Reverse thrust in flight
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Reverse thrust in flight
I wa reading the background to the LAUDA B767 accident and I understand that when investigators tried ehe scenarion in the sim ,they discovered after some trials, that an aircraft was theoretically recoverable but in a very small time window ( 4-6 secs?) provided that the pilots were aware of that which needed to be effected. Can any professional confirm whether pilots are required to practice such a scenario in the sim or is it that the subsequent inhibit technology now guarantees (?) that such a scenario is not posible thereby rendering such scenario not requisite training . I think it ia analogous to the rudder hard -over on B737s raising the same questions- grateful for any advice from the Pros. Thanks
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reverse thrust
As far as I understand,the only aircraft to successfully apply reverse thrust in flight was Concorde,and that was used to slow the aircraft back down to subsonic speeds.
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Yes it is practised in the sim. The 'crippler' is an aircraft with 'bucket' reversers, and you need to be quick to identify and shut down particularly on take-off.
Mistrust in Management
As far as I understand,the only aircraft to successfully apply reverse thrust in flight was Concorde,and that was used to slow the aircraft back down to subsonic speeds.
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Exeng
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that was used to slow the aircraft back down to subsonic speeds.
- deploying a reverser or two at Mach 2 - wow! Cojones of steel, eh. (the late, lovely Barbara excluded, of course)
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Well, barely inflight but on the 737 you can open reverse below 10ft radar altitude. It is not recommended of course, but possible.
Apart from a demonstration during initial type rating we never trained an open reverser inflight, reverser unlock light yes, but not actually opened.
Apart from a demonstration during initial type rating we never trained an open reverser inflight, reverser unlock light yes, but not actually opened.
On the F70/100, it was occasionally trained in the simulator.
The engineers at Fokker were smart guys - they installed a cable between the reverser buckets and the fuel control unit that forces the thrust levers to idle (and slammed the lever to that position quite forcefully) whenever the buckets were opened. Any desired reverse thrust increase had to be commanded via the TR levers only.
It certainly was a bumpy experience until the engine was shut down, but I was under the impression that it was flyable. However, I have no desire to try this in a real plane.
The engineers at Fokker were smart guys - they installed a cable between the reverser buckets and the fuel control unit that forces the thrust levers to idle (and slammed the lever to that position quite forcefully) whenever the buckets were opened. Any desired reverse thrust increase had to be commanded via the TR levers only.
It certainly was a bumpy experience until the engine was shut down, but I was under the impression that it was flyable. However, I have no desire to try this in a real plane.
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dixi188:
DC-8 with stove pipe engines was allowed to reverse inboards in flight. Not allowed on the CFM56 powered ones though.
DC-8 with stove pipe engines was allowed to reverse inboards in flight. Not allowed on the CFM56 powered ones though.
The Emergency Stow Pump still exists, as it did prior to the CFM engine mod.
The spoiler system is only for roll control assist with the gear down and for spoiler deployment after touchdown. No speedbrake duties.
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Concorde didn't decellerate with reverse, it was an option (with various do's/don'ts/be carefuls) to increase rate of descent..
Have seen an uncommanded thrust reverser deployment on the 757 just after take off (in the simulator...), and neither training captain could recover it!!
Have seen an uncommanded thrust reverser deployment on the 757 just after take off (in the simulator...), and neither training captain could recover it!!
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Agreed the CFM powered DC8s were indeed authorised for in-flight reverser deployment, experienced it many times working as a flight tech on board Southern air transports DC8s.
I stand corrected re. the CFM powered DC-8.
I was jumpseating on a UPS DC-8-73 some years ago when the capt. pulled the inboard reverse levers in descent. The Flight Engineer slapped his hand down and said "No you don't, not with these engines"
Maybe it was a UPS thing or just bad CRM.
I was jumpseating on a UPS DC-8-73 some years ago when the capt. pulled the inboard reverse levers in descent. The Flight Engineer slapped his hand down and said "No you don't, not with these engines"
Maybe it was a UPS thing or just bad CRM.
OK, I've waited long enough, an ex Trident pilot has to give an input at some time in this thread......
The Trident might not have leapt skywards, as is the current fashion, but it was certainly a high speed cruiser, Mno 0.885 for the Trident 1A, if I remember correctly. However, the use of in flight reverse made it capable of rates of descent similar to that of a falling manhole cover. With the speed pegged at cruise Mach, transitting to 380 kts Vmo, full speed brake, plus about 90% reverse thrust on the pod engines it was capable of rates of descent in excess of 18,000 ft min. ATC were aware of this re-entry capability and often made good use of it.
Furthermore, to improve stopping capability on short runways, full reverse could be selected in the landing flare so that max reverse thrust was being achieved at touchdown. There was a natural pitch up with this technique which usually helped smooth the touchdown, but the slightest misjudgment could result in in very firm touchdown.
I would be interested to know if other types with in-flight reverse were allowed to use more than reverse idle power.
The Trident might not have leapt skywards, as is the current fashion, but it was certainly a high speed cruiser, Mno 0.885 for the Trident 1A, if I remember correctly. However, the use of in flight reverse made it capable of rates of descent similar to that of a falling manhole cover. With the speed pegged at cruise Mach, transitting to 380 kts Vmo, full speed brake, plus about 90% reverse thrust on the pod engines it was capable of rates of descent in excess of 18,000 ft min. ATC were aware of this re-entry capability and often made good use of it.
Furthermore, to improve stopping capability on short runways, full reverse could be selected in the landing flare so that max reverse thrust was being achieved at touchdown. There was a natural pitch up with this technique which usually helped smooth the touchdown, but the slightest misjudgment could result in in very firm touchdown.
I would be interested to know if other types with in-flight reverse were allowed to use more than reverse idle power.
Bingofuel:
I detect a note of scepticism methinks.
18,000fpm is a genuine figure and could be exceeded. It was achievable at higher levels but it was only too easy to 'catch the cabin' if those descent rates were sustained to low altitude. There was a 'bird speed' restriction at lower altitudes and the manoeuvre required to back the speed off by 70kts or so usually gave the cabin time to get back on schedule. It did need careful watching, but by a third pilot on the systems panel, not a F/E.
By the way, the Trident model I describe was a 1C, drooped leading edge and 38 degree sweepback.
I detect a note of scepticism methinks.
18,000fpm is a genuine figure and could be exceeded. It was achievable at higher levels but it was only too easy to 'catch the cabin' if those descent rates were sustained to low altitude. There was a 'bird speed' restriction at lower altitudes and the manoeuvre required to back the speed off by 70kts or so usually gave the cabin time to get back on schedule. It did need careful watching, but by a third pilot on the systems panel, not a F/E.
By the way, the Trident model I describe was a 1C, drooped leading edge and 38 degree sweepback.