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A320 Single Engine Missed Approach

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A320 Single Engine Missed Approach

Old 28th Mar 2023, 11:51
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api
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A320 Single Engine Missed Approach

Dear all,

I have a question regarding the missed approach procedure Engine Out. Specifically, when do the thrust levers go from TOGA to MCT.
Say i am coming in for the approach single engine. On the approach plate i learn that the missed approach gradient is a standard 2.5% and go around altitude 3000. I decide i want to follow the standard missed approach instead of a custom EOSID.
What i understand from some airlines i asked: at acceleration altitude (std 1500) the crew levels the aircraft for acceleration and cleaning the drag and once done, continue in open climb and promptly set thrust to MCT.
My reasoning says that once you do all that below missed approach altitude then you no longer can be sure of the approach climb gradient you have calculated in the performance calculations software of your choosing.

Any insights on the matter is most welcome, hopefully with a corresponding page in the FCOM, FCTM, ICAO Doc or a paraphrasing from an OMA. Only then i might be able to talk sense to someone in my company….


p.s.
Any idea where i can find the manual for the Flysmart Landing/Takeoff app?
Cheers
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Old 28th Mar 2023, 12:54
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You are mixing up two things. The EOSID is the case where you have an engine failure at V1, on the ground, in a takeoff. It includes an acceleration altitude.

In a missed approach you are much higher a the start of the go-around and in many cases climbing over the runway. You can use the performance tool to check the single engine climb gradient, but there is no acceleration altitude specified. The acceleration altitude is either final go-around altitude, although some companies will allow acceleration once above MSA (and remaining in the vicinity of the airport).

If the single-engine go-around performance is limiting, some companies then specify you can always opt for the specific EOSID, but this is a little grey zone as you are mixing up two different aircraft configurations (TO vs go-around config). Ie on 737 takeoff can be flaps (1)/5/... and go-around could be flaps 15 single engine (engine failure on final).
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Old 28th Mar 2023, 16:12
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There's no acceleration segment in missed approach procedure. Unless an operator has specifically checked out that acceleration at certain altitude can meet terrain clearance and gradient requirement you should be climbing to missed approach altitude before accelerating. And after level of once aircraft is cleaned and climb is resumed thrust is brought to MCT. Takeoff and missed approach paths are not exactly same. So EOSID may or may not be applicable. It will depend on the particular geographical situation.
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Old 28th Mar 2023, 18:38
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BraceBrace Yes, i know i am mixing up the EOSID where it does not naturally belong, but as you said yourself:
some companies then specify you can always opt for the specific EOSID, but this is a little grey zone
And my company just loves grey zones. Here i am trying to figure out the hard truth.

vilas
you should be climbing to missed approach altitude before accelerating. And after level of once aircraft is cleaned and climb is resumed thrust is brought to MCT
Thats what I’ve been taught in my TR and so i started my crusade against all the TRE/TRI and chief pilot.

So can you two back this with any written proof?
I have tried the FCTM and FCOM and ICAO Doc 8168. I did not find any smoking gun. Just some vague things.

​​​​​​​cheers,
​​​​​​​
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Old 28th Mar 2023, 20:40
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First of all, all PANS-OPS procedures are designed for all engines operative (8168 - 1.1.2)

Regulatory approach climb gradient (engine out) is 2,1% (2,5% for Cat 2/3) and not 2,5% as for all engine ops, so even if you follow published missed approach procedure (2,5%) there is a risk of busting obstacle clearance

As Vilas said, missed approach is designed without acceleration segment (there is a nice picture of it in 8168)

Taking all this into account, it would be unwise to accelerate before missed app alt (or MSA if lower), unless your company has specific performance calculations or if you are not 110% sure that you will be able to accelerate and still be above required gradient during acceleration
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Old 28th Mar 2023, 22:46
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Originally Posted by api
Dear all,

I have a question regarding the missed approach procedure Engine Out. Specifically, when do the thrust levers go from TOGA to MCT.
Say i am coming in for the approach single engine. On the approach plate i learn that the missed approach gradient is a standard 2.5% and go around altitude 3000. I decide i want to follow the standard missed approach instead of a custom EOSID.
What i understand from some airlines i asked: at acceleration altitude (std 1500) the crew levels the aircraft for acceleration and cleaning the drag and once done, continue in open climb and promptly set thrust to MCT.
My reasoning says that once you do all that below missed approach altitude then you no longer can be sure of the approach climb gradient you have calculated in the performance calculations software of your choosing.

