"Light Twin" fatal at Hawarden

[Miserlou]

MJ,
My point is not about the magic of Perf A but the folly about a max 5 degree banked turn in the engine failure situation.

I hoped to get over the point that lowering the nose and aiming for the correct speed (for therein lies the magic) rather than farting around trying to avoid a critical speed is the far safer mindset. And having achieved Vyse, manouvering should not be a problem.

Having achieved Vyse one can assess the performance available and begin to examine your options. Before that time nothing else matters.

[mad_jock]

And having achieved Vyse, manouvering should not be a problem.

That's is completely wrong. And fundamentally shows you don't understand Vmca.

[Pace]

So much comes down to energy management and control forces. When I was involved in developing a MSFS flight model I took measurements in a Seneca to try and get better flight dynamics and control feel in a gamey MSFS.
Trimmed in the cruise 1/2 inch deflection on the yoke was required with quite a force to pitch the aircraft 10 degrees.
We all know at just above the stall on landing the column will come back several inches to its stops and to almost its maximum deflection.
the same goes with the rudder the faster you go the less movement of the rudder for a given effect the slower you go the more movement is required for a given effect until there is no more rudder movement available for a desired effect!

We have two energy sources to tap into! From the engines and from the potential energy in the airframe.
with any minimal performance aircraft whether it be a single or twin the less energy source available from the engines the more pilots are reqired to tap into the potential energy in the airframe by pitching for energy or speed.

Hence the old argument of pitching for speed or power for speed. Low time pilots are taught to pitch for speed in low powered draggy aircraft.
neither argument is correct as you have two throttles one to the engine/s and one to the airframe in the form of a column and it is a blending of the two sources not one which maybe required.

What has this got to do with VMCA and engine out on twins? Quite a lot really.
VMCA is literally the point like the elevator where the speed of air over the surface of the rudder is so slow that maximum rudder movement is required for a given effect.IE to counteract the effects of asymmetric power from one side of the aircraft only.

In this case to counteract the effects of unequal power from one engine rather than two. In that situation there are only two choices increase the speed i.e. pitch for it or reduce the power from the live engine or bank against those forces to reduce the requirement for rudder.

but banking brings its own problems especially in a minimal power (engine out in a twin)
We all know what happens if you take a 150 and go into a 45 degree level bank maintaining altitude without adding power from a low power setting?

so for me its all about energy management especially like in draggy low powered singles where you need to pitch for potential energy in the airframe.
The Twin engine out is the same, a low powered draggy aircraft where the pilot needs to tap into the airframe potential energy more and not get into high drag situations.

Hence why I see light twins as minimal performance aircraft especially engine out and why far greater lateral thinking needs to come into the equation rather than climb at all costs at blue line. That is great if the pilot can peg blue line regardless of a climb level flight or descent but sadly few rarely do.

Pace

[rustle]

Pace, there are far too many occurrences within this tread for me to quote each one, however you keep on about

That is great if the pilot can peg blue line regardless of a climb level flight or descent but sadly few rarely do.

Very bad accident and fatality statistics on loosing an engine

[sic]

but I cannot find any statistics to back this up.

In fact, if we were to even consider your comment for a moment we would expect to see far more ME aircraft appearing in the AAIB bulletins each month as every MEP training flight, exam and renewal; every [ME]IR training flight, exam or renewal, contains a considerable element of asymmetric flight, EFATO (possibly at 200') etc.

But they aren't.

...and to take this consideration even further...

Does this mean lots of instructors or examiners (including CAAFU examiners) are signing people off who cannot hold blueline (Vyse)?

That these same examiners are actually having to take control but *still* signing people off?

Hell of a supposition!

The records are not bulging with MEP fatalities, they are 'news' because they are very rare events.

Sensible discussion about Vmca, blueline, banking-to-live etc all very good, useful discussion

Dubious "statistics" don't help anyone except headline writers or Russell Brand and, when I last checked, we ain't either...

[Miserlou]

MJ.
Check your dictionary as to the definition of 'should'.

I say 'should' because you 'may' encounter reduced control authority, especially rolling towards the live engine.

As PACE wrote the emphasis 'should' be on energy management. However, blue line is the magic speed in terms of best lift/drag ratio performance. But one should not be focussed on actually climbing: that may not be possible.

Rustle,
I suspect that that is not the case. Just that the initial learning has not become automatic and proficiency is not maintained.
That is where i came in on the thread, the SEP stall/spin accident rate is also rather poor.

