Cessna 340 - lookin' for advice...
 

I've posted this on D&G, my usual hangout, but throught I might trawl here too, just in case...


OK, so I done gone and done it again. Bought another toy. (Reckon I'll get my internet disconnected after this :) A very nice Cessna 340 is being added to the fleet, initially in the US, and then back to NZ. Yes,it checks out very well mechanically, and yes, it's very well priced, given the twin market. I know there's a lot of wisdom here, so thought I'd ask if anyone knows much about these questions:

1. Short field ops. I know, I know - it's not possible, per se, and it's sure not a short field machine. Still. Anyone know what the shortest possible/reasonable/safe takeoff would be for a 340 operating at very low weights? Say, 2 people and 40 gallons/250 pounds fuel. Published take off is 1600 feet or so, but that's at full gross, without VGs, and (I think) involves waiting till the machine is at 90 knots or so before rotating. Anyone with real world experience able to answer this one? A related query is:

2. If you take off at the slowest possible speed, in a fairly powerful twin, is it true that a catastrophic engine failure means you could get into a VMC roll even if you had perfect reactions, in terms of pulling both throttles and applying full opposite rudder? A very experienced instructor and friend of mine says this is the case. He has a lot more experience than me, but still, I'm surprised. I'm willing to "pull the other one" and accept whatever I get if I have a low speed engine failure on take off, but was surprised to hear that no matter what, I'll be heading into the trees upside down. What do you guys think? Is my instructor friend correct?

3. Training. Amongst other machines, my current twin is an old Aztec. The 340 is, of course, a big step up. I can and probably will train in the US. Is Flight Safety (Kansas/Long Beach) overkill? What's a sensible expectation re syllabus and training time for the transition? I'm not looking for shortcuts here...but I'm only VFR, and I wonder if FS's training is skewed too much to IFR?

4. Getting her down to NZ. Am thinking, to be conservative, that the wisest thing to do is take the wings off and pack her into a 40 foot container. Anyone know a. how much of a big deal it is to de-wing & pack such a big aircraft (is it even possible??) and b. contacts for 40 foot containers & shipping from US to NZ?? Of course, a good contact for shipping US to Oz would be fine, cos I'm sure they can get a big box to our little country too...

Any help and all thoughts would be welcome. If anything I've said sounds dumb, well, I guess I'll find out soon enough - but would appreciate the thoughts of them what know...

In a twin rotation speed should not be below Vmc, therefore:

1. A short field take off in a twin is limited by the acceleration to Vmc ( plus safety margin, usually +5kts or even +10kts)
In a single the shortest possible take-off is actually a combination between the soft field T/O technique and the short field T/O technique.
You can't (shouldn't) do this in a twin. It will lead to lift-off below Vmc.
So the ground roll in a twin is affected by:
-weight
-density altitude (if non turbo)
-runway surface ( dirt, gravel, grass or concrete)
-runway slope.

2. YES.
The definition of Vmc under FAR 23 :

".........critical engine suddenly inoperative with the working engine at maximum rated T/O power in T/O configuration (=gear up)"

Flight controls really work based on a very simple principle:
airflow x deflection= effect
Since airflow is speed it means speed x deflection= effect.
Vmc is an aerodynamic control speed.
So at a speed below Vmc you have no (or insufficient) aerodynamic means to maintain control. So you will end up in the trees upside down.
It doesn't even have to be that dramatic, at very low altitude like 20'-30' you don't need a whole lot of bank to get the wingtip to strike and the aircraft will cartwheel. It doesn't need to roll upside down to end up in a heap.


3. I'm sure Flight Safety has a VFR only course, or if not they should be able to adapt the course they have. Simply swap the IFR training flights for extra VFR.

4. Be tempting to fly it with a very experienced ferry pilot.

Your answer, B2N2
 

Thanks for this. I think you're right, about ferrying v crating, and will do it that way. One fella on D&G pointed out the same thing - AND volunteered to help with the ferrying!

Re VMC, I want to be clear about the fact that this is NOT an argument - I just want to learn, so please do consider my question in that context. (I've seen too many Q's on Pprune deteriorate into e-yelling matches, and that's not where I'm coming from - I'm in no way an expert on twin ops, and don't know enough to authoritatively start an argument anyway :) So, my further Q is:

Yes, I understand the definition of VMC. I also understand why trying to continue to fly below VMC is likely to result in some version of the scenarios you've outlined. What I don't understand is why, if you were hair-triggered to cut power on the live engine, as close as humanly possible, as well as applying immediate opposite rudder (aileron?), then wouldn't the removal of the live power remove the roll/yaw immediately, and thus turn it into a common-or-garden engine failure situation? (I know, more speed and intertia than a single, so less survivable, but still much more survivable than going in w/o wings level...) ?

Also, a minor addition - I understand the effect of the after market VG kit, which is fitted to this aircraft, is to reduce VMC to very close to VS. Does that make a difference?

Your thoughts welcomed.

First of all you will find you can not fit a C340 in a container without cutting it up. Main problem is the engine mounts to end of Nacelle is over 8 feet 6 inches so it will not fit in a tall container. Over sized shipping is very costly and would be deck cargo getting into all kinds of corrosion issues. So a ferry flight is in your future.

Get Vortex Generators....they lower the VMC by 11 knots on a C340 to 71 knots....plus you get a 300lb gross weight increase.

Short feild takeoffs at low weights are not an issue. We frequently depart from 1600 foot feilds and rotate in about 800 to 900 feet. Yank it off at 80 knots and then put the nose right down to build speed to 100+. Of course if an engine does fail at or right after rotation be prepared to close both throttles quickly if it starts to roll. VMC demos with gear down and 15% flaps show resonable control until 70 knots. But I do believe it would not be the same under a take off situation.

Now landing in 1600 feet can be an issue. If we are not under 85 knots and are not going to touch down in the first 100 feet we go around. If you are under 85 knots and touch down early you can stop in 1400 feet provided your technique is good and you plant it on with no float. We use a slightly high sink rate, 600-700 ft and try to hit in a three point and push the nose over on touch down. Then max braking when able. Hard not to lock up the brakes until under 40 knots.