Any insights on the matter is most welcome, hopefully with a corresponding page in the FCOM, FCTM, ICAO Doc or a paraphrasing from an OMA. Only then i might be able to talk sense to someone in my company….


p.s.
Any idea where i can find the manual for the Flysmart Landing/Takeoff app?
Cheers
Ref. 8168 chapter 6.1

6.1.2 Phases of missed approach segment

In principle the missed approach segment starts at the MAPt and includes the following three phases (see Figure I-4-6-4):

a) initial phase — begins at the earliest MAPt, and extends until the Start of Climb (SOC);

b) intermediate phase — extends from the SOC to the point where 50 m (164 ft) (Cat H, 40 m (132 ft)) obstacle clearance is first obtained and can be maintained; and

c) final phase — extends to the point at which a new approach, holding or return to en-route flight is initiated. Turns may be carried out during this phase.

Climb gradient in the final phase: The criteria of the intermediate phase apply. (i.e. 2.5% or whatever it is specified)

Bottom line: you will always have to maintain some sort of positive climb gradient up to the go around altitude or at least the MSA. Check Your OM-A Chapter 8 regarding one engine out procedures and look for the requirements set by your company regarding the missed approach OEI. It should tell you what to do and when.


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Old 29th Mar 2023, 03:29
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Another pill:

PANS-OPS 3 approach charts were designed with an acceleration segment depicted in the missed approach procedure. If you happen to be flying one of those charts you can accelerate and clean the airplane as per the procedure. For the rest of approach plates that are PANS-OPS, there is no acceleration segment included, so if you level off and accelerate, you will be doing so without knowing exactly if you are hitting the ground clearance slope.

And, that ground clearance slope that you are required to maintain always, is calculated from the MDA or DA. If you do the go around below minimum, there is no approach gradient chart to check your perfomance with one engine, so you are required to follow the engine out procedure (even with all engines operating), to make sure that if you lose an engine you'll never hit the ground clearance slope.

There are airlines that require pilots to follow the engine out procedure when doing the go around above minimum and with all engines operating, if the OAT is above the flat rate temperature of the engine. The reasoning is that above that temperature, the engine doesn't produce TOGA thrust anymore even if the thrust levers are in TOGA (flat rated engines produce full TOGA thrust up to a certain OAT, after which the output thrust starts reducing) and therefore the performance doesn't comply with the requirements.

I believe all this is in the 8168 ICAO document.
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Old 29th Mar 2023, 07:09
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Toga limitation

Thank you all for your time and effort.
I just wish Airbus had wrote something less confusing than:
”At the engine out acceleration altitude, apply the same technique as described earlier” FCTM-PR-AEP-ENG-ONE ENG INOP GA
It seems to throw people off in my company.

Also;
How can i be sure that i do not infringe the 10min TOGA limitation if i follow the published missed approach (and so i reduce thrust at missed approach altitude)?

Last edited by api; 29th Mar 2023 at 07:56.
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Old 29th Mar 2023, 08:12
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Originally Posted by api
Thank you all for your time and effort.
I just wish Airbus had wrote something less confusing than:
”At the engine out acceleration altitude, apply the same technique as described earlier” FCTM-PR-AEP-ENG-ONE ENG INOP GA
It seems to throw people off in my company.

Also;
How can i be sure that i do not infringe the 10min TOGA limitation if i follow the published missed approach (and so i reduce thrust at missed approach altitude)?
Ten minutes should meet any MSA/ Missed Approach altitude.
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Old 29th Mar 2023, 08:46
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You know by using a timer... But even with 10 minutes... try Geneva at maximum landing weight.

Just two remarks: the calculations we do are based on a set of rules, minimum requirements, etc... but they are never "reality". The EOSID is a calculation based on an engine failure close at V1. It is not an engine failure at rotation. It is not an engine failure in your first turn. It is not an engine failure at the current actual weight of the aircraft, your aircraft will give more than regulations in many cases. There is a difference between flight preparation regulations and SOP's.