[Pace]

Rustle

Fatal accident rate single engined aeroplanes: 0.31 per 100,000 hours.
Fatal accident rate multi-engined aeroplanes: 0.98 per 100,000 hours.
(Note that a fatal accident for the purpose of the rate above is an accident in which there was at least one fatality. It does not reflect total people killed)
Total accident rates were similar at 9.54 per 100,000 hours for singles and 8.39 per 100,000 hours for multis. The difference is that accidents in multi-engined aeroplanes were around 3 times more likely to result in a fatality.
Total reported hours flown were 1,299,900 for singles, and 2,647,300 for multis.

historically in engine failure accidents you were more likely to be killed in a twin engine than single (maybe that has changed)

Pace

[mad_jock]

Nope you still don`t get it. There is nothing reduced about a Vmca incident. Its total uncontrollable aircraft. Until you reduce power on the good engine.

The handling up to thst point will be nothing different until you run out of rudder.

But crack on with your more than 5 bank i won`t be on board and it will give us something to talk about for a couple of weeks afterwards.

[Fuji Abound]

Yes, very much my point. In the UK at any rate I think the vast majority of twin pilots are well trained, and I think the frequency of the re-currency check goes a long way to help keep these skills current. Of course a low hours twin pilot, particularly one not current, and in difficult conditions, will find an unexpected engine failure at a critical flight phase challenging, BUT in many twins it really isnt the event it is made out to be.

As to the stats., as ever, they cant be taken in isolation. We have well rehearsed the accident stats for the Cirrus in the past. Yes, it was higher than most light singles for some time. Yes, pilots used the Cirrus to fly further, higher, and in more challenging conditions than many other like singles. Twins are the same. Pilots use twins to fly further and in more challenging conditions, and they are more complex, you are simply not comparing like with like.

[Miserlou]

MJ.
You're not making any sense. Tell me please, how are you maintaining 5 degrees of bank into the live engine?
With aileron? Thought so. So there is more aileron available (control deflection) away from the live engine than into it. Thus, reduced authority to the live side. I think you'll find it rolls quicker to away from the live engine too.

I have, in 25 years of flying NEVER heard anyone advocate limiting turning bank angle to 5 degrees in an engine out situation.
I have however, heard much discussion of whether it is best to turn into or away from the live engine if there is a choice.

[Pace]

Fuji

The thread was about a very sad and tragic light twin accident with an experienced pilot at the controls!

The aircraft dived vertically into the ground here in the UK killing both occupants!

Barring some unlikely but possible catastrophic failure usually all these accidents come back to pilot error.

As I stated earlier in the thread I have now lost several friends in flying accidents 4 of which were better pilots than I am so we have to look at why or what can be learnt or improved to stop such things happening to some of us in the future.

it is easy to bury ones head in the sand and state that all in the garden is wonderful but it obviously is not!

I have over 3000 hrs in a variety of piston twins in every bit of **** you could imagine and on numerous occasions you could be talking about me but for luck or whatever I am still here ? I am not portraying myself as some sort of know it all Sky God far from it!!

Now flying Jets exclusively albeit a variety of Slowtations the single engine performance is as different as chalk and cheese and light twins are a unique breed which should have unique training in dealing with them rather than training directed at high performance machine like I fly now!

Personally I do not think a paltry 5 hours practicing climbing at blue line is adequate i STRESS THE WORD CLIMBING (many want 10 hrs to convert to a single engine Cirrus)!

With that its better I shut up


Pace

[Fuji Abound]

Pace as always you make a good point.

However, lest we forget this is GA. Of course in an ideal world every pilot would have a work out in the sim every six months, but its not possible. GA is fragile enough as is. So we must balance risk with reward.

I have said before give 10 pilots a PFL and 8 will not perform well, but the majority would survive were it for real. Most pilots flying twins will survive an engine failure, may be about the same number as will survive a tyre blowing at 70 mph on the motorway, but at least pilots are trained to deal with the emergency better than motorists.

So as always there are choices to be made. Increase the training significantly and there will be almost no private pilots left flying twins. Strangely in a "bad" accident year the fatality rate might actually be higher because the population is so small.

No, I think the risk reward analysis is about right. Of course the bar should be higher for commercial ops. - who ever said trust the average GA pilot with your life .

Ps I have a go at a few engine failures about every six months. If they arent up to standard I do some more and I know my instructor would insist if I didnt. Actually I think most instructors are pretty aware of the responsibility they have in letting loose a twin rated pilot, and on the whole do a pretty good job. Of course potentially the dangerous pilot is the one flying almost no hours between renewals who sets off in the 11 month and his luck runs out. However fortunately we are still asked to accept some element of personal responsibility. Inevitability some exbit less and fall into the low time high risk category.

