Jet Engine Out Bank Angle
Thread Starter
Jet Engine Out Bank Angle
Elsewhere on the forum there is a post implying (perhaps to this reader) that an engine out on a 737, 777 etc is flown with the ball centered. Fact, or do you still bank (how many degrees?) towards the live? Reading the drills on the net it talks of pitch angle, among all the rest, but no mention of bank.
Many thanks.
Many thanks.
Moderator
Several considerations -
(a) at much lower than normal speeds (at/near Vmc) one needs to crank in some bank (certification limit is 5 degrees) towards the operating engine(s) to achieve expected handling characteristics. Achieved Vmc is very bank angle dependent. Climb performance is not the name of the game at this sort of speed .. staying right way up is. Indeed, there may well be no climb in this speed region .. the aircraft often will be in a descent.
(b) once the OEI situation is sorted out and the speed is up at/near the optimum climb speed, best climb performance is achieved with 2-3 degrees for most aircraft. This is a fairly demanding flying exercise for other than a short period. Hence one normally trims out the control loads to suit.
(c) some attitude systems don't like small bank angles so the technique is to fly wings level and accept a small loss in climb performance. Alternatively, if terrain clearance is not super critical on the day, the pilot probably will prefer to fly wings level due to the reduced workload. Some aircraft will have spoiler deployment with other than a "level" control column so that is a driving concern, for such Types, towards flying wings level.
(d) at higher speeds, the need for bank is minimal and one normally chooses to fly wings level.
(e) flying straight with any bank angle, you won't have a centred ball .. it will be displaced somewhat towards the low side. Conversely, wings level, the ball should be centred as there will be no force to displace the ball from centre.
Piston, jet, glider, rubber band powered model aircraft ... makes no difference to the ball situation.
Pitch angle will be appropriate to speed, thrust and Type.
(a) at much lower than normal speeds (at/near Vmc) one needs to crank in some bank (certification limit is 5 degrees) towards the operating engine(s) to achieve expected handling characteristics. Achieved Vmc is very bank angle dependent. Climb performance is not the name of the game at this sort of speed .. staying right way up is. Indeed, there may well be no climb in this speed region .. the aircraft often will be in a descent.
(b) once the OEI situation is sorted out and the speed is up at/near the optimum climb speed, best climb performance is achieved with 2-3 degrees for most aircraft. This is a fairly demanding flying exercise for other than a short period. Hence one normally trims out the control loads to suit.
(c) some attitude systems don't like small bank angles so the technique is to fly wings level and accept a small loss in climb performance. Alternatively, if terrain clearance is not super critical on the day, the pilot probably will prefer to fly wings level due to the reduced workload. Some aircraft will have spoiler deployment with other than a "level" control column so that is a driving concern, for such Types, towards flying wings level.
(d) at higher speeds, the need for bank is minimal and one normally chooses to fly wings level.
(e) flying straight with any bank angle, you won't have a centred ball .. it will be displaced somewhat towards the low side. Conversely, wings level, the ball should be centred as there will be no force to displace the ball from centre.
Piston, jet, glider, rubber band powered model aircraft ... makes no difference to the ball situation.
Pitch angle will be appropriate to speed, thrust and Type.
Megan
This may well be type specific, etc...I can't speak for the 737 but as far as the 777 goes the general principle is to ensure the aircraft is trimmed/flown in such a way as to keep the control wheel centred in straight flight.That's actually the general trimming technique for the aircraft, regardless of engine out or not, and there's a scale on the top of the control wheel hub to help do this. TBH the slip/skid indicator on the PFD (there's no old fashioned ball as in a turn and slip) is not much used. So in short, no you wouldn't be looking to fly with the ball centred and you wouldn't be looking to deliberately fly one wing down on a 777.
Elsewhere on the forum there is a post implying (perhaps to this reader) that an engine out on a 737, 777 etc is flown with the ball centered. Fact, or do you still bank (how many degrees?) towards the live?
Last edited by wiggy; 25th Feb 2017 at 08:09.
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Wiggy:
During my early years on the 727 we had a real turn and bank indicator. That big ball was great for OEI. Then, the FAA deleted the requirement to have that real T&B, so the company removed them. The little ball below the FD-108 attitude indicator was useless, so we had to get used to using the control will to achieve the proper rudder input. That took a bit of getting used to.
During my early years on the 727 we had a real turn and bank indicator. That big ball was great for OEI. Then, the FAA deleted the requirement to have that real T&B, so the company removed them. The little ball below the FD-108 attitude indicator was useless, so we had to get used to using the control will to achieve the proper rudder input. That took a bit of getting used to.
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j.t.:
What about in a Part 25 transport jet OEI where V2 is achieved during rotation and lift-off? We were taught to keep the wings level unless we ran out of rudder. I believe that happened only on our old fleet of Convair 880s.
