A interested sideline, having nothing to do with the original topic, came on up this thread regarding single-engine ferry of a twin-engine airliner:
A310 'Quirks' (by airportugal310 Oct 10 2010 in Tech Ops)

Rather than continue to hijack the A310 discussion, I figured we should move the topic over here...so, to be continued on the topic of single-engine ferry on twin-engine airliners...

1) Has it ever happened? I can find anecdotal evidence of at least two incidents (an A310 flown by the father of a forum member and an A330 into Copenhagen) but nothing firm. I've found some evidence that American Airliners had the procedure in their manuals, though never used it, and a claim that the Twin Otter actually has it in the AFM although I don't have that document so I'm not sure. A relevant quote from the prior thread:
"You have misunderstood AA's procedure."

This may be true but, absent any explanation of where the understanding lies, this isn't helpful. More elaboration would be greatly appreciated.

2) Is it physically possible? Absolutely...the engine-out requirements for twins mean that, given sufficient runway, they're all capable of doing a single-engine takeoff, climb, cruise, landing (and go-around if need be).

3) Is it certifiable? This is where the conversation gets interesting. I believe it is, many other believe it is not. Some relevant quotes:

"No entity could or would assume that liability under any circumstances."
This one is flat-out false because OEM's assume this liability all the time while doing single-engine testing. There is no technical reason why an airline couldn't do the same.

"No OEM would provide such a statement, under any circumstances,"
This is also flat-out false, since the OEM themselves have done all the required maneuvers before therefore, by definition, they don't have a technical objection.

"There is no regulatory process in existence with any aviation authority that would approve a single engine ferry flight of a two engine jet transport...As someone involved in flight test I am very surprised you are not aware of this Tds !"

It's actually because I am involved in flight test that I know exactly what the regulatory procedure is. Flight testing requires doing things, on a daily basis, that are *way* outside the AFM operational envelope of the airplane, yet we do it all the time and it's completely certified (just certified under different regulations than revenue service). It's important to note that any hypothetical ferry flight of this type is *not* operating under Part 121 regulations so the fact that you can't do this in revenue service is entirely moot.

To break it down, a hypothetical single-engine ferry would require all of the following on one engine:
1) Taxi from where you are to the runway
2) Accelerate to V1
3) Rotate and takeoff
4) Climb/cruise/descent/land (go-around if necessary) at the destination.

An important fact is that 3, and 4 above are all completely certified on all commercial twins to do on one engine *with revenue passengers onboard*, and 1 is covered by many airline OpsSpec's even though it's often not explicitly called out in the AFM.

The only part not covered by existing procedures, AFM, certification, etc is 2 (accelerate to V1 on one engine). However, all the data to do so does exist, including how much thrust you can apply on one engine without losing directional control below Vmcg, what Vmcg is for the current configuration, how much runway you'd need to get up to Vmcg, and how much you'd need to get from Vmcg to V1 with one engine at full thrust and one inop. The procedure is relatively simple and has been practiced (successfully) in simulators more than once by more than one transport pilot.

I'm entirely comfortable with the idea that nobody has actually done this because I can't imagine a situation where single-engine ferry is the preferable option to sending a new crew and engine to the airplane, but that's completely different than the claim made by some that "It would not be permitted, under any circumstances.".

All data exists to provide a statement of no technical objection, the risks are no higher than existing engine-failure at V1 (which is acceptable in revenue service therefore obviously acceptable on a ferry), and the regulatory process to issue such a permit exists (and the process is used on a regular basis to do things that are considerably more dangerous).

Discussion from all fronts welcomed...

Tom.

Quoting tdscanuck (Thread starter): I'm entirely comfortable with the idea that nobody has actually done this because I can't imagine a situation where single-engine ferry is the preferable option to sending a new crew and engine to the airplane, but that's completely different than the claim made by some that "It would not be permitted, under any circumstances.".

Given that it's *almost* always going to be possible to ferry a replacement engine and tech crew to the aircraft, I think the only plausible scenarios would be those where that *isn't* possible.

Perhaps an aircraft in imminent danger of destruction - perhaps a hurricane bearing down on the airfield in a timeframe not permitting an engine change. I could see having a runway with nothing off the end of it that you could hit (for example, a runway pointing over the water) to be a plus for approving this sort of thing.

And it's not like the darndest things *haven't* be approved. Consider the Taca 737 taking off from the levee outside New Orleans a couple of years ago.

Nor is approval necessarily a requirement. People have taken grossly overloaded airliners out of war zones, which is unlikely to ever be approved by anyone.

Quoting rwessel (Reply 1): Perhaps an aircraft in imminent danger of destruction - perhaps a hurricane bearing down on the airfield in a timeframe not permitting an engine change. I could see having a runway with nothing off the end of it that you could hit (for example, a runway pointing over the water) to be a plus for approving this sort of thing.