Great airplanes, shame what is happening to their values.....

The 340 - container from US - NZ still req'd. Anyone know?
 

Slatch, thanks for this. Yep, I've come to the same conclusion re ferry flights. I'll fly it around the US for a long time first, to be sure of the machine, and spend a year planning it, find a highly experienced person to take with me, then I guess it's the Big Blue for me :)

Thank you very much for the real world info - I appreciate it. I do, in fact, have VGs fitted, so I guess VMC is below VSO. Hopefully my machine will have similar performance to yours. Is yours the 310 hp model?

And whereabouts in CA are you? I'll be over there late this month/early Ma to pick up the 340 in Fresno, and will be flying all round the place, particularly anywhere b/w LA & the Bay Area. You obviously know a bit about real world 340 ops. As a new 340 pilot, I'd love to buy you lunch and pick your brains, if you'd be avail. No offence taken if not - maybe PM me either way?

B2N2, I'm still interested in your response, if you feel like it.

Cheers

Lostpianoplayer, fantastic screen name by the way.
I know too little about 340's to get involved in the short field discussion.
Engine out scenarios at some point always end up in a very gray area.

A twin is only truly different from a single if you respect it's virtues and vices.
The second engine is only able to do you any good if you stay in a fairly abstract performance envelope.
I am currently in a job where we rotate at Vmc +5, climb at Vyse+5 and we do not allow operations from runways less then ASDR.

Having said that, here is the flip side of the coin. Probably some arguments that you are familiar with.
The engines don't know if you are flying over water. The engines don't know that you are flying at night. The engines don't know that you are attempting a very short field T/O.
Outside the above mentioned envelope you are essentially flying a single since the second engine will not do you any good. But then, most of us have several thousand hours flying in a single. We do not hesitate to fly at night, over water or take-off from a very short field.
So is it unwise to explore the envelope of a twin and operate outside of it?
Not necessarily. There are certain area's of the world where this is done on a daily basis. Alaska, Afrika, remote regions of SE Asia.
Here's a great example:
http://www.youtube.com/watch?v=Mhp0jbTpUGM
You just need to be very aware that if things go pear shaped, the chances of walking away diminish compared to a single.
No only weight and inertia is an issue, a medium sized twin can carry heaps of fuel and what I really dislike about light and medium twins is the awkward entry and exit for the pilot. No door on the pilot's side or you have to work your way through the cabin to get to a door. I have absolutely no statistics to back this up but gut-feeling would tell me that survival rates would go up if some more convenient exits were provided. some of the "bad" examples:

P68 Partenavia, look at the location of the door;
http://www.airplane-pictures.net/ima...07-11/7954.jpg

Rockwell Aero Commander, pretty much same door location:
http://www.futura-dtp.dk/Flysiden/im...oCommander.jpg

One of the better ones, Twin Otter:

http://www.nefsc.noaa.gov/read/prots.../noaa%2057.jpg

Lets think about this
 

The Cessna 340 is a great plane. With RamVI’s and VG’s the published rotation speed is 91 kts with a climb out of 108 kts to safe altitude. To consider speeds below these is crazy. If an engine pukes on takeoff, forget the catlike reflexes and honed skills, get real. If you don’t value your life maybe you wife, child or passenger does. That 335 horse engine hanging on the right side is producing significant torque and is purpose built to roll you over if you are not prepared. It takes time, maybe four or five seconds to stop the fuel flow and actually stop producing power, not to mention the inertia that 2700 rpm of all that machinery spinning takes to slow down. It takes probably 2 rpm, or .000741 seconds with a busted crank to stop the inop engine. That 335 horsepower on the right wing can lift one hell of a lot of metal in 5 seconds without proper counter forces in an asymmetric engine out scenario.

Regarding runway length, I will not fly mine into anything less that 4,000 ft. Landing in 2,500 ft is no problem; however the engine out on takeoff scenario requires a few more considerations. To accelerate to rotation speed, liftoff, have an engine fail and land safely requires at least 2,700 feet for Sky King to do. So why push it, include a safety margin.

If the mission profile does not fit the 340, look at the Maule or the Caravan or other purpose designed short field aircraft. Don’t buy the 340 because you can get a great deal on one and make believe its got STOL capabilities.

B2N2, long time no see.

You can take the Twotter out of your list, there is a pilot side hatch (on all versions as far as I can remember). Take a quick peak at your last photo, you'll see the hinges just visible.
But from your post I'll take it you like the Aerostar concept, entry and exit are pilot side ONLY; I would hate to be stuck all the way on that back seat.
Gotta love planes build by pilots for pilots!
Take a look: Ted Smith-Aerostar 600

I have about 350 hours flying a VG equiped C340. I think it is the best combination of speed, wx capability, comfort, and economy in its class.... for operations from one IFR airport to another with a max of 4 people. "But" and sorry to be blunt, I think anybody who operates this airplane into a 1600 foot strip needs his head examined.:hmm: Yes it can be done but there would be absolutely no margin on either takeoff or landing.:{ Our SOP was a 3000 foot field as a min and every take off was 0 flap with a 100 knots rotation speed(blueline on a VG machine) with selecton of the gear to up as the decision point (i.e. with gear down both throttles must be closed and you take your lumps straight ahead, with gear coming up takeoff is continued and engine failure handled as an in flight emerg)

Bottom line buy an Islander if you want to go into the really short strips.:ok:

Thx for thoughts
 

Been away or a few days, but yeah, Lifeisgood & BPF, I take your point(s). I haven't, in fact, done ANY flying in a 340, let alone off a short strip. So I'll have to save the head examination till I get the new beast and decide where to base it :) Nor am I here to argue, so, um, I won't! I'm just researching the question, at this stage, and comparing viewpoints. Particularly on the issue of why you can't just cut power immediately to prevent a VMC roll on takeoff.

