Go Back  PPRuNe Forums > PPRuNe Worldwide > The Pacific: General Aviation & Questions
Reload this Page >

Simulated engine failure after take off in light piston engine twins

The Pacific: General Aviation & Questions The place for students, instructors and charter guys in Oz, NZ and the rest of Oceania.

Simulated engine failure after take off in light piston engine twins

Old 9th Jun 2017, 10:34
  #41 (permalink)  
 
Join Date: Nov 2000
Location: Salt Lake City Utah
Posts: 3,052
I used to be alarmed at the level of ignorance manifested by these mixture v throttle cut simulated engine failure threads. These days I'm just sad.

Sad because I've come to the conclusion that the level of stupid-proofing of most piston engined aircraft fuel systems will always be what it is, the level of ignorance in the pilot/instructor population will continue to be whatever it will be, and therefore the rate of training-induced accidents will continue to be whatever it is.

It's as if no one has ever looked under the cowls and studied the fuel systems of various aircraft and noticed that not all fuel systems are the same.

Sad.
Creampuff is offline  
Old 9th Jun 2017, 10:38
  #42 (permalink)  
 
Join Date: Sep 2002
Location: Enzed
Posts: 2,184
A37575

Two points from your post.

The accident you quote in your post is a prime example of what I was talking about, - Inappropriate simulations. A touch and go in this scenario is always risky no matter the engine failure method, see my comment below. In my view the prime cause was the decision to carry out the touch and go without first knowing the engine would respond properly.

Secondly, seriously how long does it take to restore power after a mixture cut. You make it seem like it's a drawn out process. It's not. If there's not sufficient time then the timing of the simulation is inappropriate no matter the method you use.

One last point, everyone seems to be forgetting the incidents and accidents that have occurred when the engine has failed to respond on a PFLWOP that has been initiated by closing the throttle.
27/09 is offline  
Old 9th Jun 2017, 12:10
  #43 (permalink)  
 
Join Date: Aug 2011
Location: Australia
Posts: 371
One last point, everyone seems to be forgetting the incidents and accidents that have occurred when the engine has failed to respond on a PFLWOP that has been initiated by closing the throttle.
As you rightly say, there have been numerous events of the type you describe. While it is usually difficult to say for certain the reason the engine has failed to respond on practice forced landings, especially if there was no obvious mechanical failure, investigations have usually pointed out the weather conditions were conducive to carb icing; exacerbated by the pilot forgetting to use or incorrectly using, carb heat during prolonged glide at idle power. That is an entirely different subject to the discussion points on this thread
sheppey is offline  
Old 9th Jun 2017, 20:53
  #44 (permalink)  
 
Join Date: Sep 2002
Location: Enzed
Posts: 2,184
Originally Posted by sheppey View Post
As you rightly say, there have been numerous events of the type you describe. While it is usually difficult to say for certain the reason the engine has failed to respond on practice forced landings, especially if there was no obvious mechanical failure, investigations have usually pointed out the weather conditions were conducive to carb icing; exacerbated by the pilot forgetting to use or incorrectly using, carb heat during prolonged glide at idle power. That is an entirely different subject to the discussion points on this thread
No doubt some of the incidents were caused by carb icing however in my experience plug fouling as a result of extended low power (idle) settings is prevalent as well.

My main point is I don't believe there is any material difference from a safety point if view between the two methods and the precursor of most single OEI training accidents is the exercise being carried out in an inappropriate manner.
27/09 is offline  
Old 10th Jun 2017, 00:26
  #45 (permalink)  
 
Join Date: Aug 2011
Location: Australia
Posts: 371
My main point is I don't believe there is any material difference from a safety point if view between the two methods
The manufacturer would have access to a large data base of incidents and accidents for their aircraft and from this would not have lightly published this recommendation. Nor would have the NTSB in its warning. Best of luck with your mixture cuts in future. Don't tell CASA though...


The Piper Seminole Information Manual at Section 10, entitled Training Tips states:
“Experience has shown that the training advantage gained by pulling the mixture control or turning off fuel to simulate engine failure at low altitude, is not worth the risk assumed, therefore it is recommended that instead of using either of these procedures to simulate loss of power at low altitude, the throttle be retarded slowly to idle position”.
............................................................
sheppey is offline  
Old 10th Jun 2017, 01:14
  #46 (permalink)  
 
Join Date: Jan 2008
Location: Australia
Posts: 221
Originally Posted by sheppey View Post
... from this would not have lightly published this recommendation. Nor would have the NTSB in its warning.
Don't underestimate the enormous amount of arse-covering that goes on in this industry. If someone in the manufacturer, FAA, CASA, etc can point to "I said that X might be a problem", then they feel safer - even though there may be good reasons to do X under some (or even many) circumstances.

