Low altitude mixture cuts in twin training still occuring despite CASA warnings
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A37575, going back to your opening statement:
What does using the mixture have anything to do with the student losing control? The same thing would have happened if the throttle was closed. I'm sure you've got some very good experience and teaching techniques, but you're arguing the wrong point here.
I thought CASA had banned mixture cuts on take off following the earlier Duchess crash? Either way, that technique is fraught with danger of mishandling by either the instructor, the student or both. These two crashes and others before them prove that instructors should not risk the lives of their students with dangerous practices in attempts at realism.
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Avgas, hopefully you've read through some of the posts after yours, which included advice from the engine manufacturer. Pulling the mixture, in most training aircraft since about 1960, does not shut down the engine at all. If the prop stops spinning, which will prevent the reapplication of fuel creating power due to no spark, there's a good chance you've lost control anyway as the speed has dropped below Vmc.
Kharon, for the first time ever I agree with you.
The "Lycoming Flyer" newsletter is a reasonably authoritive source of engine handling information. The last edition of Lycoming's "Key Reprints" 2002 made the following point under the heading of National Transportation Safety Board Warning on Simulated Engine-Out Maneuvers. .
The fatal crash of a light twin in which a flight instructor and an applicant for a multi-engine 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 carefully retarding the throttle and this should be done slowly and carefully to avoid engine damage or failure. This careful technique will protect the engine and at the same time provide for instant power if it is needed.
I am sure an aviation lawyer would make good use of this statement if needed in a civil case against an instructor involved in an accident such as both Camden accidents referred to in the initial post.
The fatal crash of a light twin in which a flight instructor and an applicant for a multi-engine 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 carefully retarding the throttle and this should be done slowly and carefully to avoid engine damage or failure. This careful technique will protect the engine and at the same time provide for instant power if it is needed.
I am sure an aviation lawyer would make good use of this statement if needed in a civil case against an instructor involved in an accident such as both Camden accidents referred to in the initial post.
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.
And pattern altitude means 1000' agl ---- but, Hey!! What would the NTSB (or the FAA for that matter) know, compared with our "experts".
By the tone of this thread, the fatal twin training accidents at Camden, Bankstown, Archerfield,Tamworth etc. will continue ---- as CASA individuals FOIs make it clear to instructor that "engine failure" means engine failure, none of this whimpy zero thrust nonsense.
After all, "compliance" is the watchword, non-compliance is a strict liability offense. (Creamie --- don't get all pedantic on me --- you know what I mean)
And the instructor/ATOs haven't got the courage and common sense to tell them where to go!
It is a simple fact that we have killed a steady stream of candidates and instructors with EFATO training, compared to the very rare fatalities from "real" engine failures.
This is what contributes to the fact that we have a lousy record for air safety outcomes, compared to the US.
Tootle pip!!
PS: The "student" who was the last fatality at Camden was a Captain with an American airline, with significant and recent GA experience, the instructor asked too much of an aircraft not certified for what he tried to do.
As I recall, the instructor (who has a well deserved reputation for frightening students fartless with his EFATO practices, died the following day.
His poor bloody victim took months to die of his injuries. Dying of massive burns is not a nice way to go.
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CASA individuals FOIs make it clear to instructor that "engine failure" means engine failure, none of this whimpy zero thrust nonsense.
Avgas and others, I guess we'll agree to disagree that the engine was shut down. As mentioned previously, power was immediately available once the mixture was restored. This method was different to that of some pilots who used fuel shut offs etc to kill the engine. That is an entirely different kettle of fish that I don't support as a delay could be expected restoring power using such an approach.
27/09
When I did my inital multi, I was taught to identify the failed engine using the 'dead leg, dead engine' technique, and the confirm by slowly reducing the appropriate throttle and noting any change in the yaw etc.
Surely looking at the guages instead of outside/AH trying to ascertain which engine has failed would do nothing but cause problems?
When I did my inital multi, I was taught to identify the failed engine using the 'dead leg, dead engine' technique, and the confirm by slowly reducing the appropriate throttle and noting any change in the yaw etc.
Surely looking at the guages instead of outside/AH trying to ascertain which engine has failed would do nothing but cause problems?
You need to check the gauges as well.
If the yaw that you're using to decide if there's a failure event is instead caused by an increased power output on the *other* engine you will have the same symptoms ie a yaw away from the most thrust side, even though the 'yaw towards' side is running normally. Also many failures aren't a clean 'stop'. The failing engine coughs & farts & surges then repeats - causing lots of repeated left & right yawing.
Both of the types above need the pilot to check the gauges to ascertain which is the causative engine. In some cases you'll need to watch the gauges for a bit to see a pattern, including checking for the correct readings on the 'good' engine.