There are a whole lot of reasons for why I'm asking this, and yes, I hear ya. I guess I wasn't suggesting catlike reflexes, so much as normal reflexes, but being wide awake to the possibilities of emergencies, as opposed to getting complacent. And, like it or not, there ARE differences in pilot abilities, currency and so on, so some minimum field lengths for commercial operators, for instance, have to be a minimium that works across the board. But I hear you guys, loud & clear. Thanks for the input.

One of the problems with training for the multirating is all engine failures are

1) expected, and

2) always total.

Unfortunarely the real world is rarely so accomadating. Many engine problems manifest themselves as engine surges ( can be intially difficult to detect as airplane yaws back and forth) or partial failures ( potentially leading to shutting down an engine producing power ) or prop under or overspeed. While in theory rotation below VMC followed by engine failure can be survived by instantly reducing power on the operating engine, I would suggest that in practice most pilots are going to wind up as a smoking hole in the side of the runway

By the way one of my pet peeves is frequent discussion on this forum about how pilots will evaluate the situation and then use their judgement to decide how to deal with an engine failure during takeoff. Airlines have a defined go no decision point with a set of unvarying actions before and after that point.

This came about after many crashes proved preprogrammed responses to these kind of emergencies was the most effective way to deal with an engine failure during the takeoff sequence. So what makes PPL's think they have more cognitive power to dal with a bad situation, than a 30000 hr airline pilot who will only utilize rote preprogrammed responses :confused:

Thar is why the owner and I adopted the proceedure I outline in my earlier post. It is the closest we could think of to duplicate the airline SOP.:ok:

No, Vmc is a certification value. The actual aerodynamic control speed varies with a number of factors, ranging from CG to density altitude, flap position, gear position, and gross weight.

A large part of this discussion (which really ought to be centered on the 340, rather than aerodynamics or procedures) has been about the ability or efficacy of preventing a Vmc roll following engine failure while taking off at speeds less than the minimum single engine control speed.

The airplane will not, as a rule, snap roll inverted and crash. Control may be lost faster than you think, however. Regardless, why would you want to find out? It seems the point of the questioning is to see if you can take off at a ridiculously slow speed and still manage to pull back both engines in time to prevent a roll. Rather than do that, how about using a longer runway and flying the airplane at a speed which does maintain control...and flying the airplane instead?

All too true. I've done an engineering type degree and my Pa was an engine designer. When an engine is just about to go t*ts up, it always seems to be running better than ever. Two stroke petrols deliver most power when just so weak they're about to seize. My Land Rover (recent toy) gets really nicely blippy on the throttle when it's about to run out of fuel (must re-time the injector pump).

Never underestimate the power of the buggers to bite you on the arse.

It 'can' be argued that twice the possibilities, four times the problems.

Pet peeves...
 

...and one of my pet peeves is the argumentative tone that things can take here on Pprune, so, I'm not going to argue. I'm here for education....

Re the parallels between airlines and private flying, I agree to a point, and particularly on the idea of pre-programmed responses to certain events. I try to emulate that approach as much as poss in my own flying. But let's not forget the airlines aim for - and achieve - FAR higher safety levels than we do, at a certain cost. If we were to aim for the same levels of safety, we would only ever fly out of balanced fields, we'd have a fully trained co-pilot on each flight, we'd have turbine engines with ample excess thrust so a serious climb rate is attainable on one engine, we'd have professional flight despatchers, and we'd have....er....an airline :)

But no, I don't maintain I have more cognitive power than experienced airline pilots. Just a much, much wider range of situations to assess, sometimes, and less SOPs. More privileges. More freedom. More risks.

At private level, therefore, we have the privilege of assessing and operating to our own levels of risk. So we don't, in fact, always fly out of balanced fields, we certainly can't climb out on one engine if we're flying a single and the engine quits, etc.

I'm asking about the concept of lifting off slow, and then if the engine fails, pulling the other one and accepting a controlled crash, cos I'm trying to work out whether I could or should operate into my own private strip. I fly a lot of single engine STOL Ops, (on a different field - my one is actually very long for a normal single engine aircraft) and I guess I can't really see the difference between flying off a short field in a single, and accepting that if the engine fails in the first 5-10 seconds after airborne you're in deep trouble, and doing the same in a twin. Double the engine failure risk, of course, but neglible + neglible = close to negligible, doesn't it? I'm guessing that we're talking about a 5 second period between rotation and a reasonable VMC-proof speed. Again, I'm NOT here to argue - I'm here to learn. And nor am I attached to doing so - I'm just trying to figure it out. But that's the context, and the reason I'm asking...

Hey mate
 

Listen mate, put a sock in it.

The 340 with RamVI’s and VG’s has a published time from takeoff roll to 100 kts of 15 seconds at GTOW. The time frame from VMC speed to Blueline, which is VYSE (also 100 kts), is about 6 seconds. The most critical timeframe is those magical seconds when you are still earthbound and accelerating through the VMC speed and the wings are starting to fly. The problem is the little bugger wants to fly like a blooming pigeon. Around 75 to 80 kts the wings just come alive like Elton John in front of a grand piano. Your flight instructors have beat into you the need to keep the bird on the ground until the wind going over the rudder reaches at least 91 kts. They did this so that in the event one of the engines craps out there will be enough wind over the tail to give you a bloody chance of surviving the mess. Now if your nose wheel is still on the ground around this time (speeds from 70 kts to 90 kts) you will still have some directional control if you lose an engine. If you pull the nose wheel up to soon, say at 75 kts, and you then lose an engine, it would be arse over elbow mate. You see, the bloody wind would not be strong enough to give your rudder, that’s the tall thing sticking up at the rear of the aeroplane, enough counter force to offset the asymmetric force of a 335 hp engine four foot off your centerline trying to yaw the nose over to that ditch next to the runway. The safest thing to do is stick to the plan, published rotation speeds, balanced field length, plenty of recurrent training and a heavy dose of common sense. If you do all of these things your friends will think you are simply brilliant.