The imminent destruction thing is possible. However in that case I believe the airline would take the insurance payoff. If for some reason insurance wouldn't cover it, I don't know that an airline would ask its pilots to risk the procedure.

Another scenario is imminent loss of life. Very hypothetically:
- Tsunami on low-lying island with no hills.
- Volcanic eruption.
- Attack during war, insurgency or terrorist action.
- Alien attack.
- "2012" event.

Ok I jest a bit, but certainly there are times when a single engine take-off would be the preferable option. Those situations are not very common though.

Quoting Starlionblue (Reply 2): Those situations are not very common though.

No argument there...I'm not saying this has been done (although anecdotal evidence does exist), just that it could be done if someone really wanted to. As soon as you're not risking the lives of paying passengers or those on the ground, the regulatory landscape gets a lot more open. The FAA is generally willing to let trained crews do almost anything they like provided the only lives they're risking are their own.

Tom.

It has been alleged that a Trans-Texas Airways (the airline you now know as "Continental," at least for a little longer...) Convair once departed Amarillo single-engine, headed to Dallas.

Quoting Starlionblue (Reply 2): The imminent destruction thing is possible. However in that case I believe the airline would take the insurance payoff. If for some reason insurance wouldn't cover it, I don't know that an airline would ask its pilots to risk the procedure. Another scenario is imminent loss of life. Very hypothetically: - Tsunami on low-lying island with no hills. - Volcanic eruption. - Attack during war, insurgency or terrorist action. - Alien attack. - "2012" event. Ok I jest a bit, but certainly there are times when a single engine take-off would be the preferable option. Those situations are not very common though.

There is a bit of precedent from the military side - the USAF has emergency takeoff procedures and checklists designed to get aircraft off the ground as quickly as possible, presumably cutting things to the bare minimum. Of course the Air Force has to consider the destruction of a base as a "normal" planning event, so it makes sense to have procedures developed and in place to try and save extremely valuable and hard to replace assets, even at some risk of accident.

In any event, attempting to get aircraft out of an airport threatened with a hurricane is fairly SOP for everyone.

Quoting Starlionblue (Reply 2): Another scenario is imminent loss of life. Very hypothetically: - Tsunami on low-lying island with no hills. - Volcanic eruption. - Attack during war, insurgency or terrorist action. - Alien attack. - "2012" event.

I think in a situation like this you get the hell out of there first and worry about regulations and certifications later.

Quoting tdscanuck (Thread starter): "No entity could or would assume that liability under any circumstances." This one is flat-out false because OEM's assume this liability all the time while doing single-engine testing. There is no technical reason why an airline couldn't do the same.

Quoting tdscanuck (Thread starter): "No OEM would provide such a statement, under any circumstances," This is also flat-out false, since the OEM themselves have done all the required maneuvers before therefore, by definition, they don't have a technical objection.

I think you just answered your own question. The OEM do all the REQUIRED maneuvers and they don't really get into the areas they don't need to. Such as single engine takeoff. True the numbers might exist or can be calculated but the real question is "is it done?". That's where you refer to your first statement.

The single engine testing you are referring to is engine cuts at V1 and single engine approaches and single engine go arounds. However, there is no single engine takeoff testing done at all.

So from a liability point of view the OEM would never issue a NTO to the regulatory body to approve single engine takeoff in a 121 carrier. In addition, if it were an international ferry, which I have done several times, the regulatory bodies for all the airspace you have to fly through have to be notified and they can disallow an overflight.

I am still waiting for someone to provide an example, not a friend of a friend said, but a real example that can be verified.

Granted that a wartime situation is different but I know for a fact that an A-26 did a takeoff from Libya single engine, flew across part of the Sahara desert, and landed at a maintenance base, all on one engine. I know the guy who did it.

According to the FAA, a single engine ferry on a twin is not legal. That's not to say it is not legal in other jurisdictions.

A certain former a.net former forum member (who happens to be a dispatcher for a very major airline here in the US) pointed this out to me in the forums many moons ago   

That said, I knew a crazy old coot who was a P-38 driver in World War II ( a rare enlisted man who got his wings in the Army Air Corps during the war, just like Chuck Yeager). He has since flown West and is exercising his wings in different realms, but he claimed to have taken off in a P-38 with one mill shut down, and flown around the patch, to settle a bet during the war (happened at a backwater base in the Pacific Theatre where not much was going on...and hopefully while the CO was looking the other way!)

It should be technically possible though, in an aircraft certified to Part 25 (think of all the single-engined climb requirements that a modern transport category aircraft has to conform to).

Quoting Vmcavmcg (Reply 7): The single engine testing you are referring to is engine cuts at V1 and single engine approaches and single engine go arounds. However, there is no single engine takeoff testing done at all.

That's why I specifically said "all the maneuvers"...through various testing, you end up doing all the pieces (single engine taxi, single engine acceleration, single engine from V1, single engine climb/cruise/descent/go-around/landing). There's no one piece where you do them all together to do a complete single-engine flight, but that's because there's no test reason to do so.