(a) at much lower than normal speeds (at/near Vmc) one needs to crank in some bank (certification limit is 5 degrees) towards the operating engine(s) to achieve expected handling characteristics. Achieved Vmc is very bank angle dependent. Climb performance is not the name of the game at this sort of speed .. staying right way up is. Indeed, there may well be no climb in this speed region .. the aircraft often will be in a descent.
The best thing since sliced bread was the big ball that popped up in the HUD upon detection if engine loss. Dead cinch to see and relate to flight path and bank angle.
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What about in a Part 25 transport jet OEI where V2 is achieved during rotation and lift-off?
Will depend on the Type, weight and the speed schedules. If you are well above Vmc (as indicated by V1's increasing with weight) it is all pretty straightforward.
For instance, the older 737 classics, at minimum weight, end up Vmc-limited and the V1 failure OEI gyrations in the sim (until the folk up front get on top of things) are a sight to behold.
Like anything, train to meet the need .. for initial commands and intake F/Os, I used to find time to work the folk up to a min V1, max aft CG failure (using the worst engine damage model on the sim), with a min vis situation and a requirement to fly the opposite localiser. Took a few workup runs, naturally, but most were able to end up flying it like it was rails. Thereafter, of course, routine failures were a bit of a yawn for them.
Problem, as I recall (long time since my 727 days) with the FD108 was the small bank angle's driving an ADI response which just confused the issue.
So far as the OP is concerned, though, wings level gives centred ball, a bit of bank angle shifts the ball out to the low side a tad.
The best thing since sliced bread
I'm just jealous that I have never had the opportunity to fly a HUD-equipped machine ... are you out to Avalon next week ?
Will depend on the Type, weight and the speed schedules. If you are well above Vmc (as indicated by V1's increasing with weight) it is all pretty straightforward.
For instance, the older 737 classics, at minimum weight, end up Vmc-limited and the V1 failure OEI gyrations in the sim (until the folk up front get on top of things) are a sight to behold.
Like anything, train to meet the need .. for initial commands and intake F/Os, I used to find time to work the folk up to a min V1, max aft CG failure (using the worst engine damage model on the sim), with a min vis situation and a requirement to fly the opposite localiser. Took a few workup runs, naturally, but most were able to end up flying it like it was rails. Thereafter, of course, routine failures were a bit of a yawn for them.
Problem, as I recall (long time since my 727 days) with the FD108 was the small bank angle's driving an ADI response which just confused the issue.
So far as the OP is concerned, though, wings level gives centred ball, a bit of bank angle shifts the ball out to the low side a tad.
The best thing since sliced bread
I'm just jealous that I have never had the opportunity to fly a HUD-equipped machine ... are you out to Avalon next week ?
Thread Starter
I asked the question after reading an accident report involving a Super King Air 200 where trials were done and produced a ROC of 302 ft/min with 5° of bank into the live engine and 287 ft/min wings level. Does this mean that banking is only important to optimising ROC on FAR 23 types?
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Oh dear ... can you cite the report, please ? It probably warrants a looksee and comment to answer your question in more detail.
produced a ROC of 302 ft/min with 5° of bank into the live engine and 287 ft/min wings level
First up, 5 degrees relates to Vmc i.e., handling rather than performance.
At or around the optimum climb speed, a bank angle of 2-3 degrees (as a general rule) will produce the best result .. I don't know explicitly what the situation is for the KingAir but it will probably be much the same.
Climb performance measured against speed will look a bit like an upturned cup graph. Hence the importance of getting to and maintaining blue line.
Against bank, the graph is a bit more complicated as the direction of bank has a significant effect on slip. However, typically, for the 2-3 degree optimum situation, climb wings level and at 5 degrees should be somewhat similar and slightly less than optimum.
For the figures quoted, they are meaningless unless we know the rest of the test card point story .. speed, technique, etc. At this stage, all they suggest is the truism that climb performance varies with bank angle.
Does this mean that banking is only important to optimising ROC on FAR 23 types?
FAR 23/25, model aircraft, whatever .. all same same. Back in the lower speed end of the envelope, bank critically affects OEI climb performance. Ergo, you can find a bank angle to optimise climb. At higher speeds, the effects are much smaller and, in general, can be ignored. All to do with sideslip angles, both for the Vmc and climb performance case.
produced a ROC of 302 ft/min with 5° of bank into the live engine and 287 ft/min wings level
First up, 5 degrees relates to Vmc i.e., handling rather than performance.
At or around the optimum climb speed, a bank angle of 2-3 degrees (as a general rule) will produce the best result .. I don't know explicitly what the situation is for the KingAir but it will probably be much the same.
Climb performance measured against speed will look a bit like an upturned cup graph. Hence the importance of getting to and maintaining blue line.