[F900 Ex]

I do believe there is an amount of confusion here as to exactly what Vmca is.

It is a minimum IAS airspeed in the air given a defined set of conditions of which one is using 5 deg of bank towards the live engine in light multi engine aircraft, below this speed loss of directional control will occur, this is a certification speed.

The same applies to jets however the 5 degrees of bank is not as relevant given there is no aerodynamic critical propellor and there is usually a far greater excess of thrust for climb performance.

There are many factors that will increase this minimum Vmca IAS. Turning the aircraft into or away from the live engine for manoeuvring purposes has nothing to do with using 5 degrees of bank for Vmca certification as you should not be flying close to Vmca during normal operations either using 2 engines or with one failed in a light multi engine aircraft.

For manoeuvring purposes then use the recommend figures from your AFM.

[mad_jock]

There is no difference between the different propulsion devices. apart from with props we have feathered and un-feathered to add to our list of variables.

The is the plane climbing or descending is just a function of excess power.

You just need to think of the aircraft with a force out to the side with an opposing force countering it at the tail.

Turning the aircraft into or away from the live engine for manoeuvring purposes has nothing to do with using 5 degrees of bank for Vmca certification as you should not be flying close to Vmca during normal operations either using 2 engines or with one failed in a light multi engine aircraft.

Well unfortunately it does and is what kills people turning onto final with one engine powered up and S&L. But according to the TP the reason for this in the main is the nursing of one engine to get them home and having a power setting on the bad one which is below zero thrust.

there was actually a video on here which I can't find of an aircraft flying towards an airport with audible farting of an engine. Then all of a sudden it just rolls on its back and 5 seconds later turns into a fire ball as it impacts.

As I said if there is no reason to do more than 5 degrees of bank ie hitting the ground etc try not to do it. But if you have to yes you can do it and just hope that your not going to have problems and be ready to reduce power on the good one as you come to the extreme of your rudder travel.

[Miserlou]

So are you saying rudder is what stops the aircraft rolling on its back below Vmca, Jock? Surely you mean aileron.

And just so as you understand the criteria for Vmca, it will be set at the point where the maximum force on either rudder or ailerons is reached. This may or may not be at full deflection.

In my long ago youth, I was taught (in a glider) final turn MINIMUM 30 degrees of bank. This is precisely to avoid stalling/spinning.

And it is exactly why your MAXIMUM 5 degree banked turns are dangerous.
If you are as hairy-arsed as you said a while back then I fear you are suffering from the over-conservatism which often afflicts the old. Over-conservatism to the point where it becomes dangerous.

[mad_jock]

I mean rudder its the only thing that stop the out of balance yaw from the live engine. Once you have no more force to oppose your into a spiral dive.

And unless you have one air brake up and one down I struggle to see how you can have Vmca issues in a glider.


The 5 degrees is only a limit unless other things preclude it when you on one engine not with normal ops with both donks working.

[dirkdj]

MJ,

Spiral dive is high-G, high speed, coordinated descending turn, not likely to be your problem near Vmca. Stall-spin is more like it. Different beast.

[Miserlou]

MJ,
It seems you have seriously misunderstood the dynamics of the situation.
The rudder is there to maintain directional control (secondary effect, yaw).
The ailerons controls roll (secondary effect, roll).

In the 'max power below Vmca' case it is the roll which is uncontrollable.

Gliding relevance? Well, apart from that I have yet to fly a type which doesn't fly the same way, not banking more than 5 degrees brings you closer to a more critical situation.

Dirk,
I suggest it is just loss of control. May also result in stall or spin of course.

[Pace]

And the biggest rule of all

Keep the bloody thing flyiing !! far better to crash under control that fall out of the sky like a stone!Do not fixate on having to climb at all cost and do not forget the 3 rd engine in twins or the 2nd engine in singles i.e. shove the nose over and trade altitude for energy

Pace

[Fuji Abound]

It is certainly true whether it be a single, twin or I guess even more engines, never give up on keep the thing flying. The one thing that has always impressed me when reading the accident reports is even if you plough through the odd roof, hedge and fence as long as you have remained in control and not allowed the aircraft to stall you have a reasonable to good chance of walking away.

- unless of course you fly a Cirrus (for Pace's benefit).

[Pace]

fuji

I am going to rent time on a Cirrus for next year really miss the private piston flying so after Christmas will look at the best deal i can get

Pace