Quoting Vmcavmcg (Reply 7): So from a liability point of view the OEM would never issue a NTO to the regulatory body to approve single engine takeoff in a 121 carrier.

An NTO carries no liability implication (unless there is in fact a technical issue)...I've written plenty of them, they say 42 ways from Sunday how this doesn't constitute approval, the regulator has to approve, it's only valid for reasons X, Y, Z, etc. It is purely, only, and solely a technical opinion, not an operational or legal one and is very explicitly *not* an endorsement (they often contain verbiage that the OEM actually does *not* recommend it).

Quoting Vmcavmcg (Reply 7): In addition, if it were an international ferry, which I have done several times, the regulatory bodies for all the airspace you have to fly through have to be notified and they can disallow an overflight.

Absolutely true.

Quoting KELPkid (Reply 9): According to the FAA, a single engine ferry on a twin is not legal.

What's the law (FAR)? The FAA has the authority to deviate from any FAR I'm aware of, and the FAR's are the law for aviation (at least in the US).

Tom.

Quoting tdscanuck (Thread starter): 3) Is it certifiable?

Actually, I just realized that not only is it certifiable, it's *certified*. I'm not sure why I didn't clue in to this before. Any commercial twin, before it obtains type certification, is under an experimental certification in the R&D category. Under such a certification you could do a single-engine takeoff without any additional paperwork provided you comply with the special conditions of the experimental certificate (which wouldn't prohibit single-engine operation in any phase).

That means, from a regulatory point of view, you'd "just" need to pull the type certificate and re-hang the experimental R&D certificate and you'd be covered. This actually happens all the time (the re-ticketing, not the single-engine ferry), so not only does the appropriate regulatory process exist, it's been done many times before.

Tom.

Quoting tdscanuck (Reply 10): What's the law (FAR)? The FAA has the authority to deviate from any FAR I'm aware of, and the FAR's are the law for aviation (at least in the US). Tom.

And I quote 14 CFR Part 91:

Quote: § 91.611 Authorization for ferry flight with one engine inoperative. (a) General. The holder of an air carrier operating certificate or an operating certificate issued under part 125 may conduct a ferry flight of a four-engine airplane or a turbine-engine-powered airplane equipped with three engines, with one engine inoperative, to a base for the purpose of repairing that engine subject to the following: (1) The airplane model has been test flown and found satisfactory for safe flight in accordance with paragraph (b) or (c) of this section, as appropriate. However, each operator who before November 19, 1966, has shown that a model of airplane with an engine inoperative is satisfactory for safe flight by a test flight conducted in accordance with performance data contained in the applicable Airplane Flight Manual under paragraph (a)(2) of this section need not repeat the test flight for that model. (2) The approved Airplane Flight Manual contains the following performance data and the flight is conducted in accordance with that data:

Note that subpart A doesn't say a word about twins  

Quoting tdscanuck (Thread starter): 2) Accelerate to V1

If you're going on just one engine, there is no V1... Just Vr.

Well, actually, there's technically the speed past which there isn't enough runway to stop, which half fulfills the definition of V1, I guess...  

The takeoff is made assuming the one good engine is not going to fail past that speed.
I really doubt whether the manufacturers even bother doing perf calculations for a single engine takeoff, and if they were asked to, they'd probably want to know a damn good reason for pulling such a stunt, a pretty exhaustive list of which has already been posted above.

But if you throw the legal aspect out of the window, it can probably be done. You'd have to use a power setting low enough so that your Vmc is always lower than your actual speed during the roll, so probably a gradual spool up until T/O power Vmcg where you can firewall it.
That would also probably mean that you need a very light aircraft, a very long runway and a couple of unmarried pilots with no children.

Quoting francoflier (Reply 13): If you're going on just one engine, there is no V1... Just Vr.

I was involved with some two engine ferries on the Tristar, and actually flew on the jump seat on two occasions.

there was no V1. Until we got to V2, there was no single engine climbout facility and with a second engine failure the aircraft would have gone down.

We learnt the hard way about minimum control speed. The first GF ferry was out of JED to BAH. The max temp for the performance was 34degC, so the ferry was planned for 0400 when the temp finally went below this. During the take off roll the pilot advanced the wing engine power too quickly and the aircraft went off the runway. They taxied back to the ramp, and checked it all out, but by now the sun was up and the temp too high.
The following night all went well.

Because of the second engine failure problem, we carried out a very full boroscope of the two working engines, we also fitted two new nose wheels! The aircraft was completely empty, no catering trollies, no cargo bins, water and toilet tanks empty, just flight deck manned. On the runway, the good wing engine was run up to 100pc for one minute, and then back to idle, then the Nbr 2 engine run up to 100pc for a minute, and then brake release. As the speed increased, the good wing engine was increased until it was at 100pc at 100kts. At Vr you rotated, and held your breath as you waited for V2.
Ferry range was about an hour for a -22B and about 2 hours for a -524. I flew MCT-BAH on a -22B aircraft, and KHI-BAH on a -524.

