EGT OVERLIMIT at T/O: continue flight?
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EGT OVERLIMIT at T/O: continue flight?
Under particular conditions (hot-heavy-full thrust) the EGT can get very close to the limit during the takeoff roll, and at times exceed it.
Should this happen between V1 and 400ft, there's a time period of about 15 seconds during which the EGT stays above the limit, before doing the appropriate recall items.
After such an occurence, do you have any sort of guidelines about continuing the flight to destination, or returning to the point of departure?
Example: CFM56 3C1, EGT stays at 940° for 15 seconds.
Using common sense, one could say that a few degrees above max won't harm the engines, besides shortening their long term life, but...
How can you really know?
Is it still safe to fly like that? What if instead of 940° you reached 960°?
I've requested to our technicians their tolerance charts, hope they will not forget...
Thak you.
Should this happen between V1 and 400ft, there's a time period of about 15 seconds during which the EGT stays above the limit, before doing the appropriate recall items.
After such an occurence, do you have any sort of guidelines about continuing the flight to destination, or returning to the point of departure?
Example: CFM56 3C1, EGT stays at 940° for 15 seconds.
Using common sense, one could say that a few degrees above max won't harm the engines, besides shortening their long term life, but...
How can you really know?
Is it still safe to fly like that? What if instead of 940° you reached 960°?
I've requested to our technicians their tolerance charts, hope they will not forget...
Thak you.
Warning Toxic!
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You have exceeded an aircraft limitation, therefore you cannot continue. You do not have the option of deciding 'it was only by a little bit'. If it was anything more than momentary, you should complete the Surge/Limit/Stall checklist then decide your next course of action. It is for others to decide whether to pull the engine, you to land without delay (on a twin).
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Under particular conditions (hot-heavy-full thrust) the EGT can get very close to the limit during the takeoff roll, and at times exceed it.
Should this happen between V1 and 400ft, there's a time period of about 15 seconds during which the EGT stays above the limit, before doing the appropriate recall items.
After such an occurence, do you have any sort of guidelines about continuing the flight to destination, or returning to the point of departure?
Example: CFM56 3C1, EGT stays at 940° for 15 seconds.
Using common sense, one could say that a few degrees above max won't harm the engines, besides shortening their long term life, but...
How can you really know?
Is it still safe to fly like that? What if instead of 940° you reached 960°?
I've requested to our technicians their tolerance charts, hope they will not forget...
Thak you.
Should this happen between V1 and 400ft, there's a time period of about 15 seconds during which the EGT stays above the limit, before doing the appropriate recall items.
After such an occurence, do you have any sort of guidelines about continuing the flight to destination, or returning to the point of departure?
Example: CFM56 3C1, EGT stays at 940° for 15 seconds.
Using common sense, one could say that a few degrees above max won't harm the engines, besides shortening their long term life, but...
How can you really know?
Is it still safe to fly like that? What if instead of 940° you reached 960°?
I've requested to our technicians their tolerance charts, hope they will not forget...
Thak you.
Does this question have something to do with a recent Safety Reccomendation issued by the Flight Safety Dept of your company?
Anyway very nice question.
In my opinion when this happens on a CFM-56 @ 22k it is time to change it, so as you have exeeded the a limit as Rainboe was saying apply the appropriete checklist, come back and give the company the opportunity of thanking you for you professionalism.
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EGT
Gentlemen,
I hesitate to comment unless I have reference to provide. In this case, I haven't the manuals with me.
However, as jet engines age, the "EGT Margin" reduces. At some point in the engine's life, it is, in fact, possible to slightly overtemp. This is normal.
Yes...what you just read is correct....to overtemp on takeoff is, in some cases and from an engineer's view point, 'normal'.
Again, this will occur when a jet engine ages. However, everything depends on by how much the EGT has been exceeded and for how long.
In some cases, e.g. slightly over the limit and for just a few moments, there will be no maintenance action necessary. In other cases, the engine may need to be changed.
