Hi,

Does anyone know if there are any legal requirements to achieve any particular single-engine climb performance in a light twin - preferably on-going requirements, but otherwise requirements for a new-from-the-factory aircraft?

The aircraft I'm specifically interested in is a Beech Duchess, so I imagine it would have had to have passed FAA requirements when it was new. It's now on the G register, so JAA requirements would be useful too. What I'm specifically looking for is something which I can either show to an engineer and say "this aircraft does not meet this requirement, therefore it needs fixing", or alternatively show to a pilot and say "this aircraft meets this requirement, so it's ok to fly".

Thanks!

FFF
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Aha - I might have just found the answer. I took a rare visit into the Flight Testing forum, and found this thread (http://www.pprune.org/forums/showthread.php?t=296256), with this link (http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY%5CRGFAR.NSF/0/2459CA427595FBF685256687006BC958?OpenDocument). If I read it right, the answer to my question is that, because Vs0 on my Duchess is less than 61kt, there is no climb requirement. Have I got that right?

FFF
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Hello Flying for Fun,

All the information you're looking for can be found in FAR23.66 "Takeoff climb" and the other nearby paragraphs. If it is an earlier aircraft, CAR 3 standards might apply, but they are quite similar. FAR23 should be easily found on various websites. It is certainly on the FAA website, but not easy to find.

Do not expect to just go out and perform such a test. It requires a lot of precision to get an accurate result, and would be UN-NECESSARILY UNSAFE to test close to the ground. If the plane otherwise flys in trim, seems to handle properly, and has proper control travel available, the only other consideration for poor performance would be engine(s) not developing adequate power. Climb testing of any kind is probably the least effective way to diagnose engine power problems. Most of that kind of investigation is done on the ground by maintenance staff.

Cheers, Pilot DAR

Can't help you on the reqs really, but I have some other input that you may want to consider.
One of Sweden's largest schools, training hundreds of pilots per year, uses the Duchess for ME training. They have specific operating procedures that keeps them far far far far away from stall conditions at any point of flight in that particular aircraft type. The Duchess is considered vicious close to stall and especially on one engine. In general single engine climb performance will be poor.

An aircraft fit to stay clear of...

Having raised myself reading stories of Beauforts, Beaufighters, Mosquitos etc going into uncontrollable yaw/roll modes if they lost an engine on takeoff, could anyone who actually drives light twins tell me what it's like these days if you lose one engine just when you've left the ground? Is it ever practised or is it better avoided?

Just out of curiosity you understand.

If you know what Performance Category the a/c is in, you'd be able to find any climb requirements in JAR-OPS (or the FAA etc. equivalent) in the corresponding section.

V1R :ok:

Sedbergh,

I fly PA34 Seneca aircraft and we often practice engine failures after takeoff (usually at about 200' AGL) and they are, by necessity, perfectly managable. Speed control is important though - if you drop below Vmca (minimum control speed with one engine inoperative), you run the risk of not being able to maintain directional control, even using both rudder and ailerons. At altitude you could pitch down to speed up again and thereby get control back but you'd have limited options near the ground :bored:

V1R :ok:

Ta Vee

hoped it must be something like that! I've always wondered slightly about small twins. I used to get flown out of Nairobi in a Partenavia P68 - grand until the pilot told me one day what height it would level out at, fully loaded on one.

A lot lower than Nairobi!:{

Yeah, wouldn't like to get into certain corners in a Seneca either.

In a hot climate, even moderately loaded and at moderate altitudes, when you bin an engine in the cruise you're sometimes forced to drift down as you can't maintain altitude, even with the Seneca's twin turbos :(

Of course, it was always in the name of practice and we weren't MSA-limited!

V1R

If you know what Performance Category the a/c is in, you'd be able to find any climb requirements in JAR-OPS (or the FAA etc. equivalent) in the corresponding section.

From memory (which is fallible), and its been a few years since I flew the Duchess, I think its perf E, but don't put any money on it :}

Brooklands

Does it have to perform at all? Most Duchesses I have flow have crap SE performance, just like most training aeroplanes (Seminole for ex).

I'd use the SE ceiling, as ceiling is defined as rate of climb of less than 100 fpm. If the SE ceiling is low, (4000' ish) as it is for many light twins then I'd assume it wouldn't climb. Some are better than others, for example the Seneca II will got o 13,000' on one engine by virtue of the turbos.

