after several minutes of windmilling at altitude, the engine did not deliver immediate power.

Aircraft swung off the strip during the touch and go and hit an obstruction off the flight strip and ground looped and burnt. Student got badly scorched while exiting aircraft. It is true that mixture cuts can make a simulated engine failure more "realistic" - but there is a limit to that sort of thing. Some call it "practicing bleeding". Very apt description.

And by the way. Seems awfully risky to actually get the student to pull back the pitch lever towards feather as a "touch drill"

Must say that some people really do love taking risks in the name of "training". What's that adage about "there are old pilots and there are bold pilots, but not many old, bold pilots". I'll go along with that.:rolleyes:

[bush mechanics]

When doing engine cuts with throttle your valve train is still getting lubrication from the lead in the fuel,when its windmilling at idle cutoff theres no fuel going to the cylinders,So no lubrication to the valve stems.

[Menen]

Gottom 2 Dollar. Not being an LAME I don't know the ramifications of loss of oil to valve stems. Does this mean mixture cuts can cause severe engine damage long term? If so, why has not CASA issued a warning on this type of engine failure simulation?

[bush mechanics]

Menen,Oil dosnt lube valve stems(unless you have leaking valve stem seals)Its the fuel air mixture flowing thru the cylinder head that lubes valve stems(thats what the lead in the fuel does)Thats also why my ute loves AVGAS!!!PS this is what my theory books for Piston engine theory and construction said!!F@#$ CASA!!!

[Spotlight]

gottom two dollar

Hey winner, pity you know nothing about piston aircraft engines.

[VH-ELP]

Having read all of the above posts, I believe flyby_kiwi has made the overriding statement (albeit he was trying to make the opposite point) when he said "wouldn't do it in a single though". He has made an extremely good point. One must ask themselves why not in a single? The most obvious answer is that thay wouldn't because they are not prepared to risk the engine not starting again. As a grade one instructor and previous ATO who has used both methods in the past, I have now adopted the Throttle failure technique below approx 1500' as a risk management technique. I derived this idea from researching a number of official Continental and Lycoming sources directly asking specific questions relating to damage to counterweights and backpressure issues associated with the Throttle technique. It became apparent that these are only considerations if the throttle is "chopped" closed at a rapid rate.

As has been mentioned before, multi engine training requires a particularly critical amount of risk analysis between the "reality" of training scenarios vs. considerations of a/c or engine damage, terrain clearance, allowing instuctor and student a safety buffer, and good communication.

I hope this has added something worthwhile to the discussion and congratulations must be offered to centaurus for opening up an issue that is sadly now more poignant in light of a recent fatal training accident.

[bush mechanics]

Spotlight
Well Id beter get out of the engine shop then!!!!I thought Id won something! being a winner and all that.If im wrong(good chance) tell me soo with something logical.!!Isnt everthing at spotlight, CHEAP!!!!!!!!

[Bevan666]

The primary reason lead is in fuel is to increase the octane rating of the fuel. The octane rating is a measure of the fuel's ability to withstand 'knocking' (detonation).

The reason Gottem's ute loves 100LL is that as a higher octane fuel you can run the engine at a higher compression level and extract more power from the fuel.

The fact that the lead is supposed to lube the valve guides is a secondary effect (and its debatable whether there is any benefit) and its absence for a few minutes at a time will not harm an engine. (Otherwise older cars running on both leaded fuel and LPG would fall apart when running on LPG).

Also these days with the elimination of lead in mogas means none of these older cars which used to run on leaded fuel (and therefor benefiting from any lubrication of valve guides) will have had any lead in their engines for a few years. I havent heard of any mass extinction of pre 84 car engines yet.

Bevan..

[OpsNormal]

C'mon guys, have another guess. It's quite entertaining to watch the armchair experts at work talking about something they've had no training either in or with (and certainly no QUALIFICATION to do so)!

Who's got the next guess? C'mon down! :hmm:

[bush mechanics]

Hey OPS ,could you please use words i understand!!!Maybe I should have said <The valve stems get some lube from the lead in the fuel air mixture,Now being no car mechanic,Some one did tell me that early cars on LPG had special lube put on valves when installed.Im sure Unleaded fuel you buy at the servo might just have a little something mixed into it to help with lubeing valve stems and valve seats.

[Menen]

Now there's a good point. Instructors of single engine trainers don't cut the mixture for PFL or engine failure after take off because they figure the engine might not re-start for some reason or other. Good thinking - and very prudent.

In a twin, the same thing should apply. Because if you cut a mixture after take off in a twin and it doesn't re-start when you want it to, then the windmilling prop is going to cause serious drag and the aircraft will be unable to maintain speed and height.

[flyby_kiwi]

The view I had (and may not have made too clear) is that cutting the mixture on one engine in a twin will not completley stop the engine as at the IAS you would be maintaining using the live engine (at least blue line) the 'dead' engine will contine to windmill.

Once the situation is undercontrol and the student has Identified, Verifed and 'Feathered' (only coarsening the dead engine rather than retarding the pitch leaver to the full feather ident) then 'zero thrust' is set by the instuctor invloving reintroducing the mixture and setting the power and pitch settings as per the AFM so the mixture is only left cut for prehaps several seconds.

The reason for (myself anyway) not wanting to use mixture cuts in the single is that usually the a/c will have a slow best glide speed (say 65kts for a C172) and with a relativly green student it isint going to take much distraction him/her before the IAS can be back to 50kts and the prop/engine will stop windmilling altogether.

Interesting views that Ill bear in mind but admittedly had never heard of using the throttle to simultate the failure in a twin untill this thread came about.

[Bad medicine]

I had an engine refuse to re-start a long time ago as a student in a C150. The instructor failed the engine by turning off the fuel shutoff between the seats. I got too slow, the prop stopped, wouldn't restart, and we ended up in a paddock. At least I know I can do a FL now!

[permFO]

I always got the student to give me a brief on what they would do if they had an engine failure just after take-off and if it didn't include land on the available runway then I would suggest that would be a good thing to consider. I would never simulate a failure below 400' agl simply a matter of self preservation. I used to put the mixture to ICO until the boss ,also the chief LAME, set me straight on the drawbacks of using the mixture instead retarding the throttle.

[dogcharlietree]

Charles Darwin had it right -
You cut my mixture, I break your F***ing arm.
Simple.