I wonder how much runway you would need to get up to Vr on a twin, feeding the power in very slowly. You may run out of nose wheel tyre rubber before you get there!

Quoting Vmcavmcg (Reply 7): The single engine testing you are referring to is engine cuts at V1 and single engine approaches and single engine go arounds. However, there is no single engine takeoff testing done at all.

Depending on the runway length, that may be a severely limiting factor. Using T/O thrust on both engines till V1 and then cutting out one engine is one thing, using limited thrust on just one and bringing it up to max rated thrust gradually as airspeed builds up to Vmcg is another. I imagine it could be done but one would need a very long runway. And in that case, a long runway may well be able to handle a cargo aircraft carrying a spare engine.

It would be very interesting to know in what circumstances such a T/O may actually been have carried out.

Faro

A twin-engined biz jet tried this single-engined takeoff technique at PDX a few years back...didn't work out so well.

Report reads like a Darwin Award candidate? Pretty amusing nonetheless.

http://www.ntsb.gov/ntsb/brief2.asp?...211X09774&ntsbno=SEA98FA047&akey=1

Quoting tristarsteve (Reply 14): Until we got to V2, there was no single engine climbout facility and with a second engine failure the aircraft would have gone down.

There would not have been any anyway, at anywhere near V2, with only one engine operating.
L1011, standard body aircraft...

Even if very light weight (mass, for our Euroland friends) needs to be at the following speeds/configuration, to enable a climb, with one engine only, serviceable...
Minimum 180 knots IAS, retract flaps to 4.
At 210 knots, retract flaps to zero, and continue climb at 210 knots, minimum.

Follow the procedure to the letter, and the airplane will indeed fly, IF that second engine fails.

Quoting tristarsteve (Reply 14): Ferry range was about an hour for a -22B and about 2 hours for a -524.

This depends entirely on the departure airfield temperature, and the temperature aloft, on the intended route.
For example, I have personally two-engine ferried a -22B aircraft, from Baku to Taba...4:20 enroute.
Max altitude flown, FL240.

Quoting KELPkid (Reply 12): And I quote 14 CFR Part 91:...Note that subpart A doesn't say a word about twins

Exactly...it doesn't say anything about twins. That FAR authorizes one-engine out ferry for tri- and quad-jets. It does *not* prohibit single-engine ferry of twins, so something else is needed to support this statement:

Quoting KELPkid (Reply 9): According to the FAA, a single engine ferry on a twin is not legal.

If there is no FAR prohibiting something, then it's legal (as far as aircraft go).

For example, if we extend your 14 CFR Part 91 reasoning to other areas, according to the FAA eating a tuna sandwich in flight is not legal.

Tom.

Quoting tristarsteve (Reply 14): During the take off roll the pilot advanced the wing engine power too quickly and the aircraft went off the runway.

No formal training in engine inop ferry procedures, I expect.
IE: one does not send a child to do a man's job.
A familiar GF trait.

Quoting Starlionblue (Reply 2): - "2012" event.

All the old farts hitting 65 and finally ending this 5 year stagnation because of their poor planning? Or the Mayan thing? Either way the world is going to end.  

Quoting tdscanuck (Reply 18): For example, if we extend your 14 CFR Part 91 reasoning to other areas, according to the FAA eating a tuna sandwich in flight is not legal.

Well, didn't Airplane! teach us all that the flight crew shouldn't eat the fish?  

We actually tried this in the sim once. We did make if off the runway, but we used all of about an 11,000 ft runway doing so. The hardest part was advancing the power on the good engine in synch with the increasing control authority.

I think the biggest obstacle would be that there are very few airports in the world where one could do this, and still meet the obstacle clearance planes. You use up so much runway just getting the power set, and arrive at Vr so far down the runway with such poor climb performance, that you you have a hard time clearing much more than your typical dog house.

As far as the FAR's are concerned, wouldn't one just need to apply for a ferry permit?

It's against the FARs to fly an unairworthy plane, but with a ferry permit you can fly one. Happens all the time. Plus, from what I've heard, as long as your flight doesn't pose a risk to others, the FAA will hand out a ferry permit for just about anything.

So presumably a twin with only one operational engine is unairworthy, but with a ferry permit and the right meteorological conditions, I don't see why it wouldn't fly.

Just a brief return to reality here !






You can speculate all you like about what might be possible, trying out single engine take offs in a simulator etc..





But it doesn't really matter. No twin engine Jet transport is certified for or would be approved, by the OEM or relevant Aviation Authority even under a ferry permit for a single engine ferry, period.




Tds, you claim that this 'has been done' but base this statement purely on hearsay or the word of another.




You have no first hand evidence yourself of such a flight, as VMCA has mentioned.