Of course if you drop below Vmc and you don't have height to loose the ONLY thing you can do is reduce power or else you are dead. Part of the FAA ME rating is to perform a Vmc demo (at height ;)) where you fail and engine, then go full power on the other and pitch up to let the speed decay to below Vmc. The thing that surprised me was the speed at which you loose it when it goes.

Part of the FAA ME rating is to perform a Vmc demo (at height ;)) where you fail and engine, then go full power on the other and pitch up to let the speed decay to below Vmc. The thing that surprised me was the speed at which you loose it when it goes.

Unless it is a turbocharged aircraft Vmc is a bit academic "at height" as the live one won't be developing anything like 100% power.

Did the instructor/examiner wedge something (their foot for example) under a rudder pedal to simulate loss of rudder authority at "Vmc", or did you actually allow speed to go well below Vmc and therefore close to stall speed - which engine out is fairly exciting.

Does anyone know if there are any legal requirements to achieve any particular single-engine climb performance in a light twin - preferably on-going requirements,
...
What I'm specifically looking for is something which I can either show to an engineer and say "this aircraft does not meet this requirement, therefore it needs fixing", or alternatively show to a pilot and say "this aircraft meets this requirement, so it's ok to fly".


Surely the answer is "the Approved Flight Manual". I don't know what the tolerances are for SE climb, but if it doesn't do what the AFM says it does, it needs fixing.

Just out of curiosity you understand.

You will do them on your initial MEP.

You will probably do them on your renewal.

Depending on the twin the performance varies significantly as does handling for all the usual reasons concerned with where the engine is mounted and which one it is, or whether it has rather nice counter rotating props.

I dont think things have really change with "modern" twins - not that there are very many. The DA42 at MTOW has little performance reserve and because rather like most modern aircraft the airframe is "slippery" to extract the most from low powered engines managing the aircraft on one engine is critical. At MTOW in my opinion you need to be right on the ball should the worst happen at the most critical time and it could easily catch out a rustle or low time pilot.

Unless it is a turbocharged aircraft Vmc is a bit academic "at height" as the live one won't be developing anything like 100% power.

Did the instructor/examiner wedge something (their foot for example) under a rudder pedal to simulate loss of rudder authority at "Vmc", or did you actually allow speed to go well below Vmc and therefore close to stall speed - which engine out is fairly exciting.
Yep true. Isn't it called Coffin Corner where Vmc and stall coincide?

It was a Seneca II and so was TC'd (actually develops more HP at altitude than sea level). The examiner didn't wedge his feet under the rudder pedal then, though I believe now they are advised to do so nowadays. I think I would if I were an examiner ;) I chatted to one FI who lost 5000' in a Vmc demo gone wrong....:eek:

Regarding the DA42 - we failed one engine at 5000' in California last year. The weather was reasonably warm, we had lots of fuel (long range tanks) and 3 blokes with overnight baggage onboard. The thing perfomed amazingly and we had no problem climbing at all....(being TC'd helps of course).

At MTOW in my opinion you need to be right on the ball should the worst happen at the most critical time and it could easily catch out a rustle or low time pilot.

WTF is that supposed to mean? :hmm:

You are only legally required to have single engine climb performance when operating commercially and in a situation where you can not see and avoid obstacles.

Since you are probably providing training for the CPL then the requirments of JAR-Ops for perfromance class B are appropriate for understanding the situation.

In terms of "is this aircraft performing correctly" then the reference is the flight manual which will schedule the gross performance that the aircraft should manage.

Apply your factors to get net performace and confirm that the aircraft is meeting those requirements with ease.

I would not use the certification standards to confirm performace of an established aircraft as the aircraft may have be designed to exceed those minimum performance standards and while grossly underperforming may still meet the minimum requirement.

The flight manual is your legal guide. The Manufacturer will also help.

The friendly pilots at the CAA flight test department will also help you with a better and more specific answer.

Regards,

DFC

Yep true. Isn't it called Coffin Corner where Vmc and stall coincide?

Not traditionally, no. The Coffin Corner is something else entirely.

Nathan is correct. Coffin corner is a situation when you cannot go slower nor faster without stalling or exceeding speed limits. Typically a problem with swept wing jets that climb high enough that stall and Mmo coincide.

With regard to Vmc and stall, it isn't a corner because you only need to increase speed to get out of it.

At MTOW in my opinion you need to be right on the ball should the worst happen at the most critical time and it could easily catch out a rustle or low time pilot.

WTF is that supposed to mean?


