Mixture cuts on take off revisited

[Centaurus]

Remember the Duchess that went in at Camden a couple of years back and hit the ground following a simulated engine failure of the No 2 engine? It happened at night and in the fire that followed the crash, both pilots escaped, but the instructor died of burns while the other pilot (a Canadian 767 captain) was terribly burned but survived. It is rumoured he sued CASA and won $1.4 million.

I was shown the crash site last week by the farmer that owns the property. The aircraft had done a touch and go when it was thought that the instructor chopped the right mixture control as the gear was retracting. You can still see the gap in a tall tree that the aircraft hit and where the aircraft went through a fence and hit an iron girder that tore off one wing.

The instructor was a former colleague of mine in the RAAF and actually seeing the bits and pieces still on the ground really brought it back to me the danger of "realistic" training near the ground.

It made me wonder if mixture cuts to simulate engine failure after take off are still a feature of GA twin engine flying school training? Or are the tragic lessons of the past being ignored yet again?

[Torres]

A CASA FOI pullled that stunt, unannounced, in a C208B Caravan at 300 feet AGL off 08 at Horn Island a few years ago.

It was only the skill of an experienced CP that saved them. Even at the risk of losing an AOC, a management decision was made that the FOI was no longer welcome in company aircraft.

The industry heaved a sigh of relief when he was transferred to NSW.

[Flintstone]

You mean he shut down the engine on a single engine aircraft? :eek:

[Torres]

Pulled the power lever back, unannounced, from the RH seat whilst giving the CP a "check ride".

[Flintstone]

Jeez, I thought you meant he shut the fuel off.

EFATO was a standard 'surprise' for students when I was an instructor though we at least waited to 500'.

How close to disaster did the Caravan get?

[Wombat35]

Having flown JWX, lost a mate in the 707 crash and headed STRAIGHT :eek: for the ESL tower doing VMCG training in the dog whistle, these 'exercises' should not be done unless you have a guaranteed escape option and a good brief.

However also having had 5 shutdowns on the old Bou it's important that realistic training is carried out.

From my perspective it all comes down to the brief. It should not be a surprise rather, an exercise to demonstrate the required skill. In all my engine failures, non of them have happened instantaneously so the surprise.. your engine has just failed, does not wash with me.

Well that’s my view and as it now my turn to instruct, I will always be very, very careful if nothing else out of respect for Mark and all the others that have died during a 'Practice'.

[Centaurus]

Any "training" action where the instructor actually fails the engine by turning off the fuel supply (whether it be via a mixture cut or turming of the fuel cock) at low level, is fraught with danger - unless the student is perfect in which case there is no need to ever "test" him.

A rapid throttle closure to the stops is equally dangerous especially if the pilot under "test" whacks on full wrong rudder. Been there-seen that. The check pilot or flying instructor to watch out for is the tremendously keen and utterly enthusiastic guy who might be brilliant technically, but lacks the cautiousness born of bitter experience. He will pull an engine just to see if you can "hack it" at the most stupid time just off the deck day or night. He is overconfident of his own ability to recover the situation and this is a major flaw in his makeup. The preflight briefing means nothing to this cowboy who will change the game plan because he can. He chuckles inwardly when his student is caught by surpise because he sees it as funny. Like going "Boo" to an inoffensive old goose.

[I Love This Show]

Closing the doors behind me...

I did my initial in JWX, and the instructor in question actually conducted my CPL flight test...
I've been given countless simulated failures in the Duchy, quite often it takes a good 5 mins of trying before the thing starts up again, even with un-feather working. Good thing we're always at altitude, if we needed power in a hurry we'd be stuffed

[Oktas8]

Further to Centaurus' comments regarding sudden EF's at low level -

There is a discrepancy between the training accident record and the automatic criticism of the practice of mixture cuts. When piston twins crash after a simulated EFATO, it usually seems to be from one of two causes. Either (a) it was done at such a low level that there was insufficient time to correct handling errors, or (b) power was not restored in a timely manner when it became obvious the aircraft was not performing safely.