The important thing is that we consider and evaluate pluses and minuses in situ ... avoiding anything potentially linked to a minus does not lead to competent pilots or good training.
drpixie is offline  
Old 10th Jun 2017, 03:14
  #47 (permalink)  
 
Join Date: Nov 2000
Location: Salt Lake City Utah
Posts: 3,052
The manufacturer would have access to a large data base of incidents and accidents for their aircraft and from this would not have lightly published this recommendation. Nor would have the NTSB in its warning. Best of luck with your mixture cuts in future. Don't tell CASA though...

The Piper Seminole Information Manual at Section 10, entitled Training Tips states:
“Experience has shown that the training advantage gained by pulling the mixture control or turning off fuel to simulate engine failure at low altitude, is not worth the risk assumed, therefore it is recommended that instead of using either of these procedures to simulate loss of power at low altitude, the throttle be retarded slowly to idle position”.
............................................................
Again, the number of misconceptions manifested by the material in that post is saddening.

I'll bet that the 'use the throttle rather than mixture control' crowd believe that:

- Pulling the mixture completely shuts off fuel to the engine, and

- This is true for all engine/airframe combinations.

Both are demonstrably wrong generalisations. However, the demonstration requires an understanding of how the different fuel systems fitted to different engines and different aircraft behave differently. Better, instead, to stick with the blissful ignorance that pulling the throttle will always be less risky than pulling the mixture to simulate an engine failure, no matter the aircraft and no matter the engine.

The only real-life failure of a piston engine to respond after a simulated engine failure of which I am aware was simulated by pulling the throttle. An understanding of the specific fuel system and specific engine fitted to that specific aircraft made it obvious why that method of simulation was no more likely than pulling the mixture to end in a failure to respond when trying to obtain full power. (Not a carby icing problem, BTW. Injected engines don't have a carby.)

Procedures on some aircraft require an electric fuel pump to be on for e.g. Take-off. Procedures on other aircraft warn against the use of an electric fuel pump for e.g. Take-off. How could both be correct, if all fuel systems on all piston engines and all aircraft are the same?

Engine designers and manufacturers, airframe designers and manufacturers, engine maintainers, airframe maintainers, regulators, accident investigators and insurers all have a vested interest in saying that if only the pilot had done something different from what they did, the damage/accident/incident would not have occurred. The difference between correlation and causation is often (conveniently) overlooked.
Creampuff is offline  
Old 10th Jun 2017, 05:23
  #48 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 3,828
From revisiting all these posts it is clear there are two camps. Ops normal in many discussions where strong opinions are aired. I have yet to see in any pertinent document produced by manufacturers or State regulatory authorities that closing the throttle to simulate an engine failure after take off is not recommended for reasons of flight safety. Perhaps the wording should be amended to Human Factors. In other words almighty cock up's by one or other of the crew.

On the other hand we have seen in these posts documentary evidence from two State regulatory authorities (CASA and UK CAA) as well as the US NTSB, that mixture cuts used to simulate engine failures after take off are not recommended for flight safety reasons (i.e. Human Factors) A further CASA flight safety document CAAP states the same thing.

Reminds me of the adage traced back to Year 1546 "There are none so blind as those who will not see."
Centaurus is offline  
Old 10th Jun 2017, 10:33
  #49 (permalink)  
 
Join Date: Nov 2000
Location: Salt Lake City Utah
Posts: 3,052
At least for my part, I'm in neither "camp". It's a false dichotomy that is a manifestation of the problem.

I'm happy to be in a piston aircraft in which engine failures are simulated by pulling the throttle, provided that that happens to be the least risky way to simulate failures on that specific aircraft with that specific fuel system and engine.

I'm also happy to be in a piston aircraft in which engine failures are simulated by pulling the mixture, provided that that happens to be the least risky way to simulate failures on that specific aircraft with that specific fuel system and engine.

I'm never happy to be in a piston aircraft in which the instructor or ATO is chock full of one-size-fits all rules.

That even regulatory authorities can suggest that one method is generally less risky than another just demonstrates that old wives' tales, like weeds, take hold everywhere. Appeals to authority never impress me.
Creampuff is offline  
Old 10th Jun 2017, 13:32
  #50 (permalink)  
Man Bilong Balus long PNG
 
Join Date: Apr 2002
Location: Back in the land of the Rising Sun for another three months of Glider towing, eating great Japanese food, perving on lovely Japanese Ladies and continuing that search for a bad bottle of Red.
Age: 64
Posts: 2,527
I did the second half of my CPL and my MECIR in a Seneca 1 with an Instructor who is still well known and respected with, shall we say, `older` Pilots in the Industry.

His initials are IAK, better known as TK.

His technique for simulated engine failures were; After Take off, using the mixture, hiding the levers behind something handy. Sometimes he would hide the levers but not fail an engine, just to keep you on your toes!!

