Clmb performance following an engine failure during or after acceleration
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Clmb performance following an engine failure during or after acceleration
I know that a airliner is meant to achieve at least a 2.5% climb gradient until the aircraft has accelerated but what is the case for instance if the engine failure occurs during acceleration?
Does anybody have an up to date version of what used to be known as perf A?
Does anybody have an up to date version of what used to be known as perf A?
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Ever heard of something called V2 plus 10? Hold that, clean the flaps up, and accelerate after clean...
As for climb gradient...V2 plus 10...hold that and live with what you get...
As for climb gradient...V2 plus 10...hold that and live with what you get...
Think of it this way - if it can meet the 2nd segment climb with one engine failed, by the time you get to the acceleration (3rd segment) with all engines, you already have money in the bank. Chances are you would be higher and faster than the minimum called for by certification, as that assumed the failure way back at V1. I can't think of any aircraft type that would fail to meet the requirements at this stage of the departure, as the RTOW analysis considers the most critical element of the flight path, both all-engines and OEI.
Just complete the clean-up, go to MCT and climb away on the OEI schedule.
Just complete the clean-up, go to MCT and climb away on the OEI schedule.
Last edited by Mach E Avelli; 26th May 2013 at 05:51.
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Acceleration
Hi
If an engine failure occurs during the acceleration segment it will apply to both the third and fourth segments, depending at which point in time the failure will take place.
Third Segment: This segment extends from the end of the second segment upon reaching the acceleration altitude not less than 400ft agl, to the completion of flap retraction and acceleration to Vfto. Meeting the 3rd segment requirements means that you can start at V2 and flaps takeoff, and accelerate to Vfto retracting the flaps during the appropriate part of the acceleration, all without any loss of altitude. Airspeed Accelerating to Vfto,
Critical engine Failed, Thrust Takeoff or APR, Flaps Retracting to 0 deg, Minimum Climb Gradient 0.0%
Fourth Segment: This segment begins at the end of the third segment (flaps retracted), and ends at a height of 1500 feet AGL. This segment completes the takeoff path. Airspeed Vfto, critical engine Failed, Thrust Max Continuous, Flaps Retracted, Minimum Climb Gradient 1.2%.
the aircraft performance will be the one shown on the vfto chart or the chart that applies to the speed for final takeoff with the flaps retracted according to the schedule specific to your aircraft (vfto-5 in the case of the cl605), the gear up and the climb thrust, found in the afm in the climb gradient section.
Hope it helps
Baobab
If an engine failure occurs during the acceleration segment it will apply to both the third and fourth segments, depending at which point in time the failure will take place.
Third Segment: This segment extends from the end of the second segment upon reaching the acceleration altitude not less than 400ft agl, to the completion of flap retraction and acceleration to Vfto. Meeting the 3rd segment requirements means that you can start at V2 and flaps takeoff, and accelerate to Vfto retracting the flaps during the appropriate part of the acceleration, all without any loss of altitude. Airspeed Accelerating to Vfto,
Critical engine Failed, Thrust Takeoff or APR, Flaps Retracting to 0 deg, Minimum Climb Gradient 0.0%
Fourth Segment: This segment begins at the end of the third segment (flaps retracted), and ends at a height of 1500 feet AGL. This segment completes the takeoff path. Airspeed Vfto, critical engine Failed, Thrust Max Continuous, Flaps Retracted, Minimum Climb Gradient 1.2%.
the aircraft performance will be the one shown on the vfto chart or the chart that applies to the speed for final takeoff with the flaps retracted according to the schedule specific to your aircraft (vfto-5 in the case of the cl605), the gear up and the climb thrust, found in the afm in the climb gradient section.
Hope it helps
Baobab
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Mach E Avelli has it right. If both engines have been operating up to the acceleration point then the aircraft will be miles above any required engine failure on take off profile.
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Matey:
Yes, but..... 
At a mountain airport there may still very well be a OEI en route climb issue.
Mach E Avelli has it right. If both engines have been operating up to the acceleration point then the aircraft will be miles above any required engine failure on take off profile.
At a mountain airport there may still very well be a OEI en route climb issue.
Last edited by aterpster; 26th May 2013 at 22:20.
If there is a further limitation, or one more critical than initial OEI path, the RTOW analysis should have considered this.
Whatever it may be, the optimum performance to clear terrain (assuming no close-in turns are required) will be at MCT, clean, at Vfto/Ver. So, once the acceleration altitude has been reached, that is the aim of the game - get it cleaned up, select MCT before the engine take-off limitation is busted and continue to climb and turn etc as necessary.
If close-in turns are required, the special departure or emergency procedure will detail these. If turns must be commenced below acceleration altitude, the usual practice is not less than V2 to V2 + 10, 15 degrees bank angle and complete the turn - even if in so doing the aircraft achieves something greater than the acceleration altitude. The acceleration and clean up is usually done wings-level, i.e. not while in the emergency turn.
Sometimes I get asked "what if the emergency turn direction is one way and the SID or radar heading is in another direction?" This is where common-sense needs to come into play. If below acceleration altitude at the time of the failure, go for the emergency turn direction. If acceleration altitude has been achieved, complete the clean up, declare an emergency and turn away from the limiting terrain if the SID is taking you where you don't want to go, otherwise fly the SID. Critical SIDs will publish a minimum climb gradient, so you should have already considered that anyway and have a quick way of computing it in your brain by looking at your groundspeed and IVSI to know if you can make it. There are too many airports, too many variables to lay down hard and fast rules, but that one works for me.
Whatever it may be, the optimum performance to clear terrain (assuming no close-in turns are required) will be at MCT, clean, at Vfto/Ver. So, once the acceleration altitude has been reached, that is the aim of the game - get it cleaned up, select MCT before the engine take-off limitation is busted and continue to climb and turn etc as necessary.
If close-in turns are required, the special departure or emergency procedure will detail these. If turns must be commenced below acceleration altitude, the usual practice is not less than V2 to V2 + 10, 15 degrees bank angle and complete the turn - even if in so doing the aircraft achieves something greater than the acceleration altitude. The acceleration and clean up is usually done wings-level, i.e. not while in the emergency turn.
Sometimes I get asked "what if the emergency turn direction is one way and the SID or radar heading is in another direction?" This is where common-sense needs to come into play. If below acceleration altitude at the time of the failure, go for the emergency turn direction. If acceleration altitude has been achieved, complete the clean up, declare an emergency and turn away from the limiting terrain if the SID is taking you where you don't want to go, otherwise fly the SID. Critical SIDs will publish a minimum climb gradient, so you should have already considered that anyway and have a quick way of computing it in your brain by looking at your groundspeed and IVSI to know if you can make it. There are too many airports, too many variables to lay down hard and fast rules, but that one works for me.
Last edited by Mach E Avelli; 27th May 2013 at 05:22.
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There are often 'engine-out' performance considerations past the end of the calculated performance altitude (often only 1500' AGL), an example being taking off from Bergamo and heading north. An engine failure later in the climb requires 'action' to avoid flying into those big lumps by ensuring MSA is achieved (if not returning south). These issues are rarely 'calculated' into departure tables or included in airline airfield 'briefs', should be 'common sense' ('airmanship? - acknowledgements to 'Ag Bis') and it is a good idea to bear them in mind when accepting 'direct' short cuts on departures unless visual all the way.
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and it is a good idea to bear them in mind when accepting 'direct' short cuts on departures unless visual all the way.
-saggio, prudente
Last edited by Natstrackalpha; 27th May 2013 at 23:55.