If the yaw that you're using to decide if there's a failure event is instead caused by an increased power output on the *other* engine you will have the same symptoms ie a yaw away from the most thrust side, even though the 'yaw towards' side is running normally. Also many failures aren't a clean 'stop'. The failing engine coughs & farts & surges then repeats - causing lots of repeated left & right yawing.
Both of the types above need the pilot to check the gauges to ascertain which is the causative engine. In some cases you'll need to watch the gauges for a bit to see a pattern, including checking for the correct readings on the 'good' engine.
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Forget the bloody endless, pointless puerile mixture/ bloody throttle argument. Look at the 'real' cause of the Camden prang, and praise the very experienced man who saved 'em. Both.
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Which Throttle's Frozen?
I'm having difficulty accepting students in twin endorsement training are having trouble identifying a dead engine. How can this be? In either visual or (simulated) IFR conditions, identifying a dead engine on a traditional twin is such a primary task, and I believe a very simple one, I am surprised it keeps coming up on here. How can a student bugger up identifying a non-powered engine, particularly after thorough pre-flight briefings? Almost rhetorical question: Are the latter not conducted anymore?
I'm having difficulty accepting students in twin endorsement training are having trouble identifying a dead engine. How can this be? In either visual or (simulated) IFR conditions, identifying a dead engine on a traditional twin is such a primary task, and I believe a very simple one, I am surprised it keeps coming up on here. How can a student bugger up identifying a non-powered engine, particularly after thorough pre-flight briefings? Almost rhetorical question: Are the latter not conducted anymore?
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My observation has been that some instructors become a little complacent at times. Late afternoon sorties are a typical scenario. I am guilty of this and learned the hard way. You alwyas have to expect the unexpected. I note many posts refer to the loss of control....thats exactly what it was, a loss of control due to mishandling. So many students/candidates do not carry out the most important requirement....fly the aircraft......stop the yaw....control your airspeed. Airspeed and Altitude, if you've got one of these you have half a chance, but if you have neither, no chance.
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Regarding checking instruments - this needs to be treated with extreme caution.
In most light twins, during the take-off and initial climb it is likely the engines are generating their max power anyway, so it is unlikely a further increase could occur. Possible, such as a prop runaway, but unlikely.
The instruments on a dead engine can seem very live. What's the MP pressure on an engine providing no power? Somewhere around 29-30" depending on the conditions. Unless feathered, a prop could still be providing 22-2300 rpm while it windmills. These two indications can make the engine look like it is providing power during the heat of battle.
A PA31 incident at Archerfield many moons ago proves this. The pilot believed he was still generating power based on what he saw on the instruments and elected not to secure the failed engine. It took him around 12nm to climb to 1000 odd feet, but hey, he must have been generating power right? Subsequent investigation found he saw close to what I spoke about before.
While an increase in power can lead to misidentification of a failed engine, one needs to pick the time and place to start feeding this info to fresh, overwhelmed minds.
In any case, moving the throttle through its travel, and checking there was no change in yaw or noise, should allow you to identify whether there is a problem and avoid securing a perfectly good engine.
In most light twins, during the take-off and initial climb it is likely the engines are generating their max power anyway, so it is unlikely a further increase could occur. Possible, such as a prop runaway, but unlikely.
The instruments on a dead engine can seem very live. What's the MP pressure on an engine providing no power? Somewhere around 29-30" depending on the conditions. Unless feathered, a prop could still be providing 22-2300 rpm while it windmills. These two indications can make the engine look like it is providing power during the heat of battle.
A PA31 incident at Archerfield many moons ago proves this. The pilot believed he was still generating power based on what he saw on the instruments and elected not to secure the failed engine. It took him around 12nm to climb to 1000 odd feet, but hey, he must have been generating power right? Subsequent investigation found he saw close to what I spoke about before.
While an increase in power can lead to misidentification of a failed engine, one needs to pick the time and place to start feeding this info to fresh, overwhelmed minds.
In any case, moving the throttle through its travel, and checking there was no change in yaw or noise, should allow you to identify whether there is a problem and avoid securing a perfectly good engine.
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Agreed! Never go to your instruments initially. If unsure of which donk has failed or which way the nose has yawed.....look at the ball on the turn coordinator, kick the ball to the centre square!
Just to wrap up discussing my method, once the failed engine had been identified, verified and the student touched the appropriate pitch lever (calling feather left/right), zero thrust would be set.
And the point of my comment is that individuals in CASA will cancel your twin training approvals for this ----- as, in their current view, it does not conform with their "legal" interpretations that the engine must be "failed", to "simulate" an engine failure.
As to the views about the last Camden accident, the instructor did a good job??? Please explain??
Tootle pip!!
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If the yaw that you're using to decide if there's a failure event is instead caused by an increased power output on the *other* engine you will have the same symptoms
need the pilot to check the gauges to ascertain which is the causative engine
Unless you're in IMC, your eyes should be outside the aircraft. Gauges are a cross-check, but they should only confirm what you already know.
