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Reversers on in midair

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Is this possible in real life? If so, what would happen to the a/c? I mean about the B-737,57,67,77, A320Series, etc... I have seen shots of some russian airliners do it...Thanks for any info!Z

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If I recall correctly, some years ago a JAL pilot chose to commit suicide in a novel way, by deploying his reversers while on final into Tokyo. The plane crashed into Tokyo Bay. Does anyone else remember this incident?

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This article suggests that deployment of such devices send the plane in to a sort of spin ("rapid torquing"), and ultimately the a/c would crash. I found this on google.http://abcnews.go.com/sections/us/DailyNew...ters110299.htmlI thought that reversers could only be activated while on the ground (by way of devices called "squat switches" which would lock the reversers unless the weight of the a/c against the runway pressed on them), but I guess I was wrong.

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But how is it with turboprops. If I'm right I recall reading about twotters deploying reverse trust (not standard procedure) for ultrashort field landings and/or very steep landings..http://www.emotipad.com/emoticons/Headspin.gif

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Yes I believe there are some older airliners with specially designed twin engine clusters, in which one of the engines on each side can deploy reverser buckets in flight to act as a type of speedbrake to increase descent rates...but I believe this is rare. My father is an aeronautical engineer who did some consulting for one of the airlines over a concern that an inadvertant thruster deployment in flight might happen, I think it may have been for the 747. Anyway, it is bad, very bad, for the airplane should the interlock systems fail for some reason and the thrusters are deployed at any time that the airplane isn't on the ground...regards,

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Hi,the (old) DC-8 was allowed to use 2 of its 4 engines on inflight reverse for speed reduction (e.g. during a high rate of descent).On the props, there are a bunch out there, mostly STOL capable aircraft, able to have a "beta range" on their props: (Twin) Otters, Pilatus Porters...Most prop aircraft don't need it, however, since the prop itself is a huge source of drag when feathered.Torsten

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That's true, then they found that Twin Otters and Turbo Beavers started crashing because of it. They then installed a "safety switch" of sorts, whereby you had to have 40% FWD power before you could get it into reverse. That really screwed up some folks in the beginning as they used to power-back those machines off beaches and whatnot. That became a whole lot more difficult, especially when pulling away from docks where you weren't already anchored.The squat switch was for spoiler deployment. For quite a while there, following the crash/burn of a DC 8 at Toronto (CYYZ) because the spoilers deployed at about 50 to 100 feet agl above the runway, you couldn't even arm the spoilers on approach. Now I believe the systems will allow that, and the squat switch has several redundancies, if I'm not mistaken. The Fokker F28 and BAe 146 use a different type of spoiler system, whereby they are like little flaps that stick out horizontally from the rear of the fuselage and destroy speed more than lift. These are used more to slow them down rather than dump the lift, and are used in the air. I guess they are more speed brakes than real spoilers.Glenn

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I think that in flight reversers are possible on the C17.Joel

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NASA uses Lear Jets in a dive with reverse thrust deployed to simulate shuttle landings, with no engines. The reversers are deployed to ack like the flying brick the shuttle acts like.

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Alrighty now...TOO MUCH MISINFORMATION IN THIS TOPIC...Sorry for the CAPS, but it's needed.1) Thrust reversers are NOT deployable in the air on ANY AIRCRAFT. In the case of the Lauda Air crash, there was a failure of the isolation valves that prevent the reversers from actuating inflight, which caused the reverser to open under AERODYNAMIC PRESSURE, it was not commanded, nor was it forced open. There was simply no pressure in the lines to hold it closed. In the JAL crash, that was speculation. Like I said, you CANNOT command the thrust reversers to actuate in flight. On all Boeing aircraft EXCEPT the 757, the nose squat switch MUST be depressed for reverser operation. On the 757 ONLY, the reversers are linked to the mains as the rudder on the 757 is so large that it allows for enough controlability with the nose off while under reverse thrust, even asymetric reverse thrust.2) The reversers on the early JT-3 and Conway powered DC-8s (-10 through -40 series aircraft) did not deploy in air, only the silencer rings, and ALL 4 could be operated. The later JT-3, JT-9 and CFM powered versions did NOT have this ability. The GROUND spoilers are just that, for the GROUND. Douglas installed the squat switch after an Air Canada crew attempted to use them in the air to slow down (at ALTITUDE, not on approach) and the aircraft broke up under the resultant stresses.3) Reverser deployment is not possible in flight on the C-17 for the simple reason that it'd rip the engines off their pylons. They are fast-acting reversers, so they'll open immediately after touchdown and it may seem like they're using reversers in the air.4) NASA uses specially modified GULFSTREAM II-SP aircraft where the normal target-type reversers (also called bucket reversers) are replaced with enclosed clamshell-cascade type reversers (like on the 727) to reduce the stresses on the engines and remove the buckets from the airstream (they'd rip off if they used buckets), and they have seriously re-enforced the engine pylons to take the stresses. The aircraft also deploy their main landing gear in the "Shuttle Mode", and the flaps and ailerons have been modified into Flaperons to increase the maneuverability of the craft and better simulate the handling of the Shuttle.5) Glenn, you're mostly correct on the F-28/-