In level flight at a safe cruising altitude he would turn the fuel off! Generally when he reached for a cigarette because he kept the packet on the fuel selectors!

I don`t know if he ever twigged but whenever I saw his hand go down to his fag packet, I knew an engine was about to `fail.`

I have no argument with all the simulated failures he gave me, and they were countless!

Simply because I am convinced that they more than adequately prepared me for the three genuine failures I subsequently experienced in my later flying time in PNG.

Even if they were in Bongo Vans!
Pinky the pilot is offline  
Old 10th Jun 2017, 20:56
  #51 (permalink)  
 
Join Date: Dec 2004
Location: back to the land of small pay and big bills
Age: 45
Posts: 1,043
Maybe for engine failures in the cruise but if you're doing mixture cuts in the circuit you should bloody well do it by yourself and not endanger your students...some people just think their lives aren't exciting enough!
mattyj is offline  
Old 10th Jun 2017, 21:15
  #52 (permalink)  
 
Join Date: Nov 2005
Location: US
Posts: 51
The ATO himself/herself, and not the student, has failed the test if mixture or fuel off is used to generate the failure on take-off.

Under any analysis, that's putting the aircraft at significant risk.

I don't even know why this discussion is still occurring.
mrs nomer is offline  
Old 11th Jun 2017, 03:52
  #53 (permalink)  
 
Join Date: Jul 2001
Location: Australia
Posts: 4,840
Folks,
For may years, I worked with an operator with a well deserved reputation for risk minimization ( inaccurately aka "safety") and I have always been happy with their logic, and applied it to my own operations.
ALL their aircraft were certified with whatever were the DCA/CAR/FAR transport standards of the day, which all included a certified "stop/go" capability in the event of engine failure.

NOT a feature, generally, of FAR 23 aircraft.

The training rules were really quite simple:
(1) The only time you shut and engine down (by the approved method) and feathered was above 3000'minimum, 6000'+ preferred AGL, daylight, VMC.
(2) All engine failures on takeoff, and any related operation below 3000', simulate the failure by SLOWLY retarding the throttle, sufficient to ensure the student/candidate correctly identified the failed engine, and then manipulating the manifold pressure/RPM to simulate a feathered prop.
(3) NO simulated asymmetric at night.
(4) Going beyond the above was a dismissal offence, such was the risk analysis of any training value versus the increased opportunity for disaster, almost always fatal.

Works for me, and for anybody who works for me.

The FAA, some years ago, published an interesting analysis of outcomes of in-flight engine failures in singles versus twins, as always most instructive.

In short, subsequent to the failure, the fatal accident rate for the landing heavily favored the single, and where the twin resulted in a major accident was almost always because of asymmetric mishandling, resulting in loss of control in flight (there is some sobering in-flight genuine footage on YouTube, illustrating how sudden and violent it can be getting below Vmca in a FAR 23 twin), whereas most singles arrived back at ground level more under control than less.

In other words, a FAR 23 twin is not just a single with twice the chance of engine failure, it is worse than that.

Tootle pip!!
LeadSled is offline  
Old 12th Jun 2017, 07:31
  #54 (permalink)  
 
Join Date: Nov 2000
Location: Salt Lake City Utah
Posts: 3,052
The ATO himself/herself, and not the student, has failed the test if mixture or fuel off is used to generate the failure on take-off.

Under any analysis, that's putting the aircraft at significant risk.

I don't even know why this discussion is still occurring.
The discussion is still occurring because there are still people who'd like matters of aviation safety to be determined by data and rational decision-making that takes the data and relative risks into account.

I can show you a certified and confirmed serviceable aircraft (including a confirmed serviceable fuel system) whose engine will continue to run even with the throttle closed and the mixture set to idle cut-off. How can that be so?

On "any" evidence-based "analysis", pulling the mixture control does not have the effect of turning the "fuel off" on many aircraft. On "any" evidence-based "analysis", on some aircraft the simulation of an engine failure by pulling the throttle produces an operational environment that is unrealistic of the usual causes of engine failures.

Don't you think it would be safer if the method of simulation was decided on the basis of an understanding of the particular systems on the aircraft in which the simulation is occurring, and a consequent understanding of which method is - on balance - least unsafe?
Creampuff is offline  
Old 12th Jun 2017, 11:47
  #55 (permalink)  
 
Join Date: Apr 2005
Location: Australia
Posts: 1,400
Don't you think it would be safer if the method of simulation was decided on the basis of an understanding of the particular systems on the aircraft in which the simulation is occurring, and a consequent understanding of which method is - on balance - least unsafe?

