Twotter engine failure

[xsbank]

It seems to me that there is no prohibition about lifting off below VMC, except airmanship, perhaps, but there is a limitation about using 30 flap for takeoff.

An engine fail at takeoff in a BE18 means close the throttles and land straight ahead. If you damage it, bad luck, no limitations broken (all things being equal). Same thing in a TO with flap 30, land straight ahead; if you do damage and investigation proves that you intentionally had 30 flap down, you might be toast.

I see a difference there.

[goldeneagle]

It seems to me that there is no prohibition about lifting off below VMC, except airmanship, perhaps, but there is a limitation about using 30 flap for takeoff.

There is no prohibition regarding a pilot forcing the liftoff prior to VMC. For normal and utility category, there is a prohibition in the certification process regarding a configuration where liftoff prior to VMC cannot be prevented. The reason is simple and strait forward, certification for light planes which dont require type endorsement requires that failure conditions can be handled by an 'average pilot using normal technique'. Normal technique as taught in a basic MEL course is 'power up, flaps correct (normally up in light training twins), gear up, blue line, feather and secure the dead engine, climb to a safe altitude at blue line'. ofc the 'gear up' is irrelavent for the twotter. In an aircraft lifting off prior to VMC, an abnormal technique is required, power back, land strait ahead. This will introduce limitations into the AFM which prohibit 'normal use' of configurations where the early liftoff is not preventable.

I took a quick peek at the TC website, and indeed, there does appear to be a DHC-6 specific op spec (098) regarding STOL operations. I couldn't find much / any detail on it, other than it requires 3 hours of specific training for the pilot, and insinuates the initial training should be done in the simulator, but recurrent in an airplane is acceptable. Other posts here insinuate that with that op spec, flap 30 on wheels for takeoff is indeed acceptable. Can anybody enlighten us with a little more detail, ie what does the op spec specifically allow? Are these allowances in conflict with the AFM prohibitions ?


This doesn't seem a lot different different than the op specs for reduced visibility takeoffs. As a licensed commercial pilot, I can blast off into 1/2 mile visibility IFR quite legally in any airplane I am qualified to fly. If I head off to flightsafety, take the sim course for the airplane, and that sim course includes reduced visibility takeoffs (1/4 mile), and engine failures at prescribed points during those takeoffs, I can apply for and recieve an op spec to do 1/4 mile takeoffs in the real world, on the airplane for which I am trained to do it. This is a recognition by the certification gods that indeed, proper training does allow a pilot to operate an airplane safely in conditions beyond the capability of the 'average pilot with normal technique', who is the target of various certification bullet points. In this case, proper training is indeed type specific, and, the op spec will only cover those types in which the training was completed, will not carry over onto other types.

But this whole topic has me very curious about more things. Was the flaps 20 limitation in the original twin otter AFM as delivered in the 65, or did it come about in an amendment in later years ? Is the verbiage 'not recommended' or 'prohibited' ? Does op spec 098 require AFM changes, or, is it just laid out in training manuals? What does the AFM say with regards to flap settings when doing a go-around from a full flap approach?

This is one of the fascinating things about the whole aviation industry, and it's pre-occupation with paperwork. The armchair experts (lawyers qualify as armchair experts) seem convinced that a twin otter is going to fall out the sky in a flaming fireball if flaps are selected to 30 at takeoff. BUT, if all the right paperwork is put in place, then suddenly that same airplane, in the same configuration, is safe. It's a fascinating concept.

[Chuck Ellsworth]

BUT, if all the right paperwork is put in place, then suddenly that same airplane, in the same configuration, is safe. It's a fascinating concept.

Op spec.......

.......my, my, my how comforting.

Our op spec was determined by how proficient you were with the airplane.

You want something fascinating Golden one all you need do is remember the approval for your op spec could come from that TC crew that couldn't figure out how to do an instrument approach in that King Air at Edmonton a few years back.......comforting huh?

[CD]

I took a quick peek at the TC website, and indeed, there does appear to be a DHC-6 specific op spec (098) regarding STOL operations.

Here it is, in case anyone is curious:

Operations Specification 098 - Maximum Performance STOL (MPS) Take-Off - DHC-6 Twin Otter Aeroplane

[shimmydampner]

Can anybody enlighten us with a little more detail, ie what does the op spec specifically allow? Are these allowances in conflict with the AFM prohibitions ?

Is it a "prohibited" or perhaps just "not approved."

This is one of the fascinating things about the whole aviation industry, and it's pre-occupation with paperwork. The armchair experts (lawyers qualify as armchair experts) seem convinced that a twin otter is going to fall out the sky in a flaming fireball if flaps are selected to 30 at takeoff. BUT, if all the right paperwork is put in place, then suddenly that same airplane, in the same configuration, is safe. It's a fascinating concept.