I'm pretty sure it's supposed to be a compliment, saying that you are a high time pilot and not normally easily caught out. ie. you're the contast to the low time pilot.

People find insults anywhere they can :rolleyes: Are you sure you're not an ex g/f of mine? :p

WTF is that supposed to mean? :hmm:

Could it just be a spoonerism of sorts?

How about:

"At MTOW in my opinion you need to be right on the ball should the worst happen at the most critical time and it could easily catch out a rusty or low time pilot."

:8

Thanks for the references and thoughts, everyone. Pilot DAR - you are, of course, correct about investigation being done on the ground by maintenance staff - but they swear nothing is wrong, and I'm not convinced, which is why I'm asking the question.

The POH certainly contains performance graphs, but I don't think (and I'll have to double-check this) they are any different between de-iced and non de-iced aircraft. The maintenance organisation tell me that they would expect a de-iced aircraft to not perform as well as the manual says because of the de-icing strips on the leading edges. That's why I was looking for something else... but it seems that this something else is not there, or if it is it's impractical for me to use anyway.

Sedbergh,could anyone who actually drives light twins tell me what it's like these days if you lose one engine just when you've left the ground? Is it ever practised or is it better avoided?My company doesn't allow simulating engine failures below 200'. At 200', it's no problem at all as long as you do everything correctly. If you don't do it correctly, all bets are off. (Only very recently, a student of mine went for the wrong rudder pedal when I failed an engine at 500'. It didn't take very long at all before the student lost control completely, and asked me to take over. I did - but only because a crash was imminent if I hadn't - closed both throttles, levelled the wings, back under control again. But of course that's not an option closer to the ground.)

As for being below 200', this ought to be taught in a sim, and those of my students who go on to do the IR with me all experience it. I don't usually pre-warn them I'm going to do it, although they all know the company standard pre-takeoff brief which says that if a problem occurs on the ground, or in the air with the gear still down and runway still ahead, close both throttles and land back on the runway. The majority of students, despite having just briefed themselves on what to do, try to take the failed engine into the air without enough speed to maintain control. Every single one of them crashes, and every single one of them never makes that mistake again.

FFF
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PS - Rustle, I don't know if it's just me, but I took Fuji's comment to be a typo, intended to be "it could easily catch out a rusty or low time pilot"? Edit, because Bravo beat me to it!

Well I'm pleased for you that you three see the "error" in that light (compliment or typo), but having had > 24 hours and multiple visits* to the site to fix it it remains unaltered.

* Everyone is visible when they're here and I have visited a few times today when FA has been around; anyone posting to a thread would normally return to it to see any follow ups.

Sorry, the question remains: WTF you on about FA?

FFF,
You need to look at assumed engine failure height. IE, for an MEP, the engine is assumed not to fail below (300' I think, although it's been a while). As the engine is assumed not to fail below this height, if it does you are guaranteed jack sh*t. This will be in your ops manual among other places. After this height, you must be able to construct a +tive climb with obstacle clearance to 1500'. This info is in the POH, and is up to the pilot to determine for any given conditions.

Good job punters don't know this when they get in the likes of a chieftain!

Gulp:uhoh: - it all sounds like a recommendation for big singles! It worked for Mr Lindbergh:)
Ok, scenario - Boeing 777 full of Sedbergh and his overweight hand baggage, mainwheels just left the deck, one engine sheds the turbine blades - does el Capitano have shut the other down & land straight ahead???? M25 here we come?

I know, wrong thread & accusations of scaremongering but just out of interest!

Ok, scenario - Boeing 777 full of Sedbergh and his overweight hand baggage, mainwheels just left the deck, one engine sheds the turbine blades - does el Capitano have shut the other down & land straight ahead???? M25 here we come?


If he's already in the air then he's already past V1. So he continues, sheds a bit of fuel and then lands (either where he came from or, if needed, diverts elsewhere.)

(Or, at least, that's my very basic understanding of the situation. Although I'm sure that Kit will be along in a bit to patronise me then set me straight...:rolleyes:)

Brav

But just because you're past V1 it sounds from other posts if you're not necessarily past Vmc?? - at least in some a/c.

I'm sure Mr Boeing has it all worked out:ok:

V1 is the decision point. If a power unit goes before this point, you stop. If a power unit goes after this point, you continue.