Heaven forbid that you seek for,or train to a high level of safety. You don't seek argument, and that's no argument. You have absolutely NO excuse for failing to seek the highest possible level of safety. Moreover, you have every responsibility to do so. That's your job description as PIC, in fact.

As a private pilot you hold more privilege than the holder of an ATP? Really?

No doubt from your questions and comments you take more risks. That's nothing of which to be proud.

You're asking the wrong question.

The real question should be what length runway you need to depart in order to achieve adequate takeoff speed and distance to enable safely handling the situation if an engine quits. If you're asking if you can handle one quitting while attempting to climb out or takeoff below Vmc, you're asking a stupid question. There really is such a thing as a stupid question. What you're really asking is "If I do something stupid, what are the chances that I'll be fast enough to save myself from my own stupidity?" Which of your instructors taught you to take off below Vmc?

Not that it's not possible to do by any means...but certainly the inexperience offered in the way you ask and your tone suggests that it's not something for you. Of course, you also sound like you intend to do as you please, without regard to what others may have to say.

What makes you think an airline must operate with a balanced field? A balanced field is one in which the accelerate go distance equals the accelerated stop distance, and this is very seldom the case. Rather, a rejection speed is computed which establishes a maximum speed to which the flight can accelerate before recognizing the problem and rejecting the takeoff. If the resulting stopping distance approximates the required takeoff distance, it's merely a coincidence.

You shouldn't be taking off, however, unless you have the ability to recognize the problem, and reject, and stop in the remaining runway, or stopway.

The issue of a first officer is largely one of aircraft certification and the regulations under which the flight is conducted. There's no question that in a highly complex, advanced aircraft, a SIC can be not only necessary, but immensely helpful. However, you make a poor comparison. Your aztec vs. a B747, for example. Consider also the complexity of operations, and the kindof flying you do may not require it. This does NOT mean you are excused from operating at the highest level of safety, and maintaining the highest level of proficiency. You have that full responsibility; operating privately does NOT excuse you from that.

Flight dispatchers are an operational requirement, and not all airlines use dispatchers. Some use flight followers, and not all of them are professionals. You, however, have the same responsibility in full to calculate your performance, know your fuel, your weather, your distances, your climb rates, and your capabilities before you go. Don't try to excuse yourself to a lesser level of safety merely because someone else isn't making the calculations for you. Moreover, regardless of who makes the calculations, the PIC is always responsible for them.

You don't need a turbine engine to act safely. Nor do you need it to assess takeoff performance or plan for it.

You could do that sub-Vmc takeoff in a turbine powered airplane and achieve the same results...if you're below Vmc, it won't matter if it's turbine or piston...pushing the power up will only aggravate your problem, and the fact is that your problems at that point are only compounded. So again, your comment really has no relevance to the conversation here, nor is it an excuse for acting unsafely.

I get the distinct impression that no matter how many people tell you not to go jumping into a higher performance airplane with a little more complexity, and taking it off Vmc, you're going to keep on asking until someone tells you it's okay. Anyone who doesn't is being "argumentative."

Therein lies the problem. You're already flying an aztec, you said. You shouldn't have to ask this question.

You're in deep trouble only if you fail to plan accordingly in the single. Your takeoff should be planned such that you already know where you're going to go and what you're going to do. You're going to be landing at a slower pace with far less mass energy, with a much lower stall speed, much lower touchdown speed, and better slow speed landing characteristics in the single; you can glide much more comfortably, farther, longer, and have none of the inherent dangerous characteristics that take place in the twin.

You may have no choice but to retard the good engine when a failure occurs in a light twin. It happens. However, especially in an airplane such as the 340, you should be planning your takeoff such that your weight, takeoff distance, and obstacle clearance area and departure area mean you don't have to. If you plan your takeoff by intentionally departing from such a short strip that you have zero options and your game plan is to put yourself in an emergency situation below the minimum control speed, then you've already decided to live a mistake before you ever start the engine. Starting with the fact that you've already placed yourself in a position where control may not even be possible.

Add to that the fact that aircrat such as the 310 and 340 use tip tanks with additional mass in the tip tanks and once a roll starts you may not be able to stop it.

There again is a big part of your problem. You're assuming, guessing. Your condemn the airline operation for it's high level of safety, which is a foolishly mind-blowing concept in it's own rite. However, safety need not be the purview of the airline pilot alone, nor the corporate pilot only...it needs to be yours. The difference between you and the professional pilot is that the professional pilot plans the takeoff with a failure in mind, not hoping that it doesn't. Forget professional...the responsible pilot plans in advance for each contingency, and thus plans for the safe outcome of the takeoff regardless of whether the engine fails or not. You don't need to be flying a transport category airplane to do that.

And to answer your question, negligible doesn't equal negligible. Your engine will either run, or it will not; that's a one out of two chance, and it doesn't get any better the longer you fly...or the more engines you carry. You have that opportunity every single takeoff, and had better be planning for it. Not just assuming it's such a slight risk it probably won't happen. When it does, in the twin you not only lose 80% of your available thrust, but the remaining value is fighting to take control away from you.

Strive to eliminate risk, not embrace it.

The problem is that unlike having a failure occur at a speed above Vmc where you have the luxury of losing airspeed all the way to the minimum control speed...when you lose the engine below Vmc, you can't accelerate to Vmc. Adding more power only aggravates the problem. That leaves you in a regime where your ONLY choice is to reduce power on the good engine because you have no more aerodynamic control authority. Often this speed occurs close to the stall speed, which will also be the case if you're attempting to depart from a very short field near minimum control speed...and you can get there in a big hurry as you slow when the first engine goes. You have to recognize and react to the situation (an inexperienced pilot will invariably attempt to push the power up, rather than retard it, and handle the directional control with aerodynamic controls alone), and then correctly apply reduction of power on the good engine.