This is exactly the point I'm trying to make.

By pure coincidence, today I came across a very relevant article entitled "Arctic Sovereignty" in the July/August 2007 issue of Canadian Aviator. It discusses the work the military DHC-6s are doing in the arctic. Here's an interesting tidbit:

Bob Fowler, de Havilland Canada's chief engineering pilot, once boasted to have landed the Twin Otter across the Downsview taxiway, a distance of about 200 feet (60 metres). "And that's not a flat slow approach. That was for demonstration." Asked what his shortest take-off distance was, Fowler answered, "In STOL mode? With a bigger flap angle? About the same."

The Twin Otter can actually take-off on one engine. "We don't put a procedure on it," Fowler admitted, "But I've done it." Fowler has told people on the phone how to do it. "And they've phoned me back to say it went just like I said it would."

Fowler stressed the single-engine take-off is completely unapproved and he wouldn't want anybody to try it without talking to him first. "But, say you lose an engine and you've got to land on some little island, as alot of these planes do. It's sometimes easier to fly back to the mainland than to get a replacement part out by boat."

Food for thought from a guy who should know.

[Doc]

Now there's an intelligent quote. Lets all just fire one up, and see what she'll do? I would consider anyone contemplating a trick like that, a total moron. But hey, that's just me. You'd best go get a couple of hours in the old Twin Otter, and get back to us on that one?

More like...Food for thought, by someone who should know BETTER"

I'm sure it's physically possible to launch in the odd twin, single engine.....but WHY would you??

[shimmydampner]

I don't know, but I would assume that the chief engineering pilot for the aircraft would be more than familiar with exactly what the aircraft is and is not capable of safely doing. I would put forth that if he feels comfortable enough to do something with his own ass in the seat and under extenuating circumstances tell others how to do the same in a safe manner, it's probably not as close to certain death as some would have us believe.
Why would anyone? I don't know, but I guess it has something to do with a person's own idea of acceptable level of risk. Test pilots make a living out of pushing the envelope of safety, but why? Some non-pilots refuse to fly period because they think it too risky, but why? Some pilots choose to strap large ungainly items to the outsides of their aircraft when after everything we learn about the theory of flight and the physics of aerodynamics would indicate that it's probably not conducive to the ideal handling characteristics of the aircraft? Some pilots think that any operation less than the legal by-the-book envelope is equivalent to operation outside of the safety envelope and as such will result in certain fiery doom. I would hazard a guess that most test pilots would tell you that that is certainly not the case. Apparently, too few pilots recognize that operating within the legal envelope will ensure nothing more than a legal flight, not necessarily a safe one.
Like I said from the get go, and goldeneagle reiterated:

The armchair experts (lawyers qualify as armchair experts) seem convinced that a twin otter is going to fall out the sky in a flaming fireball if flaps are selected to 30 at takeoff. BUT, if all the right paperwork is put in place, then suddenly that same airplane, in the same configuration, is safe. It's a fascinating concept.

Another excellent point. A given aircraft cannot be considered legal (and as such, unsafe, in some people's minds) when using 30 flaps one day, but the next day if the proper sheet of paper arrives from TC, that exact same, unaltered aircraft is now completely legal and safe to use 30 flaps. That's one powerful piece of paper if you ask me.
It's like the upgross kit for an Otter. Doesn't help the aircraft fly better with more weight, doesn't add any power to the engine, just a couple of strut cuffs if I'm not mistaken. But with those cuffs and the proper piece of paper, you can now legally fly overloaded.

[Doc]

I've done quite a few 30 flap take offs. That was before the "paper' was a requirement. Sure seems to be a lot safer than a single engine take off, with any flap setting?

Legal does not equal safe.
Safe does not equal legal.

Illegal CAN be perfectly safe, while legal CAN kill you.

[shimmydampner]

Thanks Doc, that's all I'm trying to say.

[rightseatwonder]

As far as I have been shown over the years the wording is take off PROHIBITED with flaps more than 20 for float equipped DHC-6.

I think I see the points being made... there is no doubt here by any responsible or reasonable pilot or person that if you take off exceeding the prohibited limit of flaps 20 you are hanging your ass out to dry if anything happens. everybody gets it.

That being said I think the other side of the discussion (because there should be no debate about illegally operating any aircraft) is that the DHC-6 can take off just fine with flaps 30 as demonstrated by countless pilots on countless flights over 40 some odd years.

Can it do it? yes. Will it save your ass, your airplane in some situations? yes yes. Is it legal? no.

the big debate here it seems,

IS IT SAFE? that seems to be a relative term in regards to experience.

I think that the safety of the business of flying aircraft (in this country) is sometimes loosely connected to the business of governing the safety of flying aircraft. In some cases these 2 things just don't seem the same.

[Doc]

Any comments I've made about the Twin Otter have been for wheel ops. My float time on them is limited to a few right seat trips.