Unless of course, the B777 was sat at the end of, say, a 20,000ft runway. Then the captain might decide that he's got enough room to stop in. (But then you don't get many of those!) ;)


Here's what Wiki has got to say about V1:

V1 critical engine failure recognition speed. V1 is the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff with only the remaining engines. Any problems after V1 are treated as inflight emergencies. In the case of a balanced field takeoff (http://en.wikipedia.org/wiki/Balanced_field_takeoff), V1 is the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the aircraft within the accelerate-stop distance and the minimum speed at which the takeoff can be continued and achieve the required height above the takeoff surface within the takeoff distance. In this context, V1 is the takeoff decision speed.

But just because you're past V1 it sounds from other posts if you're not necessarily past Vmc?? - at least in some a/c.

I'm sure Mr Boeing has it all worked out

Mr Boeing makes exclusively Performance Class A aeroplanes. Mr Beech does not.

Did some IR training in a BE76 in Canada, and single engine in the missed with 2 onboard and near full fuel provided fairly good climb performance at sea level, even in above ISA conditions. Also did some IR training in the Seneca 1 and that thing was a pig. We only practiced engine failure in the overshoot simulated at altitude, and until you got the a/c cleaned up it was pretty much at zero climb even with the good engine firewalled. That assumed you got on the pedals quick and rolled five degrees into the live engine.

JAR OPS states perf B for MEP light twins. So, requirement to clear obstacles by 50 feet (I think) to 1500' after take off and a 1000'/5nm positive gradient en route clearance requirement as well as being able to hold altitude at or above MSA.

Used to fly Piper Chieftains for Air Taxi. That thing had a VG kit on it that upped our MTOW to 7348Ibs from 7000Ibs, however I would put money on the fact that if we'd lost an engine below 400' or safe obstacle clearance height, we might have just held altitude up to about 7000 on a good day. The SE service ceiling was supposed to be 13800...my point being that performance figures in the POH are based on a shiny new test aircraft!

But just because you're past V1 it sounds from other posts if you're not necessarily past Vmc?? - at least in some a/c.

Not for airplanes certified by the FAA. V1 must be equal or greater than Vr, and Vr must be greater than Vmc.

Gulp - it all sounds like a recommendation for big singles! It worked for Mr Lindbergh
Ok, scenario - Boeing 777 full of Sedbergh and his overweight hand baggage, mainwheels just left the deck, one engine sheds the turbine blades - does el Capitano have shut the other down & land straight ahead???? M25 here we come?

The thread is about light twins, so lets not get confused and get a load of replies about V1 etc. This does not apply to MEP type aircraft (perf B).
JAR OPS states perf B for MEP light twins. So, requirement to clear obstacles by 50 feet (I think) to 1500' after take off and a 1000'/5nm positive gradient en route clearance requirement as well as being able to hold altitude at or above MSA.

Nearly correct, except that it is after assumed engine failure height, ie 300'. My previous comment stands, that below this you are guaranteed jack.

All the comments about my twin performed ok on this or that occasion are not of any value in answering the question. FFF wants the air law side of things. He flies light twins, so knows how they perform. I have to say though that I am surprised by the amount of people who do appear to fly them without knowing the facts!

Ref a post near the beginning....

IF the POH states a "SE Ceiling of 3000' "then you must be able to climb at >100 fpm at MAUW to SE ceiling. If you can't then the plane is not performing (after taking into account density alt of course).

as well as being able to hold altitude at or above MSA.
What happens when MSA is 10,000'? No way will a BE76 at MAUW climb.....

All the comments about my twin performed ok on this or that occasion are not of any value in answering the question. FFF wants the air law side of thingsVery true, AB! I do find the thread creep interesting, though, I have to admit - so long as it doesn't detract from the answers to the original question.I have to say though that I am surprised by the amount of people who do appear to fly them without knowing the facts!I think a lot of the posts on this thread are from people who don't fly twins, which is why there is a lot of confusion, and a lot of discussion of V1 (which does not apply to light twins, as others have said). In fact, there is so much wrong information on this thread I'm tempted to ask the mods to delete it in case anyone starts quoting things from it! Normally I'd try to correct the errors, but there are too many here to know where to start!

Anyway, thanks for all the input. As it happens, I had a chance to fly the aircraft in question with one engine feathered just the other day, and I have made a note of all the relevant numbers to compare to the POH when I get a chance. I will also repeat the exercise with another aircraft in the fleet and compare both the performance and the POH for the two aircraft. Hopefully that will give me enough data to decide whether I need to push the issue any further with my maintenance organisation.

FFF
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