There exist graphs showing all of this.
In all cases, the action demanded from the pilot is to follow SOP for EGT over limit.
Obviously, if engines overtemp on takeoff, they are due maintenance, overhaul, replacement...for that reason alone. This means that it's a tired engine, and it's due for some T.L.C. Not necessarily for the overtemp occurrance...but, for the reason the engines overtemp in the first place.
PantLoad
I hesitate to comment unless I have reference to provide. In this case, I haven't the manuals with me.
However, as jet engines age, the "EGT Margin" reduces. At some point in the engine's life, it is, in fact, possible to slightly overtemp. This is normal.
Yes...what you just read is correct....to overtemp on takeoff is, in some cases and from an engineer's view point, 'normal'.
Again, this will occur when a jet engine ages. However, everything depends on by how much the EGT has been exceeded and for how long.
In some cases, e.g. slightly over the limit and for just a few moments, there will be no maintenance action necessary. In other cases, the engine may need to be changed.
There exist graphs showing all of this.
In all cases, the action demanded from the pilot is to follow SOP for EGT over limit.
Obviously, if engines overtemp on takeoff, they are due maintenance, overhaul, replacement...for that reason alone. This means that it's a tired engine, and it's due for some T.L.C. Not necessarily for the overtemp occurrance...but, for the reason the engines overtemp in the first place.
PantLoad
Over the limit calls for recall actions, end of story. "Interpretation" is in this case not our job.
If the engine reaches 726°C during start, it's not something too "interpret" too. It's simply not allowed.
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Indeed, I don't see the point in establishing specific limits and then decide to "interpret" the values to see if we follow procedures or not. As said previously, EGT during cannot reach the limiting values, if they do, it means they are pushed too far. It will not harm them, maybe not... but maybe it will... who will say? You are talking about something very critical here: even though it is EGT, it is a representation of a high pressure turbine temperature, a very critical point in a jet engine.
Over the limit calls for recall actions, end of story. "Interpretation" is in this case not our job.
If the engine reaches 726°C during start, it's not something too "interpret" too. It's simply not allowed.
Over the limit calls for recall actions, end of story. "Interpretation" is in this case not our job.
If the engine reaches 726°C during start, it's not something too "interpret" too. It's simply not allowed.
now the question is, you have done your recall actions and everything is back to normal.
The checklist doesn't specifically say "Plan to land at the nearest suitable airport"
What would you do? come back or continue?
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A question to those who said "return and land without delay." Would you be so keen to get the aircraft back on the ground that you would be prepared to exceed a second limit (max landind weight) in order to do so?
Personally I would not land over weight unless the engine was looking realy sick, on the other hand I would not cross the Atlantic with it either.
Just food for thought.
Personally I would not land over weight unless the engine was looking realy sick, on the other hand I would not cross the Atlantic with it either.
Just food for thought.
I've had this happen on several occasions with hot/high/heavy departures. Each time we've contacted engineering who downloaded the relevant data straight away by satellite link and advised on a course of action - for me it has always been "Continue and we will monitor".
I do not possess the technical knowledge to decide whether the engine has become unsafe to operate - I rely on qualified advisors for that. If, after t/o, it is running OK and the vital parameters are stable within the specified limits, then I don't have a problem, even if there has been an 'exceedence' of some kind. If the engine subsequently fails in flight, then I'll cope with that when it happens; so far so good...
I do not possess the technical knowledge to decide whether the engine has become unsafe to operate - I rely on qualified advisors for that. If, after t/o, it is running OK and the vital parameters are stable within the specified limits, then I don't have a problem, even if there has been an 'exceedence' of some kind. If the engine subsequently fails in flight, then I'll cope with that when it happens; so far so good...
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EGT OVERLIMIT at T/O: continue flight?
Dear Paolo
We all know that SAFETY of FLIGHT is Paramount important; and then after follow: regularity, passengers comfort, and flight's economy.