There is a good reason for this, the dangers involved far outweigh any possible benefit of developing or carrying out such a procedure.

Quoting Max Q (Reply 24): Just a brief return to reality here !

Ok, we now return you to your regularly scheduled treadmill and snowglobe discussions.

Quoting chrisjw (Reply 23): As far as the FAR's are concerned, wouldn't one just need to apply for a ferry permit?

Yes. The difficulty is in all the substantiation you'd require for the ferry permit but, from a regualtory point-of-view, the ferry permit would provide all the coverage you need once granted.

Quoting chrisjw (Reply 23): Plus, from what I've heard, as long as your flight doesn't pose a risk to others, the FAA will hand out a ferry permit for just about anything.

Correct.

Quoting Max Q (Reply 24): No twin engine Jet transport is certified for or would be approved, by the OEM or relevant Aviation Authority even under a ferry permit for a single engine ferry, period.

You have yet to explain why. If my hearsay isn't good enough, then yours isn't either. The airplane is technically capable of doing it, a ferry flight permit allows it under the regulations, and it doesn't violate any FAR's.

Quoting Max Q (Reply 24): Tds, you claim that this 'has been done' but base this statement purely on hearsay or the word of another.

I didn't claim it had been done. I claimed there is evidence of it having been done, which I can't confirm.

Quoting Max Q (Reply 24): You have no first hand evidence yourself of such a flight, as VMCA has mentioned.

I said it too, in addition to VMCA. The question isn't whether it has been done, but whether it can be done.

Quoting Max Q (Reply 24): There is a good reason for this, the dangers involved far outweigh any possible benefit of developing or carrying out such a procedure.

What danger? The *only* portion of the entire maneuver that isn't already certified *with revenue passengers onboard* is the acceleration from taxi to Vr. And that technique, although unusual, isn't more difficult or dangerous than several other maneuvers that are certified (again, with revenue passengers on board).

Tom.

Quoting francoflier (Reply 13): Well, actually, there's technically the speed past which there isn't enough runway to stop, which half fulfills the definition of V1, I guess...

Yes, but if you have an engine failure past your "single-engine V1" you are stopping. You may not stop on the runway, but you ain't taking off without divine intervention.

Quoting tdscanuck (Reply 26): Yes. The difficulty is in all the substantiation you'd require for the ferry permit but, from a regualtory point-of-view, the ferry permit would provide all the coverage you need once granted.

There is no amount of substantiation that would allow for a single engine ferry flight of a twin engine jet transport.



Such a flight would present severe risk to the crew and those on the ground beneath the flight path.

Quoting tdscanuck (Reply 26): You have yet to explain why. If my hearsay isn't good enough, then yours isn't either. The airplane is technically capable of doing it, a ferry flight permit allows it under the regulations, and it doesn't violate any FAR's.

As much as it suprises me that I would have to explain this to a flight test expert I will attempt to.



Firstly no performance charts exist to attempt a single engine take off in a twin engine jet transport, ferry or not you need to know if you can get off the ground.




You don't actually know the Aircraft is capable of doing this do you ? See above, no data is available to support such a reckless attempt. How would it not violate FAR'S if this maneuver has never been certified, even for a ferry flight ?



Three and four engine jet transport manufacturers did certify one engine inop ferry flights as there was a clear benefit in doing so. No such benefit exists on a twin !



There is no redundancy. It is NOT the same as planning for an engine failure at V1 in which two healthy engines provide normal acceleration to a known point on the runway at which you can either stop or fly away clearing all known obstacles.



If you attempt a single engine take off and are unable to stop on the runway with an engine failure there is only one outcome, a crash, how would this potential outcome be acceptable to the crew, the OEM or the relevant aviation authority ?



You say a ferry flight would permit this under the regulations, why not show us evidence of this ?

Quoting tdscanuck (Reply 26): I didn't claim it had been done. I claimed there is evidence of it having been done, which I can't confirm.

An individual can claim many things have been done on an anonymous forum. That is not evidence of anything and if you cannot confirm it, why, with your flight test background would you choose to believe it ?

Quoting tdscanuck (Reply 26): What danger? The *only* portion of the entire maneuver that isn't already certified *with revenue passengers onboard* is the acceleration from taxi to Vr. And that technique, although unusual, isn't more difficult or dangerous than several other maneuvers that are certified (again, with revenue passengers on board).

Once again, I am more than a little surprised you fail to see the dangers in an attempted single engine take off in a twin engine jet transport.



You imply the maneuver is 'already certified' it is not. How do you come up with the conclusion it is 'no more difficult or dangerous' than other certified maneuvers ? !





To summarise:




The Aircraft is not certified for this and was never designed with this capability in mind even on a ferry flight , unlike many three and four engine jet transports.





The risk is MUCH greater , assuming you can find a runway long enough to do such a reckless thing, if you do lift off and lose your sole powerplant a crash is a certainty.



This would not be acceptable / certifiable / approvable to anyone involved.