In the meantime, you're applying opposite rudder to the failed engine, and opposite aileron. You're already slow, at a high angle of attack, and at maximum takeoff power. The lowered aileron on the side of the bad engine increases the local angle of attack, increases adverse yaw, increasing the effects of the failed engine, as well as potentially causing a stall along the section of wing occupied by the aileron. The yaw is made worse, the roll is made worse. As the wing starts down in the 340, additional rotational inertia is imparted to the fuel in the tip tanks, making the turn and the roll even harder to stop. Additionally, as the wing with the good engine still has airflow, local lift is created which isn't available on the side with the bad engine, increasing the roll. Further, as the yaw occurs, the wing with the good engine moves forward increasing lift, while the airflow over the retreating wing decreases lift, further aggravating the roll. Even if you pull the power, you may continue to roll once it's started. How far, how fast, really depends on some of the factors previously cited (including CG, flap position, gear position, weight, density altitude, etc. If you're near the ground at the time, you may not have to roll very far before you catch a wingtip, and you may be lacking the performance to climb much to avoid it. Your time to recover is further reduced.

Rather than find out when it's too late, don't put yourself in that position to begin with. You needn't be an airline pilot to be safe.

Thx everyone
 

OK. Enough things being taken out of context here to see this discussion isn't going anwhere. If it seriously seems as though I was "condemning" the safety culture of the airlines, or not trying to minimise risk myself, I guess I need to work on my writing skills -or qualify everything I say with so many modifiers & caveats that the meaning gets lost. But this isn't a legal thesis we're writing, it is, or was, an educational discussion, for me anyway. Ain't the anonymity of the internet wonderful? You can argue amongst yourselves. I'll think seriously about the issues raised in the thread though, and thanks to all, particularly the earlier posters who said what they had to say without the testosterone haze getting in the way. Sock duly placed. Seeya.

That's pretty much what I figured you'd say.

So far as out of context...you were quoted. Not taken out of context.

Some of you need to relax a little behind that keyboard.
...insert arrogance......
Not everybody is as experienced as "we" are.
...turn off arrogance...

There is no such thing as a stupid question, but there is such a thing as a stupid answer.
Why don't we simply try to answer and educate?

Good Morning
 

To SNS3GUPPY, very well said!

To B2N2, no arrogance intended, just concern that some soul was not listening to good advice. Line one of his post referred to looking for advice.

To Lostpianoplayer, flying a light twin like a 340 is a joy, please keep safety number one.

I for one enjoyed the exchange; conflict hones the skills and allows everyone to reassess their values and opinions. As pilots it is these values and opinions that dictate our actions, or lack of actions. If we do not express disapproval of an unsafe procedure, what kind of pilots are we?

(my bold)

Can you guys who assert this explain in terms of the aerodynamics why you believe a catastrophic engine failure at Vmc - 5 knots leads to more significant control problems in the air than on the ground, please?

Because...while still on the ground (nosewheel especially), more directional control is most times obtained (due to said nosewheel)...however, with many light twins, you might end up in that ditch off to the side of the runway anyway, unless you are jolly quick, and have quite good skills.
Even if throttles are closed, going off the end OR ending off to the side, is far better than finding oneself rolling inverted...with most times deadly results.

I'm not sure that directional control is guaranteed. Let's ask the Q on Tech Log where the certification folks hang out.

Ahhh, bookworm, you might read again what I stated originally.
Didn't say anything about 'guaranteed'.
And, I answered your question in Tech Log, with regard to 14CFR23 aeroplanes.

Training
 

Nothing is life is guaranteed, but proper training and understanding of Vso, Vmc, Vyse, accelerate-stop charts and other asymmetric forces are very important to safely fly a multi-engine aircraft. The pilots whom have taken time and responded to these questions have succinctly stated that Vmc is a critical factor in flight safety considerations. I have no dog in this hunt. However the author of this rant suggested taking a course at Flight Safety, I think the Kansas location handles the 340 training and you could not ask for a better solution to this question. The instructors at Flight Safety are very professional and have the ability to demonstrate in a simulator various scenarios. I wish I could be there to observe what will happen if someone attempts rotation at 70 kts and with gear down and has an engine fail. If you do this, please send me an email and let me get some friends together with a cooler of Bud Light, I’ve got a friend at F/S and I think we could observe. I suspect it would take about 5 seconds until either a cartwheel occurs or the AI is brown over blue. I am sure the trainers will be amused; they have a passion to “educate” us. Simulator training is a wonderful way to envisage in a secure environment what realities could occur in real world situations. One of my personal favorites is losing an engine in hard IFR, 600 ft ceilings, 30,000 ft tops, no GNS530 or GPS on board, 30 nm from destination and then have your remaining alternator fail. If you’ve never sweated in a 65 degree cockpit you will in the Sims. If the author does follow through with the Flight Safety training he might consider doing a Youtube video to publish this takeoff scenario for others to benefit from.

The simplest and best answer is get proper training.

I'm out of here.

Life is Good

And it wasn't my intention to contradict you in that, 411A. In essence, if you're saying that an engine failure at a critical time in the take-off can leave a 14CFR23 aeroplane "in the weeds" regardless of whether it's on the ground or in the air when the failure occurs, then I'd agree.

What I'm arguing is that, if that's true, there's no point in being precious about whether you rotate above or below Vmca. The decision is simple: if an engine failure occurs below Vmca, you close the throttles and do the best job you can, whether you're on the ground or in the air.

Bookworm, you really confuse the issue by taking it between multiple threads or forums. For others following along, the reference question in Tech Log is http://www.pprune.org/forums/showthr...highlight=Vmcg

You also are asking about different subject. In the tech log question, you asked about Vmcg, which is not the same as Vmca. One is minimum ground control speed, one is minimum control speed in the air; each have different criteria and requirements.