How the engine is failed seems to be much less of a problem than where the engine was failed, and where power was restored. And this has little do with which lever is used to remove power from an engine. Sudden throttle closures would result in situations just as serious (as Centaurus said).

I'd like to see less emphasis on "it's dangerous to pull the mixture" and more emphasis on "EFATO's should be pre-briefed, and done at a pre-determined safe altitude in daylight", with instructor training including some reading of common causes of training accidents, and what could have been done differently.

Hard hat on...
O8

[2B1ASK1]

Perhaps it would be wise to ask your maintenance organisation the difference between pulling back the power lever rapidly and pulling back the mixture.

If any pilot pulled back the power lever rapidly in my BE 76 it would be the last time they sat in it. My last repair bill of $2400 for that exact action says it all, not to mention the internal stress it causes the donk.

Yes EFATO needs to be taught but working within the capabilities of the aircraft not the piolt should be the prime agenda. These aircraft were never designed for training that is not to say they are not capable of doing it.

Sadly and more than likley there will always be pilots that think they are better that the aircraft, if you want to play around the edges of the envelope then becarefull you don't get a paper cut.

As many have learnt aircraft at times bite respect the beast and it will give you many years of pleasure.

[Gear in transit]

How the engine is failed seems to be much less of a problem than where the engine was failed

I think that is an excellent point. This whole 'mixture is dangerous,' 'throttle is too harsh' is becoming a tiresom rhetoric. I think the appropriate question has been raised, as Oktas8 has said. It's about the where and why. Perhaps if we concentrated on that then there would be no mixture vs throttle debait.

[A37575]

2B1ASK1: You say that rapid throttle closure caused $2400 engine damage. What is the specific engineering proof that whatever internal damage occurred to your engine was 100% caused by fast throttle closure?

There has always been a tendency for owners to blame the hirer's for engine problems even though there has usually been a pre-existing defect. If what you say is true (and how can you prove it's true without any existing doubt?) then it is a wonder that Duchess engines are not spread all over the countryside affected by throttle closure to simulate engine failure. One rapid throttle closure should not bust an engine.

If you ask a flying instructor on single engine aircraft if he would initiate a simulated engine failure after take off at 500 ft in his single engine type by pulling the mixture control (rather than the throttle), I have no doubt he would say no bloody way.

Why would he say that? After all isn't the mixture method supposed to be "good" for the engine? He would no doubt say that there is only one engine and if the engine failed to "catch" when the mixture was advanced to rich for the ensuing climb-out, then the aircraft will in all probability crash.

He has a point there, of course; which is why in single engine aircraft good airmanship would dictate that a simulated engine failure on take off is conducted by smooth throttle closure alone.

But let's see what could happen in a twin engine aircraft if the engine failed to "catch" following mixture control advancement where the mixture cut takes place just as the wheels are selected up after lift-off (The Camden Duchess accident).

Immediately the prop is windmilling against the fine pitch stops creating massive drag (that is why we feather them) . The immediate drag causes rapid loss of airspeed and if the rpm gets too low (850 rpm is the figure according to Lycoming), it will not be possible to feather the prop to get you out of trouble. You, your student and your expensive aeroplane are history.

If those that favour mixture cuts at low level because it is realistic and good for the engine, then think again. The "student" in the Duchess accident was an experienced current Boeing 767 captain with a grade one instructors rating and multi-engine training approval. He was undergoing a night instrument rating test.

His evidence was that on lift off the instructor covered the mixture controls of the Duchess with a map then pulled back the No 2 mixture as the gear was selected up. The aircraft yawed immediately as the prop went against the fine pitch stops fully windmilling and full rudder and aileron use could not prevent further yaw.