Against bank, the graph is a bit more complicated as the direction of bank has a significant effect on slip. However, typically, for the 2-3 degree optimum situation, climb wings level and at 5 degrees should be somewhat similar and slightly less than optimum.
For the figures quoted, they are meaningless unless we know the rest of the test card point story .. speed, technique, etc. At this stage, all they suggest is the truism that climb performance varies with bank angle.
Does this mean that banking is only important to optimising ROC on FAR 23 types?
FAR 23/25, model aircraft, whatever .. all same same. Back in the lower speed end of the envelope, bank critically affects OEI climb performance. Ergo, you can find a bank angle to optimise climb. At higher speeds, the effects are much smaller and, in general, can be ignored. All to do with sideslip angles, both for the Vmc and climb performance case.
Moderator
The data tabulated p19 doesn't have enough explanatory data to draw much in the way of discrete conclusions. However, the numbers trend in a manner one might expect to see.
Certainly, there is not enough data to draw any conclusions regarding specific performance as a function of bank angle
There is no explanation why there is an apparent preoccupation with 5 degrees bank at the climb speed. I'll see if I can find any OEM guidance on the subject. Certainly, I would have expected that the climb target would have required somewhat lesser bank.
What the data do suggest, however, is the folly of homegrown reduced thrust takeoffs (presumably) driven by engine cost considerations but without any thought to weight reductions appropriate to maintaining OEI performance margins.
Certainly, there is not enough data to draw any conclusions regarding specific performance as a function of bank angle
There is no explanation why there is an apparent preoccupation with 5 degrees bank at the climb speed. I'll see if I can find any OEM guidance on the subject. Certainly, I would have expected that the climb target would have required somewhat lesser bank.
What the data do suggest, however, is the folly of homegrown reduced thrust takeoffs (presumably) driven by engine cost considerations but without any thought to weight reductions appropriate to maintaining OEI performance margins.
Thread Starter
The single engine climb charts make no mention of bank, the associated conditions are listed as, max continuous power, flaps up, gear up, prop feathered, with adjustment if ice vanes are extended. Don't have the King Air emergency pages though to see what they say there.
Was just intrigued John as the FAR 23 manuals I've seen make a point about bank in the event of a failure, and they use the 5° figure. Their performance charts even include the 5° bank as one of the associated conditions, unlike the King Air chart. Whether you actually get to climb though is another matter.
Was just intrigued John as the FAR 23 manuals I've seen make a point about bank in the event of a failure, and they use the 5° figure. Their performance charts even include the 5° bank as one of the associated conditions, unlike the King Air chart. Whether you actually get to climb though is another matter.
Moderator
Looking at my file POH (which covers AAV, although at a later amendment status than the mishap) bank guidance is somewhat delightfully vague.
You need to refer to the Safety Information Section for anything of use.
Vmc references are pretty standard ("not more than 5 degrees of bank"). However, for performance climb it gets a tad rubbery. There are references to "aircraft flown at recommended bank angle" under the section on Vyse (but without defining what might be recommended), and "the airplane must be banked about 5 degrees into the live engine" under the section on basic single engine procedures. I guess the poor old pilot needs to be a bit of a mind reader (or do a lot of general research reading).
I would revert to my previous thoughts. Near Vmc target 5 degrees bank into the operating engine while, for Vyse, perhaps 2-3 degrees (if performance is super critical on the day - otherwise wings level) and, for higher speeds, wings level.
Nothing that I can find in the emergency section (Section III).
So far as the run of the mill manuals, one needs to keep in mind the litigious nature of the US environment and a reluctance to provide guidance other than to the extent required by regulation. 5 degrees, at least, is referred to in the Regs.
You need to refer to the Safety Information Section for anything of use.
Vmc references are pretty standard ("not more than 5 degrees of bank"). However, for performance climb it gets a tad rubbery. There are references to "aircraft flown at recommended bank angle" under the section on Vyse (but without defining what might be recommended), and "the airplane must be banked about 5 degrees into the live engine" under the section on basic single engine procedures. I guess the poor old pilot needs to be a bit of a mind reader (or do a lot of general research reading).
I would revert to my previous thoughts. Near Vmc target 5 degrees bank into the operating engine while, for Vyse, perhaps 2-3 degrees (if performance is super critical on the day - otherwise wings level) and, for higher speeds, wings level.
Nothing that I can find in the emergency section (Section III).
So far as the run of the mill manuals, one needs to keep in mind the litigious nature of the US environment and a reluctance to provide guidance other than to the extent required by regulation. 5 degrees, at least, is referred to in the Regs.
Thread Starter
Thanks muchly John, I think that wraps it up. Of the two FAR 23 manuals I have one is of 1979 vintage and the other 1981, a little prior to the sharks getting their teeth into GA in a determined fashion and decimating same, though they've always been there circling.
JT
Typically during certification 5 degrees of bank will be used for Vmc determination to achieve Vmc min. More bank (not permitted) will give an even lower Vmc.
