DocLightning From United States of America, joined Nov 2005, 16812 posts, RR: 57 Posted (4 years 10 months 2 weeks 4 days 7 hours ago) and read 7698 times:
Jetstar From United States of America, joined May 2003, 1523 posts, RR: 10 Reply 1, posted (4 years 10 months 2 weeks 3 days 15 hours ago) and read 7663 times:
It looks like they just deployed the thrust reversers, probably landing on a short runway to get them extended and ready for thrust reverse application as soon as they touch down. Normally as soon as you pull up on the thrust reverser levers, the reversers will extend, but it takes pulling up on the reverser levers to increase engine thrust to make the reversers effective.
On the Lockheed JetStar we occasionally did this landing on a short runway, there was no weight on wheels switch or auto reverse thrust, as long as the power levers were back to idle we could deploy the reversers, so as soon as we pulled the throttle levers back to idle just before touch down we extended the reverser buckets and were ready to apply reverse thrust.
Turbine jet engines can have a few second lag from the time of reverser deployment to full reverse thrust, so by getting the reverser buckets out early and even pulling up on the thrust reverser levers the engines would start spooling up and by the time the wheels touched down, enough reverse thrust would be available to start slowing the airplane down as max thrust reverse was applied
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 2, posted (4 years 10 months 2 weeks 3 days 15 hours ago) and read 7661 times:
Quoting Jetstar (Reply 1): Turbine jet engines can have a few second lag from the time of reverser deployment to full reverse thrust, so by getting the reverser buckets out early and even pulling up on the thrust reverser levers the engines would start spooling up and by the time the wheels touched down, enough reverse thrust would be available to start slowing the airplane down as max thrust reverse was applied
I wonder if such a procedure is officially approved and/or recommended in any flight manuals...
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 4, posted (4 years 10 months 2 weeks 3 days 12 hours ago) and read 7590 times:
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Quoting Starlionblue (Reply 3): The question, as 2H4 says, is if this is approved in the manual.
Actually, this thread could become very interesting......does anyone here know of a procedure that, while approved in the flight manual, is in your opinion unsafe or unwise?
The only I can think of off the top of my head are rather extreme flap settings in some older 172s and 182s that make landings a bit dodgy when operating at light weights. I think the combination of full flaps and light weights have set a lot of pilots up for nosewheel-first landings over the years.
SashA From Russia, joined May 1999, 858 posts, RR: 0 Reply 5, posted (4 years 10 months 2 weeks 3 days 12 hours ago) and read 7582 times:
Seems to be a common thing at least in Russia. Yak 40, Tu 154 and IL62 deploy thrust reverse whenever landing in challending weather conditions to avoid risk of runway overrun (slippery surface etc).
Viscount724 From Switzerland, joined Oct 2006, 21464 posts, RR: 24 Reply 6, posted (4 years 10 months 2 weeks 3 days 12 hours ago) and read 7575 times:
The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that.
Jetstar From United States of America, joined May 2003, 1523 posts, RR: 10 Reply 7, posted (4 years 10 months 2 weeks 3 days 10 hours ago) and read 7524 times:
Quoting 2H4 (Reply 2): I wonder if such a procedure is officially approved and/or recommended in any flight manuals...
If I remember correctly, deploying the thrust reversers before wheels touching down was not in the JetStar flight manual, but also there was no prohibition in the manual about not doing it, so I guess it’s a gray area. Also I am only talking about the legacy P&W powered JetStar, not the 731 varsion.
WILCO737 From Greenland, joined Jun 2004, 8473 posts, RR: 78 Reply 8, posted (4 years 10 months 2 weeks 3 days 9 hours ago) and read 7489 times:
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Some aircrafts are certified to use the thrust reverser before touchdown. On most aircraft the thrust reverser won't be operable until the air/ ground sensor on the wheels senses ground. Like on the MD11F. Only when the main wheels are on the ground you will be able to activate the thrust reverser. And thrust reverser number two will only be available for full thust reverse once the nose gear is on the ground (MD11F). Sometimes you see eng #1 and #3 on full reverse and #2 is still on its way to full reverse
Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66 Reply 9, posted (4 years 10 months 2 weeks 3 days 4 hours ago) and read 7405 times:
Quoting Viscount724 (Reply 6): The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that
Yes but not on final approach.