[xsbank]

Gentlemen, I am not arguing that 30 degrees of flap on floats for takeoff is not safe or not possible. Not the issue.

If you anticipate and knowingly do something that is breaking a limitation to complete the trip, you will be hosed if something breaks.

Besides, if its ok to break limitations when the mood strikes, why not just push the thrust levers to the wall when you're in a hurry, ignore the barber pole, load her up to the nuts, take less fuel than legal because one of the hunters brought too much booze, take that last trip and land after grounding time... whatever?

Its the get 'er done at any cost attitude that was laudable when I was a kid but now has become the feeding ground for lawyers and insurance companies, and now the courts, that has me all exercised. I LOVE bush flying and the skills you develop after using your wits for years to "get 'er done," a lot like skiing the double-diamond runs but there you only risk your own ass; nowadays you are flying so close to the edge of litigation, permanent license loss, bankruptcy, perhaps jail that you really have to be disciplined about what you are prepared to do or attempt, for the mere challenge or fun of it.

The cowboy is dead. Long live the cowboy.

[rightseatwonder]

xsbank.

please re-read the last few posts.

then stop this thread unless you have some new ideas or position that we AREN'T agreeing with.

cheers,
RSW

[xsbank]

Oh poop. And I was having such fun.

Oh well...

[snoopy]

CLguy,
I've been away from the forums for some time of late, so have only just noticed your post.
Having visited our operation in person, I am disappointed in your comments, and refute your accusations:

"I to am a little reluctant to wade into this contraversy since 30 flap take-offs are pretty much an everyday event for us as was flying a Beech 18 off the water at about 24 knots below VMC back in the days. Carholme I agree with you on the loads for sure but your operation as all who operate Beech 18's are still operating outside of the POH. I suspect your pilot does not allow the aircraft to crash through the waves to the 84 kt. VMC ( I'm sure that is the number but it has been a long time) before lifting it out of the water. I suspect she uses the 60 kt lift off speed as every other Beech 18 pilot I have ever came across does.

For the record, VMC for the D18S landplane is listed as 95 mph or 82kts. The approved supplement for the D18S floatplane states for a short run take-off to use 10 degrees of flaps and "Lift the aircraft off the water as soon as it is ready to fly". There is no stipulation for minimum or maximum speed to depart the water.

Also, for the record, and from your own experience, I am sure you are well aware that there are alternate ways of good airmanship to prevent the aircraft from being smashed to bits in rough water. Often this includes extended taxi for calm water, and more often than not, I can be found taxiing for extended periods to save the airfame.

I hope you will apologize for your statements, and rest assured, if you have any doubts about how we operate our aircraft and whether or not we operate within the bounds of the POH then I challenge you to visit us and we will prove it.

Sincerely,
Kirsten Brazier
DaxAir Inc.

[stallie]

I have been following this thread with interest.

Whilst it has digressed a little towards the VMC side of things, can I ask what the procedure is for ski operations with the twotter? Are you airborne below VMC?

The ski twins I fly are in the air below VMC (an approved procedure).

Cheers

[the_professor]

CLguy,
I've been away from the forums for some time of late, so have only just noticed your post.
Having visited our operation in person, I am disappointed in your comments, and refute your accusations:

"I to am a little reluctant to wade into this contraversy since 30 flap take-offs are pretty much an everyday event for us as was flying a Beech 18 off the water at about 24 knots below VMC back in the days. Carholme I agree with you on the loads for sure but your operation as all who operate Beech 18's are still operating outside of the POH. I suspect your pilot does not allow the aircraft to crash through the waves to the 84 kt. VMC ( I'm sure that is the number but it has been a long time) before lifting it out of the water. I suspect she uses the 60 kt lift off speed as every other Beech 18 pilot I have ever came across does.

For the record, VMC for the D18S landplane is listed as 95 mph or 82kts. The approved supplement for the D18S floatplane states for a short run take-off to use 10 degrees of flaps and "Lift the aircraft off the water as soon as it is ready to fly". There is no stipulation for minimum or maximum speed to depart the water.

Also, for the record, and from your own experience, I am sure you are well aware that there are alternate ways of good airmanship to prevent the aircraft from being smashed to bits in rough water. Often this includes extended taxi for calm water, and more often than not, I can be found taxiing for extended periods to save the airfame.

I hope you will apologize for your statements, and rest assured, if you have any doubts about how we operate our aircraft and whether or not we operate within the bounds of the POH then I challenge you to visit us and we will prove it.

Sincerely,
Kirsten Brazier
DaxAir Inc.

CLGuy, you just got OWNED.

[justplanecrazy]

CLGuy, you just got OWNED.

Wow that was mature, why I expected something more from you, is what really surprises me!!! Especially when you're lecturing a bunch of professor's on a subject that you know absolutely nothing about!!!