The aircraft failed to gain altitude despite his calling to the instructor to re-start the engine immediately. The aircraft then clipped trees which further slowed its speed and the power was re-introduced far too late to prevent the aircraft from hitting a paddock, going through a wire fence and bursting into flames when a wing was split open by a iron girder in the long grass. If the simulated engine failure had been conducted by smooth throttle closure, it is likely that the accident would not have occurred as immediate recovery power could have been made.

As someone said earlier they are bored with the discussion of mixture versus throttle because a good briefing will fix everything and accidents like Camden would not occur. For your edification, a good briefing did take place prior to the accident flight, but the instructor simply changed his mind in the air.

It is unfortunate that the regulator and the investigators cry shortage of resources when it comes to investigating a GA training accident - after all in this case there was only one bloke dead, another seriously injured and some burnt grass in the paddock. Yet read about the 737 that did an extra long holding pattern at Church Creek and got a GPWS alert and the length of that report indicated no shortage of resources applied to that incident.

Don't knock the message of mixture cuts versus throttles. One man was burnt to death and the other suffered 80% burns because of someone playing silly buggers with mixtures after take off. Let's hope that instructors who indulge in these dangerous games learn a lesson from reading these Pprune pages on the subject. CASA don't seem interested enough to prevent the practice.

[Lefthanded_Rock_Thrower]

I do not think either method has merit over the other, although, doing an EFATO apon selecting gear up, means both low airspeed ( probably below VYSE ) and low Altitude, at night.

Does not appear to be a smart move.

I hold a META, i do mixture cuts, on both Carby and Injected engines and have not to this day had a problem.

The number one essential is Airspeed ( and timely control with attitude ) and then , Altitude.

Being at two hundred feet "in control" of the airspeed and conducting Phase 1 drills is relatively safe, being at 5,000 AGL below VMCA, Stall and actual VMC is dangerous.

With most of the machines we fly, in the actual configuration, 2 pilots, 2 hours fuel etc etc, VMC will more than likely be a lower airspeed than the Stall ( remember VMCA is a published airspeed, for a new aircraft, aft C of G, Isa at sea level, MTOW, critical engine ).

So would Stalling actually be much more likely than VMC roll, i.e happens at a higher airspeed.

This particular ATO had certainly forgotten more about aviation than i know, but they should not have been there.

EFATO training training below 1500 AGL at night is forbidden, refer ENR 1.1-102 ( 80.3 ), which ironically is listed as a suggested exercise in CAAP 5.23 for initial Multi. ( ??? ).

Rapid reduction in RPM can bend push rods, although very unlikely.

[Chronic Snoozer]

Whats wrong with doing it in a sim? (and only in the sim)

[Pinky the pilot]

Someone please correct me if I am wrong, but I have for a long time now been under the impression that simulated EFATO procedures at night were forbidden!
At least that is what I was told back when I did my, as it was called then, Night VMC back in 1983.
Edited; Posted the above before the left handed one added to his post! Thanks lefty! :ok:

You only live twice. Once when
you're born. Once when
you've looked death in the face.

[Lefthanded_Rock_Thrower]

Pinky,

It also states in the Legislation that EFATO below LSALT is forbidden at night, i can not remember where that little gem is.

[Dehavillanddriver]

Unless they have changed the regs in the last few years night assymetrics are NOT forbidden.

AIP (the Aeronautical INFORMATION publication) says that they shouldn't be done BUT there is nothing in the CAR's to give that snippet in AIP head of power - which means that there is nothing illegal about doing night assymetrics.

It isn't smart but NOT illegal.

It is the same as the set course within 5 miles part of AIP - it is advisory NOT mandatory because there is nothing in the regulations to give it head of power

[an3_bolt]

:eek: Intersting ideas ladies and gentlemen. Many have been here before us and have learnt the hard way. Ineterstingly Lycoming pondered about this subject in conjunction with the NTSB. Here is what they have to say about the subject from "Lycoming Flyer Key Reprints":

"The fatal crash of a light twin in which a flight instructor and an applicant for a multiengine rating were killed prompted the NTSB to issue an urgent warning to all pilots simulating an engine-out condition on multiengine airplanes. The Board’s investigation revealed that some flight instructors do use the fuel selector or the mixture control to shut down an engine to test a multiengine applicant. Although this is a recommended procedure, the urgent warning was aimed at flight instructors who were using this procedure at altitudes too low for continued safe flight.