According to what You wrote I understand that in Your case one of the engines EGT rose above the T.O. limit for a certain amount of time. For me it doesn't matter how much and how long it has been, that engine has to be checked ASAP. It's like when a woman looses her virginity, it's for ever.
By the way we know that according to the QRH You can continue Your flight at reduced thrust if retarding the throttle all parameters remain within the limits.
How long?...
You don't mention neither the meteo conditions (at departure, destination and alternate airports), nor the sector involved (availability of route-alternate airport and the like), and the aircraft weight relating to MLW.
But I can suppose that at least the weather was not a factor, excepted the high OAT. However if the aircraft weight was above MLW You had anyhow to wait for it in flight.
So I should say:... as long as it takes to proceed to the first suitable airport where the aircraft can be inspected and passengers reprotected.
Best regards
DOVE
P.S.
Did it happen in the past?
And were the consequences unhappy for one of the involved crew members?
We all know that SAFETY of FLIGHT is Paramount important; and then after follow: regularity, passengers comfort, and flight's economy.
According to what You wrote I understand that in Your case one of the engines EGT rose above the T.O. limit for a certain amount of time. For me it doesn't matter how much and how long it has been, that engine has to be checked ASAP. It's like when a woman looses her virginity, it's for ever.
By the way we know that according to the QRH You can continue Your flight at reduced thrust if retarding the throttle all parameters remain within the limits.
How long?...
You don't mention neither the meteo conditions (at departure, destination and alternate airports), nor the sector involved (availability of route-alternate airport and the like), and the aircraft weight relating to MLW.
But I can suppose that at least the weather was not a factor, excepted the high OAT. However if the aircraft weight was above MLW You had anyhow to wait for it in flight.
So I should say:... as long as it takes to proceed to the first suitable airport where the aircraft can be inspected and passengers reprotected.
Best regards
DOVE
P.S.
Did it happen in the past?
And were the consequences unhappy for one of the involved crew members?
Last edited by DOVES; 1st Sep 2006 at 08:16.
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No Problem!
The Maintenance Manual said:
On airplanes with EGT transitory overtemperature capability or Service Bulletin, no maintenance action is necessary when the maximum EGT is between 930 and 940 degrees C for less than 20 seconds when takeoff or go around power is set. Refer to Boeing Service Letter 737-SL-72-006 for more information.
Continue flight but ...
The Maintenance Manual said:
If the EGT exceedance was 5 seconds or more in Area C you must remove the engine for an overtemperature inspection before the next 15 cycles.
(15 Sec with 960° C is Area C)
The Maintenance Manual said:
On airplanes with EGT transitory overtemperature capability or Service Bulletin, no maintenance action is necessary when the maximum EGT is between 930 and 940 degrees C for less than 20 seconds when takeoff or go around power is set. Refer to Boeing Service Letter 737-SL-72-006 for more information.
The Maintenance Manual said:
If the EGT exceedance was 5 seconds or more in Area C you must remove the engine for an overtemperature inspection before the next 15 cycles.
(15 Sec with 960° C is Area C)
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I don't know about your manuals, but ours (747 Classic, CF6 engines) have charts in the non-normal procedures section that give temperature/N1 ranges and time limits, along with the requirements (no action, inspection, shutdown, etc).
In general, a "minor" overtemp is MUCH more serious than a "minor" overspeed...
In general, a "minor" overtemp is MUCH more serious than a "minor" overspeed...
I don't think there is really a wrong answer here - if you feel unhappy about continuing a flight after overtemping an engine, even after advice from the ground, then that is your decision. However, an immediate return to the departure aerodrome might leave you with an overweight landing at e/o speeds in a hot & high scenario: there are definite risks involved with this. Also, the cost of putting a twin with 300 pax on the ground for a day or two plus hotels/allowances/disruption/refunds, etc. might well run to a quarter of a million pounds or more. A bit galling if you can take off again with no more than a tech. log entry.