Climb performance speed speed is established by sawtooth climbs bracketing a speed range, then performance is measured at that speed. Invariably this is at 0 degrees sideslip, at the bank angle required for zero sideslip. The bank angles you suggest fit with my experience.
The flight test aircraft will have an alpha/beta probe (angle of incidence/sideslip).
In the real world, in some aircraft zero sideslip is pretty easy to pick, in others very difficult without dedicated instrumentation. Pretty well all conventional jets will have zero aileron hand wheel angle at zero sideslip due to normally strong rolling moment due to sideslip. All bets off for FBW, but one could select the flight control page and adjust rudder until zero aileron angle at zero roll rate is achieved, not that this would be in any way practical. Propellors complicate things by prop wash induced rolling moment.
There may be operational reasons for climbing at other than zero sideslip.
Not meant as an egg sucking lesson but to add to the general conversation.
Have fun at AV.
Typically during certification 5 degrees of bank will be used for Vmc determination to achieve Vmc min. More bank (not permitted) will give an even lower Vmc.
Climb performance speed speed is established by sawtooth climbs bracketing a speed range, then performance is measured at that speed. Invariably this is at 0 degrees sideslip, at the bank angle required for zero sideslip. The bank angles you suggest fit with my experience.
The flight test aircraft will have an alpha/beta probe (angle of incidence/sideslip).
In the real world, in some aircraft zero sideslip is pretty easy to pick, in others very difficult without dedicated instrumentation. Pretty well all conventional jets will have zero aileron hand wheel angle at zero sideslip due to normally strong rolling moment due to sideslip. All bets off for FBW, but one could select the flight control page and adjust rudder until zero aileron angle at zero roll rate is achieved, not that this would be in any way practical. Propellors complicate things by prop wash induced rolling moment.
There may be operational reasons for climbing at other than zero sideslip.
Not meant as an egg sucking lesson but to add to the general conversation.
Have fun at AV.
Last edited by zzuf; 26th Feb 2017 at 08:55. Reason: typo
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Good sir, we'll have one (or three) for you at the symposium ..
in others very difficult without dedicated instrumentation
Bellerophon posted a pic of the Concorde gauge .. talk about snazzy.
There may be operational reasons for climbing at other than zero sideslip.
Apart from workload and things like the FD108 limitations mentioned earlier ... and only showing my ignorance here .. can you elaborate ?
in others very difficult without dedicated instrumentation
Bellerophon posted a pic of the Concorde gauge .. talk about snazzy.
There may be operational reasons for climbing at other than zero sideslip.
Apart from workload and things like the FD108 limitations mentioned earlier ... and only showing my ignorance here .. can you elaborate ?
I was thinking of those cases where the trainers have decided wings level or skid ball central is an easier option than trying to determine the required bank angle and those steam driven attitude indicators which try to erect to a "false" vertical at small bank angles (as you mentioned).
When manoeuvres are required it is very difficult to maintain zero sideslip even with beta indicator - constant rudder force seems ok (at constant CAS). I know this wasn't part of the original thread subject but may be part of an escape flight path.
When I did my Canberra training (nearly 50 years ago) the RAAF was firmly skid ball central at all times. I clearly recall turning base, asymmetric, with almost full left rudder and the aileron hand wheel bumping the right stop in turbulence! I suspect this technique may have contributed to at least one loss of control incident. The fix was back off half the rudder deflection, and the ailerons returned to about neutral - who cares where the skid ball was!
Later at ETPS an instrumented Canberra was available to clearly demonstrate the folly of the RAAF technique.
I believe the RAF lost a Hunter which had an asymmetric external fuel tank jettison, the pilot was told "simple, just keep the ball centered", I think it was in manual reversion with limited aileron authority. Anyway it departed rolling rapidly in the direction of the applied rudder.
When manoeuvres are required it is very difficult to maintain zero sideslip even with beta indicator - constant rudder force seems ok (at constant CAS). I know this wasn't part of the original thread subject but may be part of an escape flight path.
When I did my Canberra training (nearly 50 years ago) the RAAF was firmly skid ball central at all times. I clearly recall turning base, asymmetric, with almost full left rudder and the aileron hand wheel bumping the right stop in turbulence! I suspect this technique may have contributed to at least one loss of control incident. The fix was back off half the rudder deflection, and the ailerons returned to about neutral - who cares where the skid ball was!
Later at ETPS an instrumented Canberra was available to clearly demonstrate the folly of the RAAF technique.
I believe the RAF lost a Hunter which had an asymmetric external fuel tank jettison, the pilot was told "simple, just keep the ball centered", I think it was in manual reversion with limited aileron authority. Anyway it departed rolling rapidly in the direction of the applied rudder.
Last edited by zzuf; 26th Feb 2017 at 10:33. Reason: typo