[the_professor]

CLGuy, you just got OWNED.

Wow that was mature, why I expected something more from you, is what really surprises me!!! Especially when you're lecturing a bunch of professor's on a subject that you know absolutely nothing about!!!

Mature, like CLGuy chastizing someone for what is an approved procedure? (or at least not a prohibited procedure)

Seems to me that it's him that doesn't know what he's talking about.

[CLguy]

Kirsten, you obviously missed the point I was trying to make and I certainly wasn't alluding to the fact that you run an unsafe operation. I was just trying to point out that lots of aircraft over the years operate, and very safely outside of what the books say. The Beech 18 is a perfect example when you compare the lift off speed with the VMC. I am willing to bet in a court room a lawyer could make this sound very unsafe and very dangerous which could be the difference between a pilot being vindicated or hung!!

Professor, not sure where you get the impression I was chastizing anyone. If you reread my post I was just stating how it is done which is the same procedure I used for years and every other pilot that I know who has time on a Beech 18. You certainly would never be taught to lift a multi-engine aircraft off 22kts below VMC on any initial Multi-Engine course. In fact I would like to hear the response from most instructor if they were asked about doing it.

[Cat Driver]

I am trying to understand what is being discussed here.....about a twin engine airplane on floats and the best method of handling rough water.

So lets look at what is going on.......

The airplane is pounding the living chit out of itself because of wave action and it has enough airspeed to fly.

So we can pull it into the air and accelerate to a safe airspeed in ground effect.....if an engine fails we close the thhrottles and land straight ahead.

Or we can continue to pound the living chit out of the floats and the airframe waiting for some magic number to appear on the airspeed indicator?

Lets see now......lift off and accelerate to a safe climb airspeed?

OR.....keep pounding the chit out of the airplane on rough water?

Please be kind to me because I'm only asking questions.....if I really wanted to know what an expert advises I could ask CID.

[Hedley]

Golly, being airborne, straight & level in ground effect
below Vmc sure sounds dangerous to me! Imagine
what would happen if an engine burped - why, you'd
have to land! Gosh, that sounds like a truly awesome
use of stick & rudder skill, worthy of Bob Hoover himself!



I personally like to half-roll inverted at 80 mph immediately
after takeoff, and accelerate inverted in ground effect. At
the end of the runway, it's time for an outside 1/2 cuban-8:
push through the vertical, back to the upright vertical 45
downline, then a 1/2 roll inverted again, then a push
back to inverted at the surface.

Gosh, flying below Vmc sure sounds tricky to me! How
do you multi-engine guys manage it?

[Cat Driver]

Gosh, flying below Vmc sure sounds tricky to me! How
do you multi-engine guys manage it?

From reading this forum Headly my guess is some of them don't quite understand the issue at all let alone handle it right.

[justplanecrazy]

Cat, that's the way the industry has gone. We're no longer supposed to use good logic but rather know the rules and abide by them and nothing else. Just look at some of the guys posting on here. I don't have near enough hours to discuss what is safe and isn't safe with you or CLguy or anyone that has spent 1,000's of hours flying complex aircraft in extreme environments. I'll still add my two bits and take in any info that's provided by experts like Golden Eagle before making my own decisions, but others on here feel that all they need to know is the rule and then they can tell you whether or not you're a menace to society.

I had a friend that flew heli at the north pole. He'd drop scientists off on ice flows and pick them up after they had drifted miles over the week. I remember hearing his storys about flying in fog so thick that he'd have to get the guys on the flow to tell him when he flew overhead, so he could go back and pick them up. He was flying with no compass, no GPS, in a heli in virtual IMC, in order to pick up a crew that had run out of food and needed out now. He just did what he had to do. No-one questioned the safety or the sanity of the operation, hell he got shot down 4 times in Nam before working this, so it was nothing to him. So how did we go from this being an acceptable operation to crapping on people operating an aircraft in a manner that apparently is quite safe other then the book not saying it's ok?

[Cat Driver]

So how did we go from this being an acceptable operation to crapping on people operating an aircraft in a manner that apparently is quite safe other then the book not saying it's ok?

That is easy to answer......lawyers and rule makers looking for any and all things that " MAY " be a reason to sue someone over or fine them for.

The bottom line on this subject of rough water airplane handling is get the thing in the air under control at the lowest speed that can be managed.....

However it would seem that there is a movement in aviation to dumb everyone down to the lowest common denominator and then set that in concrete so you have an army of robots operating airplanes on the water pounding the living fu.k out of the machine because some assho.e has them paranoid to the point they will wreck a perfectly good airplane because they were programmed to follow numbers.....

How about the poor bastard that gets in the airplane and has a strut fitting fail on take off because some numbers monkey fractured it pounding over the water when they could have been flying over the water?