I'm not suggesting that continuing when you feel it is unsafe is a wise move, just that if professional advice has been given that an engine is OK, a risk assessment has been made. Both engines are still working and if the Company wishes the a/c to carry on, then why not? After all, we plan for an engine failure at any time during the flight as a matter of routine.
I'm not suggesting that continuing when you feel it is unsafe is a wise move, just that if professional advice has been given that an engine is OK, a risk assessment has been made. Both engines are still working and if the Company wishes the a/c to carry on, then why not? After all, we plan for an engine failure at any time during the flight as a matter of routine.
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EGT Exceedence
Gentlemen:
I've now had the opportunity to check the FCOM for the Airbus...last writing, I was without FCOMs.
For our CFM engines, the MAX EGT is 950 degrees. However, in the Abnormal/Emergency procedures section 3.02.70 P3, ENG 1(2) N1/N2/EGT OVERLIMIT, it says that you can go up thru 990 degrees as long as you reduce thrust lever BELOW LIMIT.
"Normal operation may be resumed and maintained until next landing. Report in maintenance log."
However, above 990 degrees, you're directed to shut down the engine.
"If conditions do not permit engine shut-down land ASAP using the minimum thrust required to sustain safe flight."
Now, again, it all depends on how much you went over the 950 limit...and for how long. I remember seeing the chart, but can't tell you specifics. But, in general terms, if you're over by just a few degrees for just a few seconds (e.g. 10 degrees for 15 seconds), it's very likely that no maintenance action is due. (Those figures I pulled out of the air...again, I can't remember specifics of the chart.)
Again, for pilots, any violation of a limitation is cause for concern. For the engineer, it may or may not be a concern.
Airbus recommends, especially in conditions where engines will run hot due to ambient conditions, to either not pressurize for takeoff or use the APU to run the packs. Further, they recommend under such conditions, that you use the maximum FLEX available (if and as conditions warrant). Usually, doing a 'packs-off' takeoff with a lot of FLEX temp added to the equation, you'll not exceed the max temp limitation on takeoff.
It is not "NORMAL" to exceed your max EGT during takeoff, but may be considered "understandable" if the engines are old and haven't been given the T.L.C. they needed from the maintenance department. Again, how little or how much you went over the temp limit and for how long determines what course of action is needed.
PantLoad
I've now had the opportunity to check the FCOM for the Airbus...last writing, I was without FCOMs.
For our CFM engines, the MAX EGT is 950 degrees. However, in the Abnormal/Emergency procedures section 3.02.70 P3, ENG 1(2) N1/N2/EGT OVERLIMIT, it says that you can go up thru 990 degrees as long as you reduce thrust lever BELOW LIMIT.
"Normal operation may be resumed and maintained until next landing. Report in maintenance log."
However, above 990 degrees, you're directed to shut down the engine.
"If conditions do not permit engine shut-down land ASAP using the minimum thrust required to sustain safe flight."
Now, again, it all depends on how much you went over the 950 limit...and for how long. I remember seeing the chart, but can't tell you specifics. But, in general terms, if you're over by just a few degrees for just a few seconds (e.g. 10 degrees for 15 seconds), it's very likely that no maintenance action is due. (Those figures I pulled out of the air...again, I can't remember specifics of the chart.)
Again, for pilots, any violation of a limitation is cause for concern. For the engineer, it may or may not be a concern.
Airbus recommends, especially in conditions where engines will run hot due to ambient conditions, to either not pressurize for takeoff or use the APU to run the packs. Further, they recommend under such conditions, that you use the maximum FLEX available (if and as conditions warrant). Usually, doing a 'packs-off' takeoff with a lot of FLEX temp added to the equation, you'll not exceed the max temp limitation on takeoff.
It is not "NORMAL" to exceed your max EGT during takeoff, but may be considered "understandable" if the engines are old and haven't been given the T.L.C. they needed from the maintenance department. Again, how little or how much you went over the temp limit and for how long determines what course of action is needed.