The NTSB observed that use of such procedures at traffic pattern altitudes may not permit instructors enough time to overcome possible errors on the part of the applicant. The recommendation by the NTSB means that all simulated engine-out operation at the lower altitudes should be accomplished by retarding the throttle, and this should be done slowly and carefully to avoid engine damage or failure.

Many flight instructors down through the years used the technique of abruptly cutting an engine with a multiengine candidate to test his emotional reaction and judgment with this extreme technique. Big radial piston engines with short, stubby crankshafts could tolerate the abrupt technique. However, flat opposed piston engines with their long crankshafts and attached counterweights could not as readily take the abuse of suddenly snapping a throttle shut, particularly at takeoff or climb power. Use of the latter technique would tend to detune crankshaft counterweights and could possibly result in a nasty engine failure.

Since it was common technique by flight instructors to terminate power abruptly to simulate an engine power loss, we had to protect the engine. As a result, we published in our Engine Operator’s Manual and in Service Bulletin No. 245, the recommendation that if the power was abruptly terminated, it must be accomplished with the mixture control. Of course, this was intended for the higher altitudes where a complete engine shut-down could be conducted safely. The student was to identify the dead engine by retarding that throttle to about 12 inches MP to simulate zero thrust, or similar to having the prop feathered. At that point the instructor could immediately return the mixture to an engine operating condition and power would be available if needed

In our publications we then explained the reason for using the mixture to abruptly terminate power. By putting the mixture control in idle cutoff position with the throttle in a normal open or operating position, the pilot merely cut off the fuel, but allowed the air to continue to fill the cylinders with resulting normal compression forces that are sufficient to cushion the deceleration of the engine and prevent the detuning of the crankshaft counterweights.

However, any practice of simulated engine-out condition at low altitudes should be best accomplished by a slow retardation of the throttle in accordance with the NTSB recommendation. This careful technique will protect the engine, and at the same time provide for instant power if it is needed."

So there you have it staight from an engine manufacturer. If you close mixtures at low altitude, make sure your will is up to date and be kind enough to call the restaurant about that dinner reservation to cancel it because you most likely will not be around to use it.

Don't be stupid ladies and gentlemen. If you want to practice low level engine out work or V1 cuts etc - use a simulator - that is what they are for.

[Oktas8]

Don't knock the message of mixture cuts versus throttles. One man was burnt to death and the other suffered 80% burns because of someone playing silly buggers with mixtures after take off.
No, actually the terrible consequences happened because (a) the exercise was performed at night (b) the aircraft was well below safe height and speed and (c) power was not promptly restored. The aircraft crashed because power was cut at an unsafe time, and was not restored. All the rest is conjecture and statistical likelihoods.

(I don't mean to knock experienced opinion and statistics - both good things - but it's insulting to our intelligences to draw universal, black & white conclusions from them.)

If you close mixtures at low altitude, make sure your will is up to date and be kind enough to call the restaurant about that dinner reservation to cancel it because you most likely will not be around to use it.
No, statistically instructors have done those things for many years and gotten away with it. Please don't alienate the old-fashioned instructors or the merely ignorant by making blanket statements that are easily disproved. Can we educate instead of making inflammatory statements?

In the Duchess accident in question, I'd like to know why power was not restored before impact, as that would bring some light to the power / mixture argument - it does take a few seconds longer to restore power from ICO than it does from idle power. Now that is an argument against low level mixture cuts. So is the statistical likelihood of an engine failing to restart.

I have failed engines using mixture and using throttle; I have forgotten to set zero thrust on one or two occasions, and remembered only when I thought "now why aren't we climbing?" Good thing I only do these drills at a safe height and speed (or in the simulator)!

