Engine Auto-Deceleration in Reverse Based on Groundspeed
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Joined: Nov 2019
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From: unknown
Engine Auto-Deceleration in Reverse Based on Groundspeed
Looks like the Citation Longitude has a FADEC controlled feature where the engines automatically decelerate to a 'safe level' regardless of thrust Lever position as the aircraft slows. Has anybody seen this feature on any other aircraft and is there a name for this feature.
Or another name for Approach Idle?
Joined: May 2005
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From: France
The Global 5000 has a similar feature. From the FCOM:
”The EEC modulates engine power with maximum reverse thrust selected. A maximum of 70% N1 is available above 65 knots. Engine power is linearly reduced to a maximum of 50% N1 at 50 knots and below.”
It doesn’t say whether it’s ground speed or airspeed. Probably ground speed. There is no name given for this feature.
”The EEC modulates engine power with maximum reverse thrust selected. A maximum of 70% N1 is available above 65 knots. Engine power is linearly reduced to a maximum of 50% N1 at 50 knots and below.”
It doesn’t say whether it’s ground speed or airspeed. Probably ground speed. There is no name given for this feature.
Only half a speed-brake
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From: Commuting not home
aterpster
Given the conditions then, would the approach and landing be legal under today's rules, under TALPA-ARC and OLD landing performance concepts? I.e. did we grow wiser about what shall not even be attempted - at least on paper? An honest question. Hoping for a positive answer while a negative one will have more educative value. Thanks.
Given the conditions then, would the approach and landing be legal under today's rules, under TALPA-ARC and OLD landing performance concepts? I.e. did we grow wiser about what shall not even be attempted - at least on paper? An honest question. Hoping for a positive answer while a negative one will have more educative value. Thanks.
Joined: Apr 2004
Aviation Qualifications: LAME
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From: Dorset UK
FlightDetent
Some years ago at East Midlands the snow had been cleared and Braking action reported as good. We were the first to land and had to go to the end to vacate. All well until the last 1500 ft which was sheet ice and all 8 "R" lights on the anti skid panel were going on-off-on-off. We were doing about 40 knots and the reversers were all that saved us from going off the end.
Some years ago at East Midlands the snow had been cleared and Braking action reported as good. We were the first to land and had to go to the end to vacate. All well until the last 1500 ft which was sheet ice and all 8 "R" lights on the anti skid panel were going on-off-on-off. We were doing about 40 knots and the reversers were all that saved us from going off the end.
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From: The Ghetto
Joined: Jan 2009
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From: Cab of a Freight Train
Originally Posted by Flying Stone
Is it just me who thinks that engine life should come second to safety when it comes to stopping on a contaminated runway, where full reverse thrust could be required even at low speeds?
To my mind, if you need to bend, or break, parts of the airplane to prevent a greater incident, you should be able to. If that means full reverse down to 0kts so be it. Too many of my toys at work (another industry, not flying anymore) have these self-protection features and they work well 99.9% of the time. The other .1% they increase the hazards or introduce additional safety risks.
Joined: Mar 2006
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From: USA
Hopefully if the plane goes off a cliff at the end of the runway, the engine won’t be damaged too badly...
Any engineering types tdracer care to comment on what failure modes the manufacturer would have considered before implementing this feature?
Any engineering types tdracer care to comment on what failure modes the manufacturer would have considered before implementing this feature?
Joined: Mar 2006
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From: USA
I understand why they'd want it, my question was about what things they'd have considered as possible failure points before designing the plane this way. Seems like a solution to a problem that doesn't exist. If anything, people come out of reverse prematurely, not too late.
As has been mentioned before, it seems any point of failure in this system will potentially cost way more than a pair of engines.
As has been mentioned before, it seems any point of failure in this system will potentially cost way more than a pair of engines.
Joined: Jul 2008
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From: The Ghetto
1. Trying to prevent fod ingestion
2. engine instability due possible reingestion of burnt exhaust gases(reverser looks to be both core and fan reverse)
that’s my best guess. Id assume driver couldn’t give a rodents bum about either if he is running out of pavement.
not sure why they did it on the 220 as it’s a fan reverser. Maybe it will get binned when they figure how to install ROW/ROPS.
2. engine instability due possible reingestion of burnt exhaust gases(reverser looks to be both core and fan reverse)
that’s my best guess. Id assume driver couldn’t give a rodents bum about either if he is running out of pavement.
not sure why they did it on the 220 as it’s a fan reverser. Maybe it will get binned when they figure how to install ROW/ROPS.
Joined: Dec 2003
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From: Tring, UK
Maybe one answer is to use a bigger safety factor when landing on contaminated runways in this type? It seems strange that there is no mention of an override: at least with most implementations of thrust levers, if you push them as far forward as they go, you get the most the engine can produce, even if you’re using reduced thrust at the time. If you yanked the reversers back all the way, you’d hope the system would recognise that was what you wanted, irrespective of everything else. Like “ground contact imminent” when airborne.
I too have had a pucker-factor 50 moment landing on a slushy runway and having to rely on full reverse to bring us to a halt ~50m short of the end, due to the braking action being very different from that reported. We might have made it going to idle but it wasn’t research I wished to conduct at the time...
I too have had a pucker-factor 50 moment landing on a slushy runway and having to rely on full reverse to bring us to a halt ~50m short of the end, due to the braking action being very different from that reported. We might have made it going to idle but it wasn’t research I wished to conduct at the time...