PantLoad
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Hi Guys, a few comments from a maintenance engineers view. Below is an excerpt from the Fault Isolation Manual for the GE CF6-80C. I also work on Rolls Royce RB211-524D4's-G/H2's, CFM's and Pratt & Whitney JT9's. Each manual is pretty much the same when it comes to EGT exceedance. The level of maintenance/inspection is determined by both the actual temperature recorded and the amount of time spent above the yellow/red line. There is a chart that will determine what "Area" the exceedance falls into based on these factors. These areas are normally A, B and C although some engine types have D as well with A being the least critical and C the most critical. For example, an exceedance of just 5 deg for 300 seconds may put you in the same area as an exceedance of 60 deg for 5 seconds! The chart is fairly exponential with each degree rise in temp substantially reducing the time allowed for operation within this area.
Monitor The Egt Trend And Engine Performance. If The Egt Trend Increases Appear Abnormal,Do The Borescope Inspection (amm 72-00-00) At The First Opportunity.
15 Excursions Into Area A Of High Egt Chart Requires The Removal Of The Engine (amm 71-00-02)For Overtemperature Inspection.
A.
IF THE ENGINE IS OPERATED IN AREA A, DO THE STEPS THAT FOLLOW:
1.IF THE CAUSE OF HIGH EGT IS KNOWN, SUCH AS N1 OVERBOOST, MEC RIGGING, EXCESSIVE AIR BLEED, HIGH ELEVATION AIRPORT, TEMPERATURE INVERSION DURING TAKEOFF, OR HOT DAY (OAT AT OR ABOVE FLAT RATING) CONDITIONS, CORRECT THE CAUSE WHERE POSSIBLE.
2.IF THE CAUSE OF HIGH EGT IS NOT KNOWN, MAKE SURE OF OVERTEMPERATURE AND LOOK AT THE
INDICATION SYSTEM. MONITOR THE EGT TREND AND ENGINE PERFORMANCE FOR INDICATION OF TREND INCREASES. BORESCOPE INSPECT THE ENGINE IF INCREASES APPEAR ABNORMAL.
B.15 EXCURSIONS INTO AREA A AND/OR B REQUIRES ENGINE REMOVAL FOR OVERTEMPERATURE INSPECTION.
NOTE:THE ENGINE MUST BE REMOVED FOR OVERTEMPERATURE INSPECTION IF OPERATED IN AREA C.
Like all limits/exceedances, these charts are on the extremely conservative side. The limits and designs of the aircraft/engines take these exceedances into account. For example on the 747-400 and 767 (and i'm sure many other modern jets) once the throttles are advanced to take-off range and the aircraft speed reaches 80 knots (the A/C thinks it's taking off) any EGT exceedance display is inhibited on EICAS for 5 minutes for 'RED' exceedances and for 10 minutes for "yellow" exceedances. The engines are more than capable of continuing the journey to the next port so long as all indications return to within normal range after thrust reduction. At the 'other end' I'll read the highly detailed Tech Log report that you have written - with your accurate recording of temp's reached and times above limit and then perform the required inspections, borescopes and/or change the engine if need be. Oh, yeah - How are you going to do this if EICAS hides the exceedance during Take-off?? Not to worry, EICAS does all this for you giving a nice plot on the maintenance screen of all the temp and time info. You'll know of the exceedance as it will paint the EGT indication box yellow or red for you on upper EICAS - even when the temp has returned to normal. If you really have 'cooked' the engine the turbine blades will give up, become soft due to excess heat, stretch like plasticine, rub against the turbine case and "Bang" you're now dealing with an engine failure as opposed to an exceedance and I'm sure your hand is then forced!