When 411a says that a part 23 airplane doesn't have gauranteed performance after takeoff, he's correct. This isn't at all the same thing as a Part 25 airplane, which does have certain performance "gaurantees" based on the nature of certification. For example, a multi engine airplane certificated under Part 23 isn't required to maintain altitiude after an engine failure, by virtue of it's certification, nor is it required to be able to go around on one engine, fly a missed approach with an engine failure, etc. Part 25 certificated aircraft are required to meet specific climb gradients following loss of an engine on takeoff (which translates to a go-around or missed approach, too). The Part 25 airplane has certain performance "gaurantees," whereas the Part 23 airplane does not.

You're getting confused between topics, when asking about Vmcg and Vmca.

An engine failure on the ground which occurs below Vmcg means that unless corrective action is taken, directional control of the aircraft is not possible. Full aerodynamic application of rudder will not correct for the loss of directional control. The loss will occur as lateral deviation from the centerline, or in other words, the aircraft takes off in a different direction. Vmcg calculation does not take into account the effects of nosewheel steering or differential braking. Vmcg is less than Vmca, and if during a takeoff a failure occurs prior to Vmcg, clearly one's option is to reject the takeoff, because directional control is no longer possible.

Vmca is another matter. The airplane doesn't simply turn left or right. For reasons previously provided in this thread, a rolling motion is imparted, and for reasons already given in this thread that rolling motion may not be stoppable or preventable...even if the power is pulled back. Particularly in an airplane such as the 340 where the tip tanks tend to exacerbate the problem of stopping any rolling motion once it's started, and particularly at low airspeeds when control authority is less. Particularly at low airspeeds when control authority is less, when one has elected to take off at speeds less than the minimum control speed. I think you see where that's headed.

On the ground, you may end up in the weeds if you don't act properly. In flight, you may end up in the weeds, upside down, on fire. You see the difference, perhaps.

So, you ask, what's the big deal taking off below single engine minimum control speed if you might have directional control problems before or after taking off?

Consider the alterantive, when acting prudently. One takes off at an airspeed which permits safe control of the airplane in the event of an engine failure. One is above Vmc, and has the luxury still maintaining control with appliation of rudder, banking into the good engine retracting flaps and gear, and climbing (where possible) at Vyse. When losing an engine after takeoff when below Vmca, one is gambling, and has no chance of climbing out. If one is very close to the stall speed, which is very possible, one may experience a very rapid loss of control with no chance of stopping the event. Add to that the fact that your first inclination in the event of an engine failure is to push the power up...not pull it back. This only makes things worse.

By taking off at a speed which permits full control, you have options. You also have time to act and react, configure, prepare for either a forced landing or a climb out at Vxse or Vyse, and to handle the problem. In other words, you're prepared.

Sad experience over many decades of multi engine training, testing, and flying has taught the industry these things. The FAA, for example, stopped allowing even engine failures on practical tests at any more than 40% of the takeoff speed, due to the number of accidents during practical tests for pilot certification, when performing a high speed rejected takeoff. That's even before the aircraft gets off the ground, when a loss of directional control is far less critical. Loss of directional control in the air, especially on takeoff, is about as critical as you can get.

A light twin may or may not be able to climb out on one engine. Whether it can or not, even if it's just holding altitude or maintaining control, it's far better than actually intentionally planning for a takeoff when there's no such possibility whatsoever.

The 340, depending on weight and density altitude, is capable of climbing (at a very reduced rate) on one engine. If one has planned one's takeoff properly, having remained on the ground until above Vmcg and taking off above Vmca, the option and ability is then available to clean up and fly off under control.

For airplanes which will not maintain altitude on one engine, one still has directional control in one's favor if one has properly elected to fly above Vmca, and one has a significantly improved ability to put the airplane on the ground under control, at a controlled rate of descent...as opposed to the original poster's plan of simply intending to yank the power back on the good engine and accept whatever lies beyond.

I don't know if the original poster has had occasion to arrive at an altitude of 30' or so above the runway on takeoff and suddenly retard power on one engine, then the other, and attempt to reach the ground...he doesn't appear to have had the experience of a real engine failure at all. Certainly not with one engine having failed while below Vmc, then while starting to yaw and subsequently roll (again, for reasons already explained in this thread), attempt to pull back the other engine and then land the aircraft...but you may rest assured that he doesn't want that experience. Nobody does. Even without the loss of control, attempting to suddenly lose power and then get that airplane to the ground is not at all the same as losing one's only engine in a single, and gliding. In fact, he's got a high probability of stalling it in the process. As well as doing it while yawing and rolling.

Think about it.

Bloody Hell but you gave him a thrashing. He’s no doubt in the bottom of his foxhole right now tending to his welts.

For God, Country and the Funny Acronym Association

At first I was worried that someone might actually be listening to what you are suggesting. Then I realized you are simply being argumentive, and that’s OK. I will also have faith that anyone that has a ME rating probably has a MEI and therefore has been trained by competent and knowledgeable CFI’s that teach solid aerodynamics principles (pardon the pun), safety practices and smart piloting techniques.

To that end I say, ask all the dim questions you want, assail us with foolish theories on rotation before Vmc, go ahead and run biofuel in you avgas engine.

In the words of Monty Python “I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! You mother was a hamster and your father smelt of elderberries!”

People should quote Python more often, lest we be blindsided by an exploding Scot, or attacked with fresh fruit,.

SNS3Guppy

In amongst what is undoubtedly good and thorough explanation, and also some rather patronising comments about what you think confuses me, is the central issue, which you put quite concisely.

The question, which I don't think you've answered yet, is why you think that on the ground you don't also end up "upside down and on fire". If the aerodynamic forces after an engine failure at that particular speed will roll the aircraft after its wheels have left the ground, why do you think that you will be spared if the wheels are still on the runway?

One possibility, put by 411A, is that the nosewheel offers a lateral force opposing the yaw and gives you a better chance of keeping the nose in front of the tail. But as I think we've now examined on Tech Log, no one seems to be able to come up with a certification requirement that suggests that the lateral force from the nosewheel will be available and sufficient to do so, even for a subpart 25 aircraft.