You are making a mountain out of a mole hill. The object of training for an engine failure in a twin engine type as above, is a handling issue pure and simple in that the pilot applies flight controls to keep the aircraft right side up.
It would be unrealistic to conduct engineering flight tests for a Tiger Moth to a Cirrus or for a DC3 or to a Seminole and all types in between, to determine whether a throttle closure or fuel/mixture cut is most desirable from engine handling point of view.

In a single engine types such as typical Cessna or Warrior, it is normal to close the throttle to simulate engine failure for a practice forced landing. Why not cut the mixture to simulate the engine failure in a single? Answer: It may not start again and you are left with a real forced landing with its associated obvious drawbacks.

Yet some are happy to cut the mixture to simulate engine failure on a twin. Fine above circuit altitude with time and altitude to spare. But what if that engine doesn't start again? For one you are stuck with a windmilling prop until the penny drops you have a serious handling problem and you are forced to feather the prop for real. Not much fun at low altitude after take off and steadily degrading airspeed.

A pedant would claim the mixture cut at low altitude is good from the engine handling point of view and that this overrides safety considerations. Someone else may have the view that safety considerations override engine handling considerations and for that reason prefer to close the throttle to idle and thus have instant power available if needed

This is the point made succinctly in the warnings via various State safety authorities and the NTSB that all things considered, mixture cuts in twins at low level to simulate engine failure, are simply not worth the risk of mishandling by a student/instructor. Perhaps the time has come to realise the subject in PPRuNe has run its course with people agreeing to disagree.
A37575 is offline  
Old 12th Jun 2017, 12:39
  #56 (permalink)  
 
Join Date: Mar 2008
Location: Richmond NSW
Posts: 1,206
Originally Posted by A37575 View Post
You are making a mountain out of a mole hill. The object of training for an engine failure in a twin engine type as above, is a handling issue pure and simple in that the pilot applies flight controls to keep the aircraft right side up.
If only it was that simple. There's been a number of double fatalities over the years in Australia, where the instructor also lost control while simulating an EFATO in a piston twin.

Creampuff's argument appears to me to be: That not all piston twin aircraft have similar engines nor fuel systems. So there's no 'one size fits all' on how to do EFATO's in a twin.

Understanding how your aircraft's engines and fuel systems really work must add to the safety of your flying. (And I don't mean some of the OWT's that many of us learnt from our GA instructors, all those years ago.)
gerry111 is offline  
Old 12th Jun 2017, 23:04
  #57 (permalink)  
 
Join Date: Aug 2004
Location: Melbourne, Australia
Posts: 7,247
I think the point here is that there are Two issues mixed up here; training and qualification.

By definition training involves the possibility of the student failing at first attempts to perform the required action. Hence there must be an allowance made for the instructor to rectify mistakes in good time.

As for qualification. I fail to understand the logic in assuming that if a pilot can handle EFATO once during a test, they can therefore handle the same failure, possibly in a different environment in future.

Then there is the argument for professionals about the risk mitigation possibilities in actually performing an EFATO. Clearly, training fatalities suggest that a realistic practice is as dangerous as the real thing.

To put that another way, does one test the operation of a firearm safety catch by loading the weapon, pointing it at your head and attempting to pull the trigger?
Sunfish is online now  
Old 13th Jun 2017, 02:08
  #58 (permalink)  
 
Join Date: Jan 2007
Location: Qld troppo
Posts: 3,471
Would be interesting to see some stats on engines that have failed to restart after the mixture was used in an EFATO drill - with the engine to being returned to zero trust immediately after the 15-20 secs to complete or stuff up the drill, not left shut down with or without the prop feathered.

Seems to me that when you hear or read about an EFATO drill that has gone bad there is likely to me more to it than just using the mixture to briefly shut down thrust from the engine.

Dr
ForkTailedDrKiller is offline  
Old 13th Jun 2017, 11:18
  #59 (permalink)  
 
Join Date: Sep 2002
Location: Enzed
Posts: 2,184
Originally Posted by ForkTailedDrKiller View Post
Would be interesting to see some stats on engines that have failed to restart after the mixture was used in an EFATO drill - with the engine to being returned to zero trust immediately after the 15-20 secs to complete or stuff up the drill, not left shut down with or without the prop feathered.

Seems to me that when you hear or read about an EFATO drill that has gone bad there is likely to me more to it than just using the mixture to briefly shut down thrust from the engine.

Dr
I agree with your last sentence.

I have no idea how many engine failures I have initiated as an instructor but it would be in the 1000's. They have been initiated both by closing the throttle and by mixture cuts. The only method that has ever caused me to wonder if the engine is going to come back to normal power have been those initiated by closing the throttle.
27/09 is offline  
Old 14th Jun 2017, 06:46
  #60 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 2,744
To put that another way, does one test the operation of a firearm safety catch by loading the weapon, pointing it at your head and attempting to pull the trigger?
Some folks do that Sunny, but they have the safety in the off position to see if it works. And it usually does.
megan is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.