Whilst I would never be so bold as to offer advice on what pilots should or shouldn't do during a flight it would be my opinion that an immediate return would not be required just on the basis of the needle going past the limit line. Just write it up in the Tech Log and/or call your maintenance base for advice. Of course, once I've done your pushback and got your engines going, the moment I unplug my headset and give you a wave - you're in command. If you choose to return for an EGT exceedance that of course is your prerogative - I just wouldn't want to be in your shoes when you're called to The Chief Pilots office for a "Please Explain" We all know the potential costs of an Air Turn Back and I'm guessing you guys have to be able to back-up your "Command' decisions.
This post obviously tilted towards the 747 / 767 so sorry for the long ramble for you pilots who fly other types.
Monitor The Egt Trend And Engine Performance. If The Egt Trend Increases Appear Abnormal,Do The Borescope Inspection (amm 72-00-00) At The First Opportunity.
15 Excursions Into Area A Of High Egt Chart Requires The Removal Of The Engine (amm 71-00-02)For Overtemperature Inspection.
A.
IF THE ENGINE IS OPERATED IN AREA A, DO THE STEPS THAT FOLLOW:
1.IF THE CAUSE OF HIGH EGT IS KNOWN, SUCH AS N1 OVERBOOST, MEC RIGGING, EXCESSIVE AIR BLEED, HIGH ELEVATION AIRPORT, TEMPERATURE INVERSION DURING TAKEOFF, OR HOT DAY (OAT AT OR ABOVE FLAT RATING) CONDITIONS, CORRECT THE CAUSE WHERE POSSIBLE.
2.IF THE CAUSE OF HIGH EGT IS NOT KNOWN, MAKE SURE OF OVERTEMPERATURE AND LOOK AT THE
INDICATION SYSTEM. MONITOR THE EGT TREND AND ENGINE PERFORMANCE FOR INDICATION OF TREND INCREASES. BORESCOPE INSPECT THE ENGINE IF INCREASES APPEAR ABNORMAL.
B.15 EXCURSIONS INTO AREA A AND/OR B REQUIRES ENGINE REMOVAL FOR OVERTEMPERATURE INSPECTION.
NOTE:THE ENGINE MUST BE REMOVED FOR OVERTEMPERATURE INSPECTION IF OPERATED IN AREA C.
Like all limits/exceedances, these charts are on the extremely conservative side. The limits and designs of the aircraft/engines take these exceedances into account. For example on the 747-400 and 767 (and i'm sure many other modern jets) once the throttles are advanced to take-off range and the aircraft speed reaches 80 knots (the A/C thinks it's taking off) any EGT exceedance display is inhibited on EICAS for 5 minutes for 'RED' exceedances and for 10 minutes for "yellow" exceedances. The engines are more than capable of continuing the journey to the next port so long as all indications return to within normal range after thrust reduction. At the 'other end' I'll read the highly detailed Tech Log report that you have written - with your accurate recording of temp's reached and times above limit and then perform the required inspections, borescopes and/or change the engine if need be. Oh, yeah - How are you going to do this if EICAS hides the exceedance during Take-off?? Not to worry, EICAS does all this for you giving a nice plot on the maintenance screen of all the temp and time info. You'll know of the exceedance as it will paint the EGT indication box yellow or red for you on upper EICAS - even when the temp has returned to normal. If you really have 'cooked' the engine the turbine blades will give up, become soft due to excess heat, stretch like plasticine, rub against the turbine case and "Bang" you're now dealing with an engine failure as opposed to an exceedance and I'm sure your hand is then forced!
Whilst I would never be so bold as to offer advice on what pilots should or shouldn't do during a flight it would be my opinion that an immediate return would not be required just on the basis of the needle going past the limit line. Just write it up in the Tech Log and/or call your maintenance base for advice. Of course, once I've done your pushback and got your engines going, the moment I unplug my headset and give you a wave - you're in command. If you choose to return for an EGT exceedance that of course is your prerogative - I just wouldn't want to be in your shoes when you're called to The Chief Pilots office for a "Please Explain" We all know the potential costs of an Air Turn Back and I'm guessing you guys have to be able to back-up your "Command' decisions.