Also - even though many are totally against this practice for very good reasons (negative training) - some instructors might ask you to "deviate" from what you would do in real life to save time in the simulator. Engine out practice is usually one of those cases, where, to save time, quick accelerations in a single engine go-around are accepted to avoid waisting too much time. In some companies, the amount of excercices that need to be carried out in the simulator is becoming really a sad burden for the training people.
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Old 29th Mar 2023, 10:36
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Originally Posted by api
Dear all,

I have a question regarding the missed approach procedure Engine Out. Specifically, when do the thrust levers go from TOGA to MCT.
Say i am coming in for the approach single engine. On the approach plate i learn that the missed approach gradient is a standard 2.5% and go around altitude 3000. I decide i want to follow the standard missed approach instead of a custom EOSID.
What i understand from some airlines i asked: at acceleration altitude (std 1500) the crew levels the aircraft for acceleration and cleaning the drag and once done, continue in open climb and promptly set thrust to MCT.
My reasoning says that once you do all that below missed approach altitude then you no longer can be sure of the approach climb gradient you have calculated in the performance calculations software of your choosing.

Any insights on the matter is most welcome, hopefully with a corresponding page in the FCOM, FCTM, ICAO Doc or a paraphrasing from an OMA. Only then i might be able to talk sense to someone in my company….


p.s.
Any idea where i can find the manual for the Flysmart Landing/Takeoff app?
Cheers
Same problem here… nothing written in OM-A or SOPS and everyone accelerates at a different stage during OEI go around…
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Old 29th Mar 2023, 11:24
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At a risk of stirring the pot somewhat and upsetting various people, we need to keep in mind that the "rules" are based on history and history-based "reasonable" assumptions. The rules do not provide an absolute guarantee that all will go well on every occasion.

So, what to do ?

The poor cousin end of the market has a tendency to suck in some air between clenched teeth and apply whatever protocols seem to fit, SOP or whatever and, often, without much independent thought being given to the problem. The sensibly risk aware operator (and pilot, if you don't have a serious operator behind you) will make sure that the dice are loaded your way by running appropriate calculations in the design office. This, really, is just basic corporate risk management.

If the obstacle profile for the runway considered to apply for the miss is very benign, then the normal SOP will not have a great problem in general. For many areas, this covers a large proportion of the extant runways.

However, as the obstacle problems increase, there is a sensible need to do some ops engineering type sums to make sure that you know what you might be facing for the dark night situation when it all goes awry. Do you have all the data you might like to have ? Generally, not. But all is not lost.

There is no easy way out of the dilemma - you need the obstacle data, you need the AFM, and you need the technical skills and time to run some analyses to figure some weight limits and flight paths appropriate for the situation. Presuming you already have assessed the obstacles and have run any appropriate OEI escape plans for the runway, you should have enough obstacle data available to run the sums on a quasi takeoff process using the available AFM performance data and, if necessary, some simple flight test data to fill in any missing bits for the office work. It's not rocket science but it does take a bit of knowledge and understanding and the will to spend some money on the work up to provide the crew with useful and sensible data for the miss planning.

Some of us take considerable pains to get this stuff sensibly right, others tend to rely on motherhood statements and winging things on the fly. I know which approach I favour.

A few personal thoughts on previous post comments.

when do the thrust levers go from TOGA to MCT

If it's a planned for situation, much the same as for takeoff and you plan the story to meet the AFM engine limitations. If you are in some nasty emergency situation where pre-planning couldn't have been done, I don't think you need to worry too much about running a bit over the time limits if you have a reasonable need to do so. Maintenance might not include you on their Christmas card list for the year but that's the least of your worries.

I decide i want to follow the standard missed approach instead of a custom EOSID.

Bit late, methinks, to be making those sort of decisions in the heat of the moment. That is the sort of stuff you need to think about at pre-flight planning or, if you are in an emergency divert situation, during the divert cruise.

In a missed approach you are much higher a the start of the go-around

Perhaps, perhaps not. How about if you are faced with a miss from the flare or very late final ? And you still have to figure the distance needed to reconfigure to a takeoff situation where you can better fit the performance to the obstacle profile(s). Always keeping in mind the main mantra - "don't crash".

There's no acceleration segment in missed approach procedure

Which is why you need to run an obstacle analysis. While this can be done with gradients, and with some mathematical pushing and shoving, it is much easier to use a discrete obstacle analysis ie where you know the obstacle x, y, z data.

So can you two back this with any written proof ?