Quoting WILCO737 (Reply 8): Like on the MD11F. Only when the main wheels are on the ground you will be able to activate the thrust reverser. And thrust reverser number two will only be available for full thust reverse once the nose gear is on the ground (MD11F). Sometimes you see eng #1 and #3 on full reverse and #2 is still on its way to full reverse
I'm guessing that if #2 deploys before nose wheel touch down there will be a rotating moment in the wrong direction, keeping the nose wheel up longer than wanted.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
WILCO737 From Greenland, joined Jun 2004, 8473 posts, RR: 78 Reply 10, posted (4 years 10 months 2 weeks 3 days 4 hours ago) and read 7402 times:
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Quoting Starlionblue (Reply 9): I'm guessing that if #2 deploys before nose wheel touch down there will be a rotating moment in the wrong direction, keeping the nose wheel up longer than wanted.
When the main wheels touchdown, all three thrust reverser can be engages in idle. You can move the thrust lever to full reverse thrust, but the FADEC will keep eng #2 at idle reverse until the nose gear is on the ground. then it spools up to full reverse thrust.
And about the moment you are right. To avoid a pitch up moment during or right after touchdown, it is designed like this. Same with the spoilers. with main gear touchdown they come out 2/3rd and with nose gear touchdown they move to full extend...
XT6Wagon From United States of America, joined Feb 2007, 3130 posts, RR: 4 Reply 11, posted (4 years 10 months 2 weeks 3 days 3 hours ago) and read 7397 times:
The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.
David L From United Kingdom, joined May 1999, 9213 posts, RR: 42 Reply 12, posted (4 years 10 months 2 weeks 2 days 23 hours ago) and read 7353 times:
Quoting Viscount724 (Reply 6): The DC-8 is also certified for inflight use of thrust reversers.
As was the HS Trident. It could achieve a decsent rate of ~10,000 fps if necessary, though the FE apparently had to work very hard to regulate the cabin pressure. From memory, I'm pretty sure it was approved on Concorde, too.
CosmicCruiser From United States of America, joined Feb 2005, 2211 posts, RR: 16 Reply 13, posted (4 years 10 months 2 weeks 2 days 23 hours ago) and read 7339 times:
Quoting Jetstar (Reply 7): If I remember correctly, deploying the thrust reversers before wheels touching down was not in the JetStar flight manual, but also there was no prohibition in the manual about not doing it
Quoting Jetstar (Reply 7): Also I am only talking about the legacy P&W powered JetStar, not the 731 varsion.
Yea, I flew both versions of the Jetstar for about 3 years and we never deployed the reversers prior to tochdown and I don't remember it ever being discussed in grd. school at Marietta nor Flight Safety but then I speaking of 35 yrs ago!!
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 14, posted (4 years 10 months 2 weeks 2 days 22 hours ago) and read 7322 times:
Quoting XT6Wagon (Reply 11): The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.
Are you saying B734.
Why not Air-Grd sense.
regds
MEL
DocLightning From United States of America, joined Nov 2005, 16812 posts, RR: 57 Reply 15, posted (4 years 10 months 2 weeks 2 days 18 hours ago) and read 7238 times:
Quoting Jetstar (Reply 1): Normally as soon as you pull up on the thrust reverser levers, the reversers will extend, but it takes pulling up on the reverser levers to increase engine thrust to make the reversers effective.
I'm sorry, but this sentence makes no sense. You state that you pull up on the reverser levers to extend the reversers... but then that the same action, yet somehow different, will cause the engines to spool up? I think you made a typo and since I've never flown a plane, I'm not sure what you mean.
Could you kindly clarify?
Quoting David L (Reply 12): As was the HS Trident. It could achieve a decsent rate of ~10,000 fps if necessary, though the FE apparently had to work very hard to regulate the cabin pressure.