This post obviously tilted towards the 747 / 767 so sorry for the long ramble for you pilots who fly other types.
Last edited by Spanner Turner; 1st Sep 2006 at 06:40. Reason: Paragraph spacing
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Thanks Gents for your replies.
Just to confirm, the scenario, which did not happen to me, calls for the EGT overlimit on both engines simultaneously.
Besides all the various considerations, like doing a no engine bleed takeoff when it's necessary to use full thrust under hot-heavy etc, or monitoring with more attention the parameters at takeoff, the fact remains: between V1 and 400ft, what happens happens, and the Commander is left, in our scenario, with absolutely no information available: no exceedance tables, no satellite, no phone, nothing!
In this case, he can't tell if the exceedance is acceptable or not, unless...
Unless he already has experience / knowledge of this matter.
Good to get IFixPlanes's data.
*****************************************************
And now that I've found what I was looking for - the whole maintenance manual, buried deeply in my pc, siamo a cavallo! (in italian this means we are ON the horse - we're saved)...
Actually, I can confirm the scenario is NOT that critical, if you go through the various areas and related instructions, you'll see they are quite permissive, if compared to what one might think instinctively.
For example, in area B, that means up to 950° for up to one full minute (!), one of the statements is:
Just to confirm, the scenario, which did not happen to me, calls for the EGT overlimit on both engines simultaneously.
Besides all the various considerations, like doing a no engine bleed takeoff when it's necessary to use full thrust under hot-heavy etc, or monitoring with more attention the parameters at takeoff, the fact remains: between V1 and 400ft, what happens happens, and the Commander is left, in our scenario, with absolutely no information available: no exceedance tables, no satellite, no phone, nothing!
In this case, he can't tell if the exceedance is acceptable or not, unless...
Unless he already has experience / knowledge of this matter.
Good to get IFixPlanes's data.
*****************************************************
And now that I've found what I was looking for - the whole maintenance manual, buried deeply in my pc, siamo a cavallo! (in italian this means we are ON the horse - we're saved)...
Actually, I can confirm the scenario is NOT that critical, if you go through the various areas and related instructions, you'll see they are quite permissive, if compared to what one might think instinctively.
For example, in area B, that means up to 950° for up to one full minute (!), one of the statements is:
A maximum of 10 exceedances in Areas A and B combined are
permitted before the engine must be removed for an
overtemperature inspection.
permitted before the engine must be removed for an
overtemperature inspection.
I think I'll definitely print the whole stuff and put it in my crew bag!
Thanks a lot everyone for your precious input.
Paolo
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I know some operators use a minimum of 400 ft above ground level as the first "action" altitude but surely this is an advisory altitude and like most things in aviation, not set in stone. The usual caveat is to ensure the aircraft is under control and then take a specific action because somewhere along the line 400 ft is where the altitude is considered "safe". But the only reason 400 ft is the generally accepted "safe" altitude is that it is the minimum altitude at which the second segment is commenced. It does not imply that anything below 400 ft is dangerous.
So if the EGT is giving a serious problem after rotation and you have not lost an engine and assuming the aircraft is under control (which it would be seeing as the engines are working), then I see no problem in easing back the thrust lever of the offending EGT to keep it within limits.
I mean, for goodness sake are you really going to happily watch an engine EGT going over red line after lift off and count the seconds until you get to the magic certification second segment figure of 400 ft agl and then and only then start to pull back the throttle and by delaying so long bugger the engine and cost your company Lots of $$$$$$ ?
So if the EGT is giving a serious problem after rotation and you have not lost an engine and assuming the aircraft is under control (which it would be seeing as the engines are working), then I see no problem in easing back the thrust lever of the offending EGT to keep it within limits.