I doubt it very much. There is just too much variation to countenance the motherhood approach.

If you happen to be flying one of those charts you can accelerate and clean the airplane as per the procedure.

Not really. There is no "one size fits all" in the reconfiguration. Perhaps you might like to compare several Types for third segment distance data. Do include the DC9 in that selection ...


Now, has anyone thought much about this on a day where the airspace is filled to the brim with turbulence ?
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Old 29th Mar 2023, 14:49
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Originally Posted by john_tullamarine
At a risk of stirring the pot somewhat and upsetting various people, we need to keep in mind that the "rules" are based on history and history-based "reasonable" assumptions. The rules do not provide an absolute guarantee that all will go well on every occasion.

So, what to do ?

The poor cousin end of the market has a tendency to suck in some air between clenched teeth and apply whatever protocols seem to fit, SOP or whatever and, often, without much independent thought being given to the problem. The sensibly risk aware operator (and pilot, if you don't have a serious operator behind you) will make sure that the dice are loaded your way by running appropriate calculations in the design office. This, really, is just basic corporate risk management.

If the obstacle profile for the runway considered to apply for the miss is very benign, then the normal SOP will not have a great problem in general. For many areas, this covers a large proportion of the extant runways.

However, as the obstacle problems increase, there is a sensible need to do some ops engineering type sums to make sure that you know what you might be facing for the dark night situation when it all goes awry. Do you have all the data you might like to have ? Generally, not. But all is not lost.

There is no easy way out of the dilemma - you need the obstacle data, you need the AFM, and you need the technical skills and time to run some analyses to figure some weight limits and flight paths appropriate for the situation. Presuming you already have assessed the obstacles and have run any appropriate OEI escape plans for the runway, you should have enough obstacle data available to run the sums on a quasi takeoff process using the available AFM performance data and, if necessary, some simple flight test data to fill in any missing bits for the office work. It's not rocket science but it does take a bit of knowledge and understanding and the will to spend some money on the work up to provide the crew with useful and sensible data for the miss planning.

Some of us take considerable pains to get this stuff sensibly right, others tend to rely on motherhood statements and winging things on the fly. I know which approach I favour.

A few personal thoughts on previous post comments.

when do the thrust levers go from TOGA to MCT

If it's a planned for situation, much the same as for takeoff and you plan the story to meet the AFM engine limitations. If you are in some nasty emergency situation where pre-planning couldn't have been done, I don't think you need to worry too much about running a bit over the time limits if you have a reasonable need to do so. Maintenance might not include you on their Christmas card list for the year but that's the least of your worries.

I decide i want to follow the standard missed approach instead of a custom EOSID.

Bit late, methinks, to be making those sort of decisions in the heat of the moment. That is the sort of stuff you need to think about at pre-flight planning or, if you are in an emergency divert situation, during the divert cruise.

In a missed approach you are much higher a the start of the go-around

Perhaps, perhaps not. How about if you are faced with a miss from the flare or very late final ? And you still have to figure the distance needed to reconfigure to a takeoff situation where you can better fit the performance to the obstacle profile(s). Always keeping in mind the main mantra - "don't crash".

There's no acceleration segment in missed approach procedure

Which is why you need to run an obstacle analysis. While this can be done with gradients, and with some mathematical pushing and shoving, it is much easier to use a discrete obstacle analysis ie where you know the obstacle x, y, z data.

So can you two back this with any written proof ?

I doubt it very much. There is just too much variation to countenance the motherhood approach.

If you happen to be flying one of those charts you can accelerate and clean the airplane as per the procedure.

Not really. There is no "one size fits all" in the reconfiguration. Perhaps you might like to compare several Types for third segment distance data. Do include the DC9 in that selection ...


