Courting disaster by "demonstrating" Vmca
Join Date: Jun 2001
Location: Australia
Posts: 889
Likes: 0
Received 0 Likes
on
0 Posts
Posted separately from the Vmc post...
Regarding EF during the take-off roll:
There is one alternative Centaurus - prompt selection of live engine mixture to ICO. That's the instructor's job. Generating the EF at a speed that allows time for the instructor to do this without running off the runway is also the instructor's job.
Better to do this in a simulator as you suggest. But if impossible, an instructor with a hand over the mixtures is at significantly lower risk than one without.
We all know it requires instant corrective rudder while simultaneously rapidly closing the live engine throttle.
In fact the student's corrective action must be perfect and instantaneous at first go in every respect.
Better to do this in a simulator as you suggest. But if impossible, an instructor with a hand over the mixtures is at significantly lower risk than one without.
Thread Starter
On a similar vein of risk taking, there are many instructors who are perfectly happy to simulate engine failure shortly after take off in a twin by cutting a mixture control (rather than simply retard a throttle). However, when asked would they simulate an engine failure say at 500 ft after take off in a single engine aircraft by cutting the mixture, the answer is generally "you gotta be joking, mate - too dangerous. What if the engine doesn't pick up when you move it back to rich for the go-around?"
Fair enough question, too. Then why risk the same mixture cut in a twin which may also result in the engine not picking up when ready? By the time you realise it hasn't picked up the airspeed will have decayed dangerously with a windmilling prop and with all that drag on one side it the aircraft may not climb and in fact directional control lost if speed is well below blue line.
Morale? Safer option is to use the throttle closure method of simulating an engine failure in a twin - don't you agree?
Fair enough question, too. Then why risk the same mixture cut in a twin which may also result in the engine not picking up when ready? By the time you realise it hasn't picked up the airspeed will have decayed dangerously with a windmilling prop and with all that drag on one side it the aircraft may not climb and in fact directional control lost if speed is well below blue line.
Morale? Safer option is to use the throttle closure method of simulating an engine failure in a twin - don't you agree?
I know the original question came from Auz but most of the replies are from the UK
AMC-FCL1.380 includes the JAA ME CRI syllabus. Under the heading Minimum Control Speeds it states:
The purpose of the exercise is to demonstrate that the aircraft is more controllable with the failed engine simulated feathered, and with 5 degrees of bank towards the live engine. in other words to equip the student with sufficient knowledge to be able to deal with the worst case.
The Instructor should fly the aeroplane, whilst the student experiences the differences in rudder force under each condition.
AMC-FCL1.380 includes the JAA ME CRI syllabus. Under the heading Minimum Control Speeds it states:
NOTE: This exercise is concerned with the ultimate boundaries of controllability in various conditions that a student can reach in a steady asymmetric power state, approached by a gradual speed reduction. Sudden and complete failure should not be given at the Flight Manual Vmca. The purpose of the exercise is to continue the gradual introduction of a student to control an aeroplane in asymmetric power flight during extreme critical conditions. It is not a demonstration of Vmca.
The Instructor should fly the aeroplane, whilst the student experiences the differences in rudder force under each condition.
The Instructor should fly the aeroplane, whilst the student experiences the differences in rudder force under each condition.
The stude needs as much hands-on as possible; why do you think they can't fly the sequence I described earlier (18/May)?
Added later:
apologies Whopity, on reflection my comments seem aggressive and that wasn't the intention - it was late
Splitting the handling is always difficult; I agree that it's useful for the stude to concentrate on the rudder pressures during the teaching of the effect of power and speed during asymm1 but not during the Vmc work in asymm2 because they need to have experience of how the aircraft feels. HFD
Last edited by hugh flung_dung; 30th May 2006 at 10:15.
Hugh - you clearly do not understand the purpose of this element of the MEP syllabus. I would strongly suggest that you seek some remedial training before you kill yourself and/or one of your students,
Join Date: May 2006
Location: Australia
Posts: 28
Likes: 0
Received 0 Likes
on
0 Posts
Black gun
Does it really matter which country we are training in, is it not the purpose of instructors to train students to be safe and efficent pilots?
I have not done intially twin training for a few years but I used to demonstrate Vmca by locking the rudder at say Vmca +10 and put a lot of emphasis on recognising and recovery.I am now a check and training captain for a large company on turbine engined aircraft and on intial endorsment on type I still do the same.
This is a good diccussion, it is upto us in the industry to discuss with the local CAA, FAA or which ever body we fall under our concerns in order to improve safety.I have heard people say they are not approachable, you will be suprised.
I have not done intially twin training for a few years but I used to demonstrate Vmca by locking the rudder at say Vmca +10 and put a lot of emphasis on recognising and recovery.I am now a check and training captain for a large company on turbine engined aircraft and on intial endorsment on type I still do the same.
This is a good diccussion, it is upto us in the industry to discuss with the local CAA, FAA or which ever body we fall under our concerns in order to improve safety.I have heard people say they are not approachable, you will be suprised.