Quoting Max Q (Reply 28): The Aircraft is not certified for this and was never designed with this capability in mind even on a ferry flight , unlike many three and four engine jet transports.

That's why special permit would be needed. For which there is no prohibiting law, as tds proved. Including laws of physics.

Quoting Max Q (Reply 28): The risk is MUCH greater , assuming you can find a runway long enough to do such a reckless thing, if you do lift off and lose your sole powerplant a crash is a certainty.

You do realize that for a twin losing engine after V1, loss of second engine makes the crash a certainity, don't you? So how is it possible to accept such a reckless thing as single-engine takeoff of twin after V1?

Quoting 3MilesToWRO (Reply 29): You do realize that for a twin losing engine after V1, loss of second engine makes the crash a certainity, don't you? So how is it possible to accept such a reckless thing as single-engine takeoff of twin after V1?

You are not correct, in a twin engine Jet transport a loss of one engine after V1 is planned for on every take off. In this case the Aircraft is able to rotate, clear all obstacles in the departure path on the remaining engine and return for a safe landing.



These criteria can be met even if the Aircraft is departing using a reduced power setting (no power increase on the remaining engine is necessary)



If the weather at the departure Airport is bad, in our case (B757 / 767) we are authorised to fly on one engine up to 440 miles to an alternate airport.




These options do not exist when you have lost all power in all engines !



Of course, in a twin engine Aircraft, losing both engines when airborne after V1 will make crashing a near certainty, as it would losing all engines in a 3,4 or 8 engine aircraft.




These are some of the many reasons why a single engine ferry on a twin engine jet transport has not been and is not permitted.

[Edited 2010-10-17 01:01:28]

First question: does it work performance-wise?
A healthy twin has a thrust-weight ratio of .28-.3 (at MTOW).
A quad has a thrust-weight ratio of .23-.25 (at MTOW).

The OEW/MTOW ratio of a modern aircraft is about .55 (long range) to .6 (short range).

We assume a medium fuel load, no payload, arriving at 75% of MTOW.
Assuming a thrust-weight of .3 (@MTOW) we get:

0.5 * THR / 0.75 * MTOW = 0.5*(0.3*MTOW) / .75 * MTOW = .15/.75 = 0.2
That is about the thrust-weight ratio of a B47 and probably a bit low for a conventional take-off.
A bit less fuel might probably boost the thrust-weight to .23.

So, I think performance-wise it is possible, yet it's a stretch.

Amendment to first question: What do we assume the other engine is doing? In flight test a One Engine Out usually means a cut to Flight IDLE. A really dead engine is a different thing. It doesn't only deliver zero thrust, it delivers substantial drag! First by its aerodynamic drag, second by the required trim drag. Especially at low speeds this can be substantial.

Second: controllability. Keeping an aircraft fully aligned to the runway from standstill to VR with one engine at TOGA and the other delivering either no thrust or drag (frozen engine). The required rudder deflections (we are talking about pedal to the medal for the whole take-off run) will add drag. So, even if the thrust-weight ratio looks OK, the thrust-drag ratio (which is very essential in second segment climb) will look ugly.

My conclusion: it might work, but it is very narrow and I wouldn't try it, even as a test pilot. Maybe with an A318 with 30k CFM56.

[Edited 2010-10-17 02:58:07]

Quoting SchorschNG (Reply 31): So, I think performance-wise it is possible, yet it's a stretch.

A discussion with the manufacturer and authorities will never reach this stage.

Insurance company says:
this is outside the documented operations there we need an statement from the manufacturer.

Manufacturer says:
we don't take liability for a single engine T/O.

Insurance company says:
we don't issue a insurance.

Authorities say:
You are not legal to fly without appropriate insurance.

And that's it really, making the rest irrelevant.

Performance wise... Vmcg... Hmmm, gonna be a daaaaaaamn looong single engine take off on a twin then...
*since airliners aren't approved for CATO...*
BUT then... how about... RATO single engine ferry on a twin?   
Seriously, anyone want to put the sole remaining engine on take off thrust, then MCT... for anything more than 60mins, is kind of insane... (if from cruise, it's OK, let the ETOPS do the talking for >60mins)...

Now if it's

Quoting Aviopic (Reply 32): And that's it really, making the rest irrelevant.

If I would limit my thinking to the scope of aircraft insurance, I wouldn't get far.
My fist question is always: is it physically feasible?
Second question is the legal one.

If the answer to the first is "NO" we do not have to discuss the second (I think a zero engine take-off is perfectly certifiable). If the answer to the first is "YES, but ..." the second one might get interesting.

I think the reason the FARs don't cover this is because it isn't contemplated that someone would want to do it. I'm sure tds is correct that approval is theoretically possible though. If I was a pilot, I would not want to put my life to such risk to save the airline a few dollars.

If an L10-11 could only fly 1-2 hours on two engines, I'm guessing that the endurance would be even more severely challenged for this flight.