Now, has anyone thought much about this on a day where the airspace is filled to the brim with turbulence ?
Some points to note:
  • 10 minutes TOGA//takeoff-thrust is a hard limit for OEI, you can damage a good engine if you exceed. It is not wise even by a few minutes.
  • If you encounter an engine failure on approach there is no EOSID, you have to follow the missed approach procedure. The question is good one, does it take into account the climb gradient to ensure obstacle clearance?
Rest I agree with you John, great analysis. Great question also from the poster very curious about this one.
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Old 29th Mar 2023, 14:59
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You know by using a timer... But even with 10 minutes... try Geneva at maximum landing weight.
​​​​​​​If ten minutes is going to be an issue then shouldn't something planned before approach or takeoff itself?
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Old 29th Mar 2023, 15:13
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Originally Posted by vilas
If ten minutes is going to be an issue then shouldn't something planned before approach or takeoff itself?
Exactly.
Flysmart offers the possibility to amend the GA Gradient as required and to amend the target altitude till which said gradient must be maintained, although this last function has to be activated upon request by the operator.
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Old 29th Mar 2023, 15:44
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Originally Posted by BraceBrace
You know by using a timer... But even with 10 minutes... try Geneva at maximum landing weight.
Surely you understand why using the timer is not a viable option. (Stop calling me Shirley!)
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Old 30th Mar 2023, 06:20
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Talking

Originally Posted by k.swiss
Some points to note:
  • 10 minutes TOGA//takeoff-thrust is a hard limit for OEI, you can damage a good engine if you exceed. It is not wise even by a few minutes.
  • If you encounter an engine failure on approach there is no EOSID, you have to follow the missed approach procedure. The question is good one, does it take into account the climb gradient to ensure obstacle clearance?
Rest I agree with you John, great analysis. Great question also from the poster very curious about this one.
What you say is almost the full story, but not quite, it arises out of §33.27.... and that is the way the world has been. Until now... the modification I am doing an STC on large engines, coming out of the TFE731 tests gives max rated TO thrust levels while the engine is below MCT RPM, EGT and fuel flow. (Turns out, there are nice things that can be done with aero).

Can you run the engine at full rating in an emergency for longer than 5 minute or 10 minutes? The qualification of the engine required demonstration to show there is zero damage in such a case, and if there was any damage, then the engine has to operate for another 5 minutes after the time that damage occurs. For the demonstration, it is not known and is not required to be known that the engine was run for more, so at that time limit, it can only be said that it is the required test point, after which, you are on your own. However, the test point is not at the RPM and EGT and thrust of TO/GA, it is at 120% RPM related to that point, and that is not a trivial matter; that is, your 100% N1 limit, the engine has to do the test at 120% N1, and that then means the thrust output is between 1.4-1.44x the rated thrust, the EGT will increase by the relationship it has to N2 (N3) and so has fuel flow, that is, your EGT will be far higher than the limit EGT that the engine has been tested to.

Will the engine fail at 5:01 at MAX TO/GA thrust? No. Will it need to be inspected, yes, it exceeded a limit. Some engines have a designated time exceedance inspection program, some do not. Coming off the stop is desirable though as you have one engine between your beer and being a glider.

watch the video on www.delta-burn.com which shows a very simple but repeatable test. The ground test matches the flight test quite accurately.

So, in this case, the time limit for the thrust level which is predicated on the margins that arise from the § 33.27 (a) Turbine, compressor, fan, and turbosupercharger rotor overspeed. requirement. From that, the question is what can you run a modified engine at... as modified, we are always around 10% lower RPM and 140C lower EGT, and 30% TSFC better than when the engine came out of the factory. If that sounds odd, know that for the pleasure of paying for MSP GOLD, the engine in this video came back after overhaul with a ZERO EGT margin, thanks! In the video, it is putting out more thrust than the standard engine... so... what is it's max TO thrust time limit? It never gets to Max EGT, (not because of the efforts of an MSP GOLD MPI). If run at normal target RPM for the rated thrust, which is say, 98.1%, 3,700lbf, it gets 5,250lbf out of it, which is a nice bump but not for normal operations. When pulling the RPM back equal thrust occurs with a >9% lower N1, which is lower that normal cruise RPM, an EGT that drops by 140C, 740C vs 885C and so what is the time limit on the engine? Outcome? This engine gets sea level TO thrust to 9000' sea level max CLB to 16,000' and above that it has 2 times the excess thrust that the standard engine gives. Alternatively, and as they are my engines, they run slower, colder and cleaner, and with lower fuel burn, and the range of the aircraft goes up. 50% up.

The STC program for the first engines has started up, this is straightforward on the engine, it is an irritant for Boeing architecture, but mainly simple for the Airbus, and the EPR target aircraft. N1 target is fine for manual thrust systems, otherwise G/A can be interesting.

For a normal case, 33.27 gives the time constraints and the qualification that has to be met, it just happens that the engine STC that I am doing kind of messes with the mind somewhat.