Why is that?
So my other question is that if you deploy the reversers before you cross the threshold and then you get hit by a gust of wind that throws your roll off or something, how are you going to get them stowed in time to do a go-around? He looked to be a good 10 feet AGL when they folded out. And in 2H4's photos, it appears that they are as much as 30-40 ft. AGL with reversers deployed. I know probably nobody here has every flown a Tu-154, but is it really THAT much of a bulldozer to stop?
he means: you pull on the thrust reverser lever. Then the thrust reverser will be activated, means the doors for the T/R start to open and the flow of the thrust will be reversed. But only idle. During this door opening you can pull on the T/R levers as much as you want, you cannot move them up any further. means you only have idle reverse thrust until the doors are fully opened, then this lock will be removed and you can pull on the T/R levers and adjust it from idle reverse to full reverse...
LY744 From Canada, joined Feb 2001, 5536 posts, RR: 11 Reply 17, posted (4 years 10 months 2 weeks 2 days 17 hours ago) and read 7204 times:
Deploying T/R before touchdown is standard procedure on the IL-62 (where only 2 of the engines have reversers), but I'm not aware of that being part of the Tu-154 SOPs. Of course nothing that a modern Tu-154/Il-86/Il-76/An-12/Tu-134/Il-62 crew does could surprise me anymore.
Point8six From United Kingdom, joined Apr 2008, 94 posts, RR: 0 Reply 18, posted (4 years 10 months 2 weeks 2 days 17 hours ago) and read 7185 times:
Reverse in the air , above 10,000ft, was approved for the HS Trident, as was full reverse in the flare (for short/wet/contaminated runways). I believe it was used on Concorde to reduce speed from supersonic to subsonic. I understand it was used on DC-8s with RR Conways - not sure about other engine types. I have seen it selected in the flare on a B747-400 - fortunately it did not deploy until "weight-on"
The example I heard (on TV) was from an ex-Trident Captain who was given an approach slot that required either descending that quickly or joining the back of a long queue. It certainly wasn't routine.
Quoting DocLightning (Reply 15): how are you going to get them stowed in time to do a go-around?
Good point. As Starlionblue says, I'm not aware of the other types mentioned deploying reversers at the same point as those Il-62 examples.
Quoting Point8six (Reply 18): I believe it was used on Concorde to reduce speed from supersonic to subsonic.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 20, posted (4 years 10 months 2 weeks 2 days 6 hours ago) and read 7067 times:
Quoting 2H4 (Reply 2): I wonder if such a procedure is officially approved and/or recommended in any flight manuals...
It's allowed on all 737NG's from the factory...whether an airline puts that into their flight manuals is another question.
Quoting Viscount724 (Reply 6): The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that.
Most low-bypass engines with bucket-reversers can be safely deployed in flight without a disaster happening. For high bypass engines with cascade or petal reversers, it's generally a bad thing so it's usually restricted to being on the ground or very close to it (at least on Western aircraft).
Quoting XT6Wagon (Reply 11): The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.
All 737NG's can do this too.
Quoting HAWK21M (Reply 14): Are you saying B734.
Why not Air-Grd sense.
You always want two air/ground inputs to make sure you don't loose reversers if an air/ground sensor goes bad. On Boeing's with multi-axel bogies, they use strut compression and truck tilt as the two inputs. 737's, for obvious reasons, don't have a truck tilt sensor. So they used the radio altimeter as the other input. You can deploy reversers if you're on the ground or if the radio altitude is less than 10'.
ThirtyEcho From United States of America, joined Dec 2001, 1634 posts, RR: 1 Reply 21, posted (4 years 10 months 2 weeks 2 days 3 hours ago) and read 7035 times:
Quoting 2H4 (Reply 4): The only I can think of off the top of my head are rather extreme flap settings in some older 172s and 182s that make landings a bit dodgy when operating at light weights. I think the combination of full flaps and light weights have set a lot of pilots up for nosewheel-first landings over the years.