Quoting thegeek (Reply 35): If an L10-11 could only fly 1-2 hours on two engines, I'm guessing that the endurance would be even more severely challenged for this flight.

I don't know where you got the information that the L-1011 (not L10-11?) could fly only 1-2 two hours on two engines? I personally know Hawaiian Airlines two engine ferried at least one L-1011 from HNL to LAX. That flight take slightly more than two hours?

Quoting DocLightning (Reply 27): Yes, but if you have an engine failure past your "single-engine V1" you are stopping. You may not stop on the runway, but you ain't taking off without divine intervention.

Well, that's what I meant, really. There is no decision speed because the engine will make that decision for you...

Quoting pilotpip (Reply 20): All the old farts hitting 65 and finally ending this 5 year stagnation because of their poor planning? Or the Mayan thing? Either way the world is going to end.

 

Quoting 474218 (Reply 36): I don't know where you got the information that the L-1011 (not L10-11?) could fly only 1-2 two hours

See below. Or did that only apply from a very hot and/or high airport? I'm confused now.

Quoting tristarsteve (Reply 14): Ferry range was about an hour for a -22B and about 2 hours for a -524. I flew MCT-BAH on a -22B aircraft, and KHI-BAH on a -524.

Tristarsteve is severely misinformed, the L1011 can fly well over four hours with one engine inoperative...I know, because, I have done so several times, personally, in the LHS.

Quoting 411A (Reply 39): Tristarsteve is severely misinformed,

Well, was only a technician on the Tristar, merely observing what I saw, and the Capt told me.
But it was a bit upsetting to be sitting behind the Captain as we were about to take off from MCT (in the summer around 40degC) and finding out that there was no single engine climb performance for the first few minutes. I hadn't been told that before they took the steps away.
I had just boroscoped the two good engines. In 1980 there were no good engines, There were bits missing and eroded, but within RR limits. I had to decide whether a dent in an HPC blade was OK, and decided it was, and then wished I hadn't.

Yes I am sure the L1011 can fly 4 hours on a two engine ferry. Just needs a cooler temp and a longer runway to carry all that extra fuel.

I did most of my Tristar work in BAH where the summer temps are 35 to 40 degC.

Quoting thegeek (Reply 38): Or did that only apply from a very hot and/or high airport? I'm confused now.

Tristarsteve has provided his opinion that it is temperature related? As for high airport: There is that famous EA two engine ferry flight from MEX - MIA that lost the second engine right after liftoff?

A very interesting thread, and far removed from our normal world.
First let me say that I've done one one-engine-out takeoff on the Tristar. The technique iwas as tristarsteve described, with some added infgormation ; rudder trim set.. Full rated thrust on number 2 engine, checked and stabilised... brake released and F/O will call out ASI, FE the wing engine N1 as the aim is to match both values : "50 knots...50%...60 knots...60%...etc...
therefore, we should have had full thrust at 100 Kt +
We were committed , IIRC, at 100 Kt.

I do not see another Vmca-avoiding technique on a twin in the idiotically suicidal scenario we are contemplating , which means that as a matter of fact, we have an acceleration to 100 kt at an average 65% N1, and then another at 100% from 100kt to Vr (which makes a few remarks on thrust-to-weight ratios completely wrong). I would be curious to see such a manufacturer's performance chart.
As the main principle of our certifaication is about considering en engine failure at every moment of the flight and as the main message on a twin ECAM is "LAND ASAP" I'd be curious to see how one's legal department would solve this situation.

Quoting tristarsteve (Reply 40): Yes I am sure the L1011 can fly 4 hours on a two engine ferry.

Steve, it was not recommended to have a windmilling engine for too long : lubrification was awful and totally unequal and the damage to the engine wasn't consideried worth going the extra risk of extended flights.

Quoting Pihero (Reply 42): Steve, it was not recommended to have a windmilling engine for too long : lubrification was awful and totally unequal and the damage to the engine wasn't consideried worth going the extra risk of extended flights

yes I know,
One of my flights the fan blades were removed and the engine blanked.
The other one, we actually had the engine running at idle. It had suffered a birdstrike with twisted fanblades. Boroscopes OK, but after we had fitted a new set of fan blades there was fan vibration at high power. So we left the engine at idle and called it a two engine ferry.
Bit of a c-up involved. We had fitted a new fan set straight from RR. The blades were numbered 1 to 33 as usual and we fitted them correctly (so we thought).
the next day, the engine shop supervisor apologised to us. Accompanying the fan set should have been a fitting sheet, produced on the fan test stand at RR, that said fit blade nbr 22 in nbr 1 posn, etc. They had neglected to send it to us!

Quoting 411A (Reply 17): mass, for our Euroland friends

Do they not have gravity over there?  

Quoting tdscanuck (Reply 18): If there is no FAR prohibiting something, then it's legal (as far as aircraft go).