Join Date: Apr 2006
Location: Ho Chi Minh City Vietnam
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Vmca...ME instruction
Gentlemen,
It's been many years since I instructed in light twins...even longer since my initial flight instructor check ride. In turbine equipment, we don't do Vmca demonstrations. (Never saw it in any airline's syllabus.)
However, in the U.S. it used to be required for the checkride for the multi-engine applicant to demonstrate Vmca, as it was also required for the instructor applicant to demonstrate the ability to teach Vmca (both in the classroom and in the airplane). Additionally, for the instuctor applicant, it was also required to demonstrate the knowledge of how not to you kill yourself and the student during such instruction.
The problem is stall speed and Vmca. If Vmca is well above the stall speed, the aircraft will roll before it stalls...and recovery is intuitive and conventional. If the stall speed is well above Vmca, the aircraft will stall before it rolls, and (assuming you have coordinated flight), recovery is, again, a 'normal' stall recovery exercise.
If the two speeds (for the conditons you have at hand) are close to or equal, you will surely spin. In most light twins, this means death to all on board, as spin recovery in light twins is difficult...as John says...better left to the test pilots.
We all know what affects stall speed...what increases it, what decreases it. And, we know what affects Vmca. It's up to the instructor to 'adjust' these variables to ensure the two speeds are not close or equal to eachother. And, all this should be briefed with the student prior to the flight.
In my humble opinion, it is important for the student to know how to handle a Vmca situation...what causes it, what to do to recover...how the aircraft 'feels', etc. This goes along with the demonstration of how Vyse and Vxse vary with weight altitude, bank angle, etc...how Vmca varies with engine power output, CG...et. al. All this is necessary for the student to be 'the master of the aircraft' (as, ultimately, the FAA wants to see on check rides).
Tom
It's been many years since I instructed in light twins...even longer since my initial flight instructor check ride. In turbine equipment, we don't do Vmca demonstrations. (Never saw it in any airline's syllabus.)
However, in the U.S. it used to be required for the checkride for the multi-engine applicant to demonstrate Vmca, as it was also required for the instructor applicant to demonstrate the ability to teach Vmca (both in the classroom and in the airplane). Additionally, for the instuctor applicant, it was also required to demonstrate the knowledge of how not to you kill yourself and the student during such instruction.
The problem is stall speed and Vmca. If Vmca is well above the stall speed, the aircraft will roll before it stalls...and recovery is intuitive and conventional. If the stall speed is well above Vmca, the aircraft will stall before it rolls, and (assuming you have coordinated flight), recovery is, again, a 'normal' stall recovery exercise.
If the two speeds (for the conditons you have at hand) are close to or equal, you will surely spin. In most light twins, this means death to all on board, as spin recovery in light twins is difficult...as John says...better left to the test pilots.
We all know what affects stall speed...what increases it, what decreases it. And, we know what affects Vmca. It's up to the instructor to 'adjust' these variables to ensure the two speeds are not close or equal to eachother. And, all this should be briefed with the student prior to the flight.
In my humble opinion, it is important for the student to know how to handle a Vmca situation...what causes it, what to do to recover...how the aircraft 'feels', etc. This goes along with the demonstration of how Vyse and Vxse vary with weight altitude, bank angle, etc...how Vmca varies with engine power output, CG...et. al. All this is necessary for the student to be 'the master of the aircraft' (as, ultimately, the FAA wants to see on check rides).
Tom
Join Date: Jul 2003
Location: uk
Posts: 1,042
Likes: 0
Received 0 Likes
on
0 Posts
Going back to thread starter, sounded like the aircraft was at such a high altitude it stalled before or at Vmca.
I was taught to demo/practise this at 2000 feet amsl.
Never had any problems with students having a go.
Up to instructor to know how do these manouvres.
I was taught to demo/practise this at 2000 feet amsl.
Never had any problems with students having a go.
Up to instructor to know how do these manouvres.
Join Date: Apr 2006
Location: Ho Chi Minh City Vietnam
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Vmca Demonstrations
BigEndBob is correct....At that altitude (2000 feet), Vmca should normally be well above the stall speed. Safe, but still effective instruction!!!
Tom
Tom
Join Date: Jun 2001
Location: Australia
Posts: 889
Likes: 0
Received 0 Likes
on
0 Posts
Up to instructor to know how do these manouvres.
I remain unconvinced though that the training actually does any good. How many ME pilots would respond well to a real Vmc situation outside the context of a briefed lesson?
O8
Join Date: Jul 2003
Location: uk
Posts: 1,042
Likes: 0
Received 0 Likes
on
0 Posts
Engine failure at Vmca potential killer..its the risk we take...be it small for the greater safety in other areas.
For instance what would happen if one engine failed during power on stall practise...doesn't bare thinking about..but we continue to do power on stalls, even if we recover at stall warn/buffet.
Vmca demonstration practise is useful so that student can apprieciate the rudder loads and technique required to control aircraft at the critical phase between Vmca and blue line, which we practise at altitude.
Hopefully in real situation the student may be able to land ahead and not cartwheel the aircraft across the airfield.
Does any student remember much after training for any emergency, its up to instructors to be inventive on checkouts and go through emergencies rather than just swan about the sky.