Take it easy there, Astronaut; the 40 degree flap settings on the early Cessna singles were wonderful if one flew into short or rough runways, especially if one had to dive-bomb over tall trees near the approach end of a short field.
The 182 on landing is nose-heavy, even with NO flaps,
and can be wheelbarrowed by the novice quite easily.
Nomadd22 From United States of America, joined Feb 2008, 1561 posts, RR: 0 Reply 22, posted (4 years 10 months 2 weeks 2 days 1 hour ago) and read 7009 times:
Maybe he was an old Harrier pilot having a flashback.
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 23, posted (4 years 10 months 2 weeks 1 day 23 hours ago) and read 6957 times:
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Quoting ThirtyEcho (Reply 21): Take it easy there, Astronaut; the 40 degree flap settings on the early Cessna singles were wonderful if one flew into short or rough runways, especially if one had to dive-bomb over tall trees near the approach end of a short field.
Hey, no argument here! I've had plenty of fun with flaps40.
My point was simply that, over the years, that flap setting has set many less-than-disciplined pilots up for very bad days. To them, it's just another flap setting. In reality, it's an introduction to a very different set of benefits and pitfalls...all of which should be considered and respected.
Quoting ThirtyEcho (Reply 21): The 182 on landing is nose-heavy, even with NO flaps,
and can be wheelbarrowed by the novice quite easily.
Mark5388916 From United States of America, joined Aug 2007, 377 posts, RR: 0 Reply 24, posted (4 years 10 months 2 weeks 1 day 20 hours ago) and read 6923 times:
The C-5 Galaxy Also can deploy T/Rs in flight. IIRC, Its limited to FL240 when the T/Rs are out of service because it won't be able to descend fast enough otherwise..
Mark
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25 Avioniker: You have both brought up a once popular misconception. Actually it's to keep the nose from slamming down as a result of the heavy deceleration and tu
26 Kalvado: should it be 10 000 fpm? 3000 m/s is way too hypersonic..
27 Bellerophon: Reverse in the air, right down to touchdown, was approved on the Trident. There was no only above 10,000 ft restriction. Having said that, it was ver
28 Nomadd22: Dang. I was looking forward to that 7,000mph decent.
29 Point8six: There was a restriction on the use of reverse thrust on the HS Trident, during descent and it was a SOP restriction, that it had to be cancelled by FL
30 2H4: Sorry, I'm not quite clear on this....was the restriction put in place by the manufacturer, or by the airline? Well heck, don't leave us hanging...wh
31 Blackbird: I think it's pretty obvious that the Trident could do a 10,000 feet per minute descent, not 10,000 feet a second. Andrea Kent
32 Metroliner: T/R before touchdown, if an FS2004 manual for a Tu-154M is of any value whatsoever (please do note a raised eyebrow on my part) is supposedly discreti
33 David L: 10,000 feet per Saturday. What's wrong with that? On the other hand... oops! Indeed, I've only heard that one example of the use of reverse for such
34 DocLightning: Aha. Thanksey. I bet it could do 10,000 feet per second. You aim the nose straight down and select full thrust. Pretty soon... ...you win a Darwin Aw
35 Bellerophon: Point8six There was a restriction on the use of reverse thrust on the HS Trident, during descent and it was a SOP restriction, that it had to be cance
36 Point8six: Bellerophon - you obviously still have your Trident manuals -( mine are probably still in the loft of a house I moved from nearly 30 years ago!) and s
37 David L: We're sitting comfortably.. you may begin.
38 JoeCanuck: I saw a show that descent reverse thrust is available on the C-17.
39 Tdscanuck: It wouldn't surprise me...the C-17 can do a lot of things that a commercial jet can't do, primarily to achieve the desired short field performance. T
40 Starlionblue: It is. By using idle reverse and deployed surfaces the C-17 can descend at 15000 fpm if memory serves.
41 Bellerophon: Point8six Thanks for the detailed reply, I'm glad it was you and not me, as it must have been quite worrying for a while. The impartial management inv
42 Point8six: You flew the Trident simulator voluntarily, until recently? I'm sending the men in white coats around.
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