Well, FAR 121.159 (an operational reg, not a certification reg) states in pertinent part, that

Quote: No certificate holder may operate a single-engine airplane under this part.

For US air carriers, we operate under US Operations Specifications, and OpSpecs D084 covers the maintenance ferry. It states

Before operating an aircraft that does not meet applicable airworthiness requirements, the certificate holder shall determine that the aircraft can be safely flown to a station where maintenance or alterations are to be performed. The certificate holder shall have the aircraft inspected or evaluated according to procedures in its manual and have a certificated mechanic or repairman certify in the aircraft record that the aircraft is in a safe condition for the flight as specified in the operator's manual. The certificated mechanic or repairman may certify only for the work for which he or she is employed.

and...

Only flight crewmembers and persons essential to the operations of the aircraft shall be carried aboard during ferry flights where the aircraft flight characteristics may have been appreciably changed or its operation in flight substantially effected.

The operating weight of the flight must be the minimum necessary for the flight with the necessary reserve fuel load.

Lets say that our aircraft for this exercise is a B737W, with 7B26 engines.

In the AFM, there is a table showing unless the weight is over a certain weight (126000), you may not use full rated thrust - you must use a derate. During testing of the B777, Boeing discovered Vloc, a loss of control airspeed that can creep up and be a limitation when you are very light - they had to increase takeoff V-speeds, when very light, to insure that Vloc doesnt become an issue. (Tom, I'd love to see those analyses - I'll give you my BEMS ID and send em my way  

Anyway, the OpSpec says your weight must be at an absolute minimum, and below 126000 (for our notional B737W) you cant use full rated thrust, so to take off at reduced thrust single engine - well that doesnt sound like a good time to me. Plus, FAR 121.159 says no single engine ops.

Nope, not gonna dispatch it. I've done an engine out ferry on a BAe146, and I have read the 3-engine ferry AFM Appendix for the B744 and I feel comfortable doing those - because people much smarter than I have done the engineering and said it can work. But, on a twin, with one motor out, nope - not gonna do it.

[Edited 2010-10-18 12:38:31]

Quoting dispatchguy (Reply 45): But, on a twin, with one motor out, nope - not gonna do it.

I am not eager to try it, but it is an interesting hypothetical. One other factor that I don't think anyone has brought up is the associated loss of redundancy of other systems. Engine driven generators, hydraulics, and bleed systems all spring readily to mind. Obviously if you lose an engine in flight, the remaining systems only have to get you safely to the next suitable runway, but if you look at it in terms of ETOPS, you couldn't dispatch with most of these inop, so I think the feds would be reluctant to issue a ferry permit with all of these potentially compounding problems.

Quoting dispatchguy (Reply 45): Well, FAR 121.159 (an operational reg, not a certification reg) states in pertinent part, that

Quoting dispatchguy (Reply 45): Nope, not gonna dispatch it.

Right, but the flight, if it happened, wouldn't be operating under Part 121 for a thousand other reasons.


Jimbo

Quoting Pihero (Reply 42): I do not see another Vmca-avoiding technique on a twin in the idiotically suicidal scenario we are contemplating

This is, perhaps, the best description I have seen of this idea !

Quoting Lowrider (Reply 46): so I think the feds would be reluctant to issue a ferry permit with all of these potentially compounding problems.

Under D084, it is the airline that issues the ferry permit - not the FAA, and can only issue a ferry permit for an aircraft on its operations specifications. If an aircraft has been involved in an accident or incident, the aircraft may not be moved without the NTSB's blessing, but it is still the airline that is responsible for making any inspections to insure the aircraft is safe for the ferry flight. Furthermore, a special ferry inspection must be completed and signed off in the logbook by a mechanic saying that the aircraft is authorized for a one-time special ferry for the purpose of moving the aircraft to an airport where repairs can be made. The ferry inspection says that the aircraft is safe for the ferry operation, and that the aircraft flying characteristics havent been appreciably changed. If they have been changed, then only the minimum required flight crew only may be aboard. If they havent been changed (for example, ferrying an airplane to a maintenance base when the only offending item is a drop dead MEL that died at an outstation - and not in base) then additional non-revenue personnel may be carried aboard the flight.

If a Mech were to sign off a twin on a ferry flight with an engine out, then that person needs to no longer hold an A&P certificate!

Airline flight crew are not test pilots, and may only operate the aircraft in accordance with the FAA Airplane Flight Manual - if the manufacturer isnt going to set forth a set of procedures on how to do this, then there is no way in hell I am going to allow one of my flight crew to be a test crew. Like I said earlier up thread, there is an appendix to the FAA AFM for an engine-out ferry on the B744, so if we had to engine out ferry a 744, there is set of manufacturer tested and approved procedures on how to do it - and I feel comfortable enough to dispatch it. When my airline operated B727s, we had appendix 28 - which allowed an engine-out ferry for a B727 (at least with JT8D-15 engines).