I mean, for goodness sake are you really going to happily watch an engine EGT going over red line after lift off and count the seconds until you get to the magic certification second segment figure of 400 ft agl and then and only then start to pull back the throttle and by delaying so long bugger the engine and cost your company Lots of $$$$$$ ?
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I know some operators use a minimum of 400 ft above ground level as the first "action" altitude but surely this is an advisory altitude and like most things in aviation, not set in stone. The usual caveat is to ensure the aircraft is under control and then take a specific action because somewhere along the line 400 ft is where the altitude is considered "safe". But the only reason 400 ft is the generally accepted "safe" altitude is that it is the minimum altitude at which the second segment is commenced. It does not imply that anything below 400 ft is dangerous.
So if the EGT is giving a serious problem after rotation and you have not lost an engine and assuming the aircraft is under control (which it would be seeing as the engines are working), then I see no problem in easing back the thrust lever of the offending EGT to keep it within limits.
I mean, for goodness sake are you really going to happily watch an engine EGT going over red line after lift off and count the seconds until you get to the magic certification second segment figure of 400 ft agl and then and only then start to pull back the throttle and by delaying so long bugger the engine and cost your company Lots of $$$$$$ ?
So if the EGT is giving a serious problem after rotation and you have not lost an engine and assuming the aircraft is under control (which it would be seeing as the engines are working), then I see no problem in easing back the thrust lever of the offending EGT to keep it within limits.
I mean, for goodness sake are you really going to happily watch an engine EGT going over red line after lift off and count the seconds until you get to the magic certification second segment figure of 400 ft agl and then and only then start to pull back the throttle and by delaying so long bugger the engine and cost your company Lots of $$$$$$ ?
While there was some talk about the Pinnacle CRJ suffering a "core lock" below the certified safe altitude, there have also been suggestions that the pilots overheated the engine by trying to climb fast in thin air. Causing both engines to fail in quick succession... and there was no way those engines could be restarted. The pilots did not succeed in making a deadstick landing.
400 ft agl is probably too low for a safe deadstick landing...
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As a general turbine operational technique (not specific to any engine):
A well warmed-up engine will probably peak at lower EGT on TO than a colder one. So - doing a part-power (80% N1 or so) runup for maybe a minute will likely be of benefit in keeping EGT down. If it's a cold engine (shutdown for 6 hours or more), another minute might help.
Of course, the usual precautions about FOD, erosive ingestion, jet blast etc. still apply, and there's the added fuel to consider. But if your back is to the wall...
A well warmed-up engine will probably peak at lower EGT on TO than a colder one. So - doing a part-power (80% N1 or so) runup for maybe a minute will likely be of benefit in keeping EGT down. If it's a cold engine (shutdown for 6 hours or more), another minute might help.
Of course, the usual precautions about FOD, erosive ingestion, jet blast etc. still apply, and there's the added fuel to consider. But if your back is to the wall...
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It's been discussed before on Pprune - maybe a year ago.
Essentially it's this: Rotors are massive forgings, and heat up & expand slowly. Casings are light by comparison, and heat up & expand quickly.
During takeoff, the differential in thermal growth produces a temporary increase in rotor-to-stator clearances, which are leakage paths for the airflow in the engine. More leakage => lower engine efficiency => higher EGT.
The static runup tends to help get the rotor warmed up, and clearances close to normal, before the takeoff begins.
That said, the most modern engines often have some active clearance control scheme to help mitigate the above processes; but the warmup technique will still probably help some.
Essentially it's this: Rotors are massive forgings, and heat up & expand slowly. Casings are light by comparison, and heat up & expand quickly.
During takeoff, the differential in thermal growth produces a temporary increase in rotor-to-stator clearances, which are leakage paths for the airflow in the engine. More leakage => lower engine efficiency => higher EGT.
The static runup tends to help get the rotor warmed up, and clearances close to normal, before the takeoff begins.
That said, the most modern engines often have some active clearance control scheme to help mitigate the above processes; but the warmup technique will still probably help some.