Get student/pilot to state the emergency actions before takeoff.
As for engine failure on runways, i've always pulled the mixture, let the aircraft get a bit of forward speed, its easier to keep straight.
For instance what would happen if one engine failed during power on stall practise...doesn't bare thinking about..but we continue to do power on stalls, even if we recover at stall warn/buffet.
Vmca demonstration practise is useful so that student can apprieciate the rudder loads and technique required to control aircraft at the critical phase between Vmca and blue line, which we practise at altitude.
Hopefully in real situation the student may be able to land ahead and not cartwheel the aircraft across the airfield.
Does any student remember much after training for any emergency, its up to instructors to be inventive on checkouts and go through emergencies rather than just swan about the sky.
Get student/pilot to state the emergency actions before takeoff.
As for engine failure on runways, i've always pulled the mixture, let the aircraft get a bit of forward speed, its easier to keep straight.
BillieBob:
If you bother to refer back to my referenced post on 18/May you will find:
What exactly didn't you like about this?
HFD
If you bother to refer back to my referenced post on 18/May you will find:
Vmca is the min dynamic "recover and maintain S&L constant speed" speed for sudden complete failure with gear up and everything else in t/off position - there's no requirement to even demo this in the UK.
All control demos are steady state:
1. start at Vyse, gradually throttle back an engine, slow down until a control reaches a limit or Vs+5 reached. Recover by retarding live and lowering the nose before throttling-up both
2. as above but at zero thrust
3. as above with gear and flap
4. as above but at 3-5 deg of bank to live
The only dynamic demos are done well above Vmca: initial failure demo, EFATO, Vtoss.
IMHO fooling around with dynamic failures near to Vmca is asking for trouble and accomplishing nothing -especially if the aircraft is allowed to stall, which must have happened in the situation cited by Centaurus.
All control demos are steady state:
1. start at Vyse, gradually throttle back an engine, slow down until a control reaches a limit or Vs+5 reached. Recover by retarding live and lowering the nose before throttling-up both
2. as above but at zero thrust
3. as above with gear and flap
4. as above but at 3-5 deg of bank to live
The only dynamic demos are done well above Vmca: initial failure demo, EFATO, Vtoss.
IMHO fooling around with dynamic failures near to Vmca is asking for trouble and accomplishing nothing -especially if the aircraft is allowed to stall, which must have happened in the situation cited by Centaurus.
HFD
Join Date: Feb 2004
Location: Alpha Quadrant
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
MEP EFATO & Take off roll
In the UK MEP syllabus we are not required to fail an engine on the take-off roll, only brief it and any EFATO must be done at a minimum of 500 AGL. 
CY&B
Mustve miss heard him.....Ohh well...........
CY&B
Mustve miss heard him.....Ohh well...........
Last edited by CaptYanknBank; 6th Jun 2006 at 23:36.
Moderator
Join Date: Mar 2003
Location: Orlando, Florida
Age: 68
Posts: 2,586
Likes: 0
Received 0 Likes
on
0 Posts
C Y B - I have a suspicion that that is a company rule - not CAA.
On test (at least on CPL) the candidate is required to DEMONSTRATE a rejected take-off on command (before Vr).
EFATO - usually in the region of 250<300 agl (i.e. before power reduction).
On test (at least on CPL) the candidate is required to DEMONSTRATE a rejected take-off on command (before Vr).
EFATO - usually in the region of 250<300 agl (i.e. before power reduction).
CY&B:
Agreed, but the test includes a "rejected take-off"; some people (not me!) supposedly interpret this as being from an engine failure.
Can anyone explain the purpose of a practice rejected take-off on a test?
HFD
Agreed, but the test includes a "rejected take-off"; some people (not me!) supposedly interpret this as being from an engine failure.
Can anyone explain the purpose of a practice rejected take-off on a test?
HFD
Join Date: Feb 2004
Location: Alpha Quadrant
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
UK CAA MEP RTO & EFATO
Just spoke with CFI ohh fountain of all knowledge.......
UK CAA MEP RTO not trained or tested, briefed only.
EFATO must be trained and tested above 500 AGL.
CY&B
UK CAA MEP RTO not trained or tested, briefed only.
EFATO must be trained and tested above 500 AGL.
CY&B
Last edited by CaptYanknBank; 1st Jun 2006 at 14:46.
CY&B:
Would you ask your tame fountain how he/she deals with item 5.1 (RTO) here:
http://www.caa.co.uk/docs/33/FORSRG1157.pdf
I confess that I ask candidates about RTO but don't test, despite it being listed as a mandatory test item. IMHO testing RTO would add cost/risk/stress for no benefit - but I'm willing to be convinced otherwise.
HFD
Would you ask your tame fountain how he/she deals with item 5.1 (RTO) here:
http://www.caa.co.uk/docs/33/FORSRG1157.pdf
I confess that I ask candidates about RTO but don't test, despite it being listed as a mandatory test item. IMHO testing RTO would add cost/risk/stress for no benefit - but I'm willing to be convinced otherwise.
HFD