On another note - perhaps these exercises are performed in aircraft rather than only in the simulator because of history - it is only in recent years that simulators have become widespread in GA. Or perhaps because we GA types are too gung-ho for our own good... :E

Cheers,
O8

[an3_bolt]

I am indeed sorry Oktas8, that I may have upset you in some way. I am not tring to be inflammitory, however I can see your opinion that it might be inflammatory infering that sooner or later cutting mixtures at low level might be somewhat dangerous.

Regarding that "statistically instructors have done those things for many years and gotten away with it" is interesting also. Most individuals these days recognise that an accident or incident is proceeded by a chain of events, that contibuted or caused the final outcome. Just because a group of people have gotten away with it 1 time or 100 times, dosen't make it a safe way to do it - only a flawed way. The idea as a professional avitor is to continually review information available and the method for conducting procedures. I try to do this all the time, and indeed it has changed many of the ways I conduct myself. If a better, or safer way comes to light, why not think about it a bit. The NTSB did, and suggest an alternative method rather than cutting mixtures at low level. And I believe they did look at the statistics.

In any case - good luck. Safe flying to you all.

[A37575]

From reading the Lycoming statement, it does indeed explain why a mixture cut is preferable to throttle closure in order to simulate failure. It seems it's all about having the throttle wide open to "cushion" piston movement. What is not said, however, is that as part of the identification process (dead side dead leg, primary), the "dead" throttle is closed as a secondary confirmation.

And as soon as you close the dead throttle which is about 5 seconds after dead side dead leg, the "cushioning" advantage supplied by the wide open throttle is shot to pieces.

[Oktas8]

No offense here an3_bolt, and I agree with everything in your most recent post. I agree too that low-level mixture cuts are somewhat risky.

It's actually because I have tried to put a lot of thought into this issue that I dislike the oversimplification of "throttle good, mixture bad".

My current employer discourages mixture cuts at any stage in flight, but makes no comment about rapid throttle cuts at as low a height as you like. In terms of pilot education, I think that we can do better than that.

Cheers again,
O8 :)

[wateroff]

Something for the student's.

If you think or feel what is happening is unsafe -SPEAK UP. Don't take the person sitting beside you as god. There are those out there with a God complex, and have derived their own parameters, gold bars do not mean quality/experience. Understand everything that is going to happen thru the flight. The old rule - not briefed - not done. If they pull something on you, that you feel is not right - SPEAK UP.

Something for the Instructors

Thankfully there a more good and safe teachers than there are these -
"oh but they have to see what happens when you have a double engine failure with no flaps or gear and your in cloud with 40 knots crosswind and fouled controls". Sadly I have met some.

A bit rough I know, but Safety first, ego last.

[Centaurus]

Wateroff. Well said...

[2B1ASK1]

A37575

To further explain the difference between the throttle closure over the mixture. It is realy rapid closure of the throttle that damages the engine when a throttle is closed rapidly from full power the fuel is still pumping out at a rapid rate now being un-burnt and pumped into your exhaust system. Suddenly bang as it ignites blowing your exhast system apart or worse damaging your engine or causing a fire.

My bill was for a new baffle assembly and inspection I do not need specific proof I have been working as a LAME/AME for over 26 years. It happens not often but it happens, the nature of simulated eng failures usually has an element of surprise to get the surprise the action is often rapid closure.

The real issue is at what time it is done, I have never seen the need for any low level practise, actual failure is rare and we are dealing with assymetric flight which can be simulated at higher levels using the hard deck method the military have for their combat training.

[Ozgrade3]

The company I worked for specified mixture cuts for simulated engine failurs except for AFATO below 500' when the throttle should be used. In this case I close the throttle smoothly and slowly. You know if you have closed the throttled too rapidly if it pops and farts. I didnt know it was fuel actuallyburning in the exhaust system, that quite scarey.