And that again, is pivotal. Once a subpart 25 aircraft has reached V1, which must be at least Vmca, there is that certification requirement that the aircraft can continue the takeoff. And because we rotate at or above V1, it's obvious that for such an aircraft we would never take it into the air below Vmca.

For a subpart 23 aircraft, the situation is different. Even after we take the aircraft into the air, we know that in the event of an engine failure we may simply have to do what we would do on the ground -- close both throttles and do the best job we can to keep it straight. If we fail to do that below Vmca, then of course we will "end up in the weeds, upside down, on fire". Even if we fail to do that above Vmca, there is a good chance we're still going to end up in the weeds and on fire because we don't have the performance to continue flight. Only when we reach a speed at which we know we can climb away on one engine (and I would choose Vyse) can we change the instinctive reaction to an engine failure and attempt to keep flying. Below that speed at which we would commit to flight, we close the throttles.

So for a subpart 23 aircraft, Vmca is not a useful speed at which to make that decision to commit to flight. It's usually way too low. Is it a useful speed to choose as a minimum for taking the aircraft into the air? Well the only reason it would be might be that there's a speed range below Vmca within which the aircraft is controllable on the ground but not in the air. And I'm waiting for you to explain why such a speed range should exist.

Actually, I did answer that, and hopefully this won't be too patronizing for you; READ!

An aircraft rolling along the ground doesn't mystically flip upside down, but an aircraft rolling out of control just after takeoff has no problem. You do see the difference, don't you?

Yes, on the ground, the ground is in the way. The hard surface under you. That ground. In flight, it's not in the way. One wing dropping on the ground in order to effect a roll isn't nearly the issue it might be in the air, owing to the wheel being on the ground, you see.

That is because Part 25 does not permit considering nosewheel steering or differential braking in establishing Vmcg. You're going to really confuse yourself when you get into Part 25...especially where we're talking light aircraft certificated under CAR 3 or Part 23. You appear somewhat confused between Vmc and Vmcg, as well as the various certification regulations. No one came up with a reason because there isn't one...it's not used. The stabilizing influence of the nosewheel must be considered negligible, and therefore irrelevant, in establishing Vmcg.

You may well end up in the weeds, but perhaps you've forgotten the most basic requirement of flying the airplane: fly the airplane. Your best outcome occurs when you're still in control. Whether you must still land is really quite irrelevant. Whether you do it under control is very relevant. Again, I'm sure you can tell the difference.

You may never be able to climb away on one engine, depending on the airplane and your available performance. That's something you need to have planned for and calculated before you ever elect to undertake the flight. Know before you go.

That flight will be your refusal speed, sometimes denoted as such, sometimes referred to as decision speed, V1, or in some cases, simply rotation speed. In any event, per the topic of this thread, it needs to be above Vmca, which is really the whole point.

You need to bear in mind that Vmcg is a technical number, as is Vmc. These are certification values. In a light normally aspirated piston twin, Vmc decreases with an increase in density altitude, and decreases in many cases with gear down, with the addition of flaps (though not necessarily), with a forward CG, etc. A published Vmc number does not necessarily represent the number at which directional control is no longer possible. The number may be less, and in some cases, it may also be more. It's a reference number. The same may be said of Vmcg.

Vmcg, for example, is one number; a certification number. The speed at which directional control may no longer be maintained does change; it can be increased at a rate roughly on a ratio of one to one with a crosswind, increasing one knot for each knot of crosswind on the side of the failed engine, and decreases at roughly the same amount for a crosswind from the other side. Other factors may also affect the minimum controllable speed, most notably among them the center of gravity.

You ask why a difference should exist between Vmcg and Vmca, is that it? You want to know why there's a difference between stall speeds clean and dirty? Why some airplanes are monoplanes, some biplanes, some triplanes? Why there's a difference between fast and slow? Or was that just a rhetorical question?

Vmcg occurs typically at a lesser speed than Vmc, but not always; the two may be coincident. Flight speeds are typically greater than ground speeds, as you can guess. The range does not exist between the two because it has a purpose; it does not. It exists because it exists. However, even though one has obtained Vmcg does not mean one is ready to fly, and accordingly one must be above Vmc prior to taking the airplane into the air.

Perhaps you meant something else.

VMCA v VMCG
 

Bookworm, I've been following this thread since leaving these two people to their fun, cos I find the name-calling, patronising assumptions and so on to be a bit dull. I mean, I already went to high school, you know? But I thought their might some pearls of wisdom to be salvaged, or wheat amongst the chaff. (Choose your metaphor :) And there are.

To your specific question re VMCA vs VMCG: "If the aerodynamic forces after an engine failure at that particular speed will roll the aircraft after its wheels have left the ground, why do you think that you will be spared if the wheels are still on the runway? "...well, I wonder if there may be a pretty simple explanation.

It seems to me that you'd much less likely to roll if you're still on the ground, with a high speed engine failure that occurs before rotation, primarily because the "wheels on the runway" act as a stabilising factor against the development of a roll, or to be precise, the wheel that is under the failed engine, and therefore holding up that wing to some degree. Sure, you'll yaw, although nosewheel steering & differential braking may control that to some degree as you retard the working engine...but when on the ground, you have the the main gear to at least partially oppose a rolling motion, no? When practicing high speed engine failures, yes, with a very experienced instructor, I recall a startlingly fast yaw, until the good engine was retarded - but no hint of a roll. And even if a roll did occur and overpower the stability of having wheels on the ground, if you're still on the ground you have a wingtip to hit the ground first, which means that it could be ugly - but probably not as ugly as ending up completely inverted when airborne, where you'll presumably have a serious ROD, even from 20 feet or so, to compound the problem. So the most likely worst case, I would guess, would be departing from the runway - but right side up, and rapidly regaining yaw control as the power from the working engine winds down. Provided you cut power immediately, of course.