Last edited by Unhinged; 16th Sep 2011 at 02:46.
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quote: WTF is selah?
answered with google ....
cheers
A172
Selah (Hebrew: סֶלָה, also transliterated as selāh) is a word used frequently in the Hebrew Bible, often in the Psalms, and is a difficult concept to translate. (It should not be confused with the Hebrew word sela‘ (Hebrew: סֶלַע) which means "rock.") It is probably either a liturgico-musical mark or an instruction on the reading of the text, something like "stop and listen". "Selah" can also be used to indicate that there is to be a musical interlude at that point in the Psalm.[1] The Amplified Bible states Selah as "pause, and think of that".
cheers
A172
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LeadSled,
Not in my neck of the woods. In fact, it was a CASA FOI who changed my technique from throttle to mixture.
But I guess there lies the problem. No consistency from them, some strange ideas about how things should be done, yet they expect instructors to know the square root of the pickle. One of the major reasons I had to get out of instructing.
Lead, regarding your last comment asking whether the pilot did a good job, not sure if that was aimed at me or someone else. I wouldn't have a clue about that particular case, but I wanted to join in the debate about multi training. There was some strange stuff being posted, which needed balance in case any new or aspiring meta instructors were reading.
Not in my neck of the woods. In fact, it was a CASA FOI who changed my technique from throttle to mixture.
But I guess there lies the problem. No consistency from them, some strange ideas about how things should be done, yet they expect instructors to know the square root of the pickle. One of the major reasons I had to get out of instructing.
Lead, regarding your last comment asking whether the pilot did a good job, not sure if that was aimed at me or someone else. I wouldn't have a clue about that particular case, but I wanted to join in the debate about multi training. There was some strange stuff being posted, which needed balance in case any new or aspiring meta instructors were reading.
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May I put another foot in the water and ask what's the current acceptance and/or procedure for single engine approach and landings in a conventional twin? It was done in my day, I have no idea now.
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I do. At the very least one full feather-shutdown-secure-and-landing in an endorsement, and preferably two or three. Also at least one gear failure and manual extention. And any other emergency that I can safely demonstrate in the aircraft.
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If CASA want you to shutdown and feather the prop to simulate the failure, they're going against their own documentation. From the CAAP, feathering not recommended:
Propellers should never be feathered in flight during training below 3000 ft above ground level (AGL).
Finally, CASA strongly recommends that, when practicing asymmetric flight, an aircraft should never be landed with the propeller of a serviceable engine feathered. The risk far outweighs the minimal benefits, with abundant examples of such unnecessary risks proving fatal. If a landing with a feathered propeller on a serviceable engine is contemplated, a
comprehensive risk assessment should be made and a clear plan developed. The plan should include weather, traffic air traffic control and any other factors
But nothing says you can't use the mixture to simulate the failure. It only talks about the throttle being kinder to the engine, which has previously been proven incorrect.
5.5.2 Instructors must emphasise that during a practice
engine failure, when the throttle is closed and the propeller is
windmilling this replicates the situation of high propeller
drag that exists until the propeller is ‘simulated feathered’,
when zero thrust is set. Slowly closing the throttle is
probably one of the methods used to simulate an engine
failure. Although selecting idle cut-off may be kinder to an
engine, the engine or aircraft manufacturer may not permit
it, so slowly closing the throttle to idle or zero thrust is
unlikely to harm the engine and allows for immediate
restoration of power. When setting zero thrust (only after the
student has completed the simulated feathering), throttle
movements should not be rapid, and of course the student
should have been briefed about your actions.
Propellers should never be feathered in flight during training below 3000 ft above ground level (AGL).
Finally, CASA strongly recommends that, when practicing asymmetric flight, an aircraft should never be landed with the propeller of a serviceable engine feathered. The risk far outweighs the minimal benefits, with abundant examples of such unnecessary risks proving fatal. If a landing with a feathered propeller on a serviceable engine is contemplated, a
comprehensive risk assessment should be made and a clear plan developed. The plan should include weather, traffic air traffic control and any other factors
5.5.2 Instructors must emphasise that during a practice
engine failure, when the throttle is closed and the propeller is
windmilling this replicates the situation of high propeller
drag that exists until the propeller is ‘simulated feathered’,
when zero thrust is set. Slowly closing the throttle is
probably one of the methods used to simulate an engine
failure. Although selecting idle cut-off may be kinder to an
engine, the engine or aircraft manufacturer may not permit
it, so slowly closing the throttle to idle or zero thrust is
unlikely to harm the engine and allows for immediate
restoration of power. When setting zero thrust (only after the
student has completed the simulated feathering), throttle
movements should not be rapid, and of course the student
should have been briefed about your actions.