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Old 30th Mar 2023, 19:56
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Originally Posted by fdr
What you say is almost the full story, but not quite, it arises out of §33.27.... and that is the way the world has been. Until now... the modification I am doing an STC on large engines, coming out of the TFE731 tests gives max rated TO thrust levels while the engine is below MCT RPM, EGT and fuel flow. (Turns out, there are nice things that can be done with aero).

Can you run the engine at full rating in an emergency for longer than 5 minute or 10 minutes? The qualification of the engine required demonstration to show there is zero damage in such a case, and if there was any damage, then the engine has to operate for another 5 minutes after the time that damage occurs. For the demonstration, it is not known and is not required to be known that the engine was run for more, so at that time limit, it can only be said that it is the required test point, after which, you are on your own. However, the test point is not at the RPM and EGT and thrust of TO/GA, it is at 120% RPM related to that point, and that is not a trivial matter; that is, your 100% N1 limit, the engine has to do the test at 120% N1, and that then means the thrust output is between 1.4-1.44x the rated thrust, the EGT will increase by the relationship it has to N2 (N3) and so has fuel flow, that is, your EGT will be far higher than the limit EGT that the engine has been tested to.

Will the engine fail at 5:01 at MAX TO/GA thrust? No. Will it need to be inspected, yes, it exceeded a limit. Some engines have a designated time exceedance inspection program, some do not. Coming off the stop is desirable though as you have one engine between your beer and being a glider.

watch the video on www.delta-burn.com which shows a very simple but repeatable test. The ground test matches the flight test quite accurately.

So, in this case, the time limit for the thrust level which is predicated on the margins that arise from the § 33.27 (a) Turbine, compressor, fan, and turbosupercharger rotor overspeed. requirement. From that, the question is what can you run a modified engine at... as modified, we are always around 10% lower RPM and 140C lower EGT, and 30% TSFC better than when the engine came out of the factory. If that sounds odd, know that for the pleasure of paying for MSP GOLD, the engine in this video came back after overhaul with a ZERO EGT margin, thanks! In the video, it is putting out more thrust than the standard engine... so... what is it's max TO thrust time limit? It never gets to Max EGT, (not because of the efforts of an MSP GOLD MPI). If run at normal target RPM for the rated thrust, which is say, 98.1%, 3,700lbf, it gets 5,250lbf out of it, which is a nice bump but not for normal operations. When pulling the RPM back equal thrust occurs with a >9% lower N1, which is lower that normal cruise RPM, an EGT that drops by 140C, 740C vs 885C and so what is the time limit on the engine? Outcome? This engine gets sea level TO thrust to 9000' sea level max CLB to 16,000' and above that it has 2 times the excess thrust that the standard engine gives. Alternatively, and as they are my engines, they run slower, colder and cleaner, and with lower fuel burn, and the range of the aircraft goes up. 50% up.

The STC program for the first engines has started up, this is straightforward on the engine, it is an irritant for Boeing architecture, but mainly simple for the Airbus, and the EPR target aircraft. N1 target is fine for manual thrust systems, otherwise G/A can be interesting.

For a normal case, 33.27 gives the time constraints and the qualification that has to be met, it just happens that the engine STC that I am doing kind of messes with the mind somewhat.
OK fantastic summary, thank you for taking the time to explain it at such a level! I won't argue with that.

Extremely insightful!
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Old 31st Mar 2023, 01:43
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Originally Posted by sonicbum
Exactly.
Flysmart offers the possibility to amend the GA Gradient as required and to amend the target altitude till which said gradient must be maintained, although this last function has to be activated upon request by the operator.
Now I'm curious. So it makes sure you reach the target altitude & accelerate within the 10 minutes before setting MCT or it gives you a warning you need a better climb gradient? I'm just curious to know how you make sure everything is done within 10 minutes.

On the Boeing OPT there is the standard MACG check where we can adapt the MACG to check single engine performance on the missed approach. But there is nowhere a check that verifies how long it takes to fly the full procedure up to clean-up. I might be missing something...
BraceBrace is offline  
Old 31st Mar 2023, 02:51
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I might be missing something...

If you run it as a piecemeal analysis, you end up with the time to wherever and then you can iterate the process to figure what you can and can't do. No different to a normal T/O analysis, just a bit more involved in the detail.
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