Once you're in the air, you've got no wheel on the ground under the failed engine to act as a stabilizing factor, and oppose the rolling motion, so a roll, it seems to me, would be far more likely to occur. And once the roll gets going, it could indeed, perhaps, be difficult to stop given the minimal effectiveness of controls at that speed.

Could it be that simple? The fact that the standard T/O technique is to holding a twin on the ground until VMC or faster would imply so, dontcha reckon?

It certainly might help, depending on how much lift you're getting before rotation. With all the weight on the wheels and no lift, there will be no asymmetric lift and therefore no rolling moment. Once all the weight is off the wheels, the lift is as it is during flight and the aircraft will simply roll into the dead engine. The wheel won't stop the roll, nor will the wingtip. If you're achieving partial lift before rotation, the effect will be somewhere between.

There are many "standard techniques" in aviation that rely on false assumptions or make simplifications that are suitable in one case but not in another.

The aircraft I fly develops considerable lift in its recommended take-off configuration well below Vmca. At Vmca, if I hold it on, I'm holding it on the nosewheel, with no weight on the mains. An engine failure at that stage would be more catastrophic on the ground than in the air (where I could use some bank to assist control). The AFM simply says "keep it on or close to the ground until take-off safety speed".

If an aircraft can be kept on the runway producing little or no lift, and then rotated into a flying attitude, I can see an advantage in staying on the runway until Vmca. Perhaps that's the case for the 340. But I'm not convinced by the general case.

Why not simply use the standard procedures provided by the manufacturer, including the rotation speed provided in the performance charts? How difficult is that?

I think the VG equiped C340 is one of the safest piston twins when it comes to a takeoff engine failure emergency. That is because you can rotate at the 100 knot blueline VYSE speed. If the the oleos are properly inflated the airplane will sit level and therefore not want to fly untill it is positively rotated (this only applies with zero flap). Therefore if you select gear up immediately after rotation (as soon as you have positive rate of climb, of course) you will only have to feather the failed engine and the airplane will be at or above blue line and configured to climb away (i.e. flaps will allready be up and the gear will be retracting/retracted). Our SOP is to keep our right hand on the throttles untill selecting gear up and then move our hand to the prop levers. therefore if an engine failure happens with hands still on the throttles we would automatically retard both throttles and reject the takeoff. If the engine failure occures with our hand on the prop levers we would identify he failed engine (dead foot, dead engine) feather it and concentrate on keeping the airplane straight and set an initial 5 deg nose up attitude then adjust to maintain VYSE. We felt this procedure allowed us to come closest to a large aircraft SOP and therefore their levels of safety.

lostpianoplayer, after a digression into controllability, may I return to what I was going to say before SNS3Guppy and I locked horns (though how a fish and a worm lock horns is beyond me ;))?

The problem, in the context of operating off short fields that require lift off at low speed is this. In the ideal world, engine failures are infrequent and sudden. You recognise the failure, chop the throttles, go through the hedge at the end and accept that the insurance company owns the aircraft.

Real life is less straightforward. You accelerate beyond the speed and runway point at which a safe rejection is possible, but still below Vmca, and the engine coughs -- I could equally propose an oil pressure gauge in the red, or a strange noise from one engine. You now have a choice. You can leave the throttles where they are, continue to try to fly it, and risk a sub-Vmc roll. Or you can close the throttles, go through the hedge and accept the hull loss for sure. It was probably just a little cough, right? How lucky do you feel?

Coughing engines, sticky oil pressure gauages and unfamiliar noises are, fortunately or unfortunately, a lot more common than catastrophic and sudden engine failure. So unless you feel lucky on a regular basis, the price of operating from a short field is a much higher probability of a precautionary abort and consequential hull loss.

Buy a C210. :ok:

Or better still a Roberston STOL C206

340A takeoff procedure
 

Here is how I takeoff in my 340A, in brief form and I welcome any comments or suggestions;

• All pre-takeoff checklists performed.
• This includes accelerate stop distance, which is approximately 3,000 ft by the book; however I prefer a 4,000 ft minimum runway length.
• Obtain clearances as required.
• Lineup on runway, brakes on and increase power evenly to 30 inches MP for three seconds (recommended by Ram Aircraft) and then apply full power while releasing brakes.
• Check for engines gauges in the Green.
• Call our VMC speed, 74 kts.
• Call out Rotation Speed, 91 kts and Rotate, one may also rotate at Rotation minus five knots, but I prefer the higher speed. This is due to wanting to avoid as much as possible any Vmc issues.
• My right hand is on the throttles at max power.
• Depending on weight, CG and DA, actual rotation occurs in low 90’s
• Takeoff occurs and climbout to Vyse, 100 kts. This takes about three seconds from Rotation.
• If anything coughs, pukes, thumps or rattles during this phase of takeoff, I will immediately retard the throttles and land straight ahead.
• Now is decision time. By selecting gear up with my right hand, I am committing to continue the takeoff. I keep my right hand on the gear lever until I see three green lights and I do not put my right hand back on the throttles.
• Accelerate to Vy, 108kts and climbout straight ahead or as directed by ATC to 1000 ft AGL minimum at full power.
• During the initial climbout to 1.000 ft AGL I gradually nose over at the top of the climb profile to approximately 140 kts and reduce power to 32 in MP, 2500 RPM and 1500 EGT, a quick engine scan, and proceed with departure as planned.

I believe this is the best method to pilot a 340A on takeoff. Advantages are;

• You have adequate runway for a rejected takeoff.
• You accelerate through the Vmc speed before Rotation so that Vmc risk is minimized.
• You immediately accelerate to Vyse and then select “Gear Up” as THE decision making moment to commit to the climbout, regardless of engine failure, and treat an engine failure as an in flight emergency.
• At decision speed you are at Vyse 100 kts, and then accelerate to Vyse plus 8 kts. In case of engine failure and the ensuing long moments to identify, verify and feather, a small loss in speed will result in the target speed of Vyse.
• I rarely fly at MGTOW and find the SE climb performance to be 500 fpm or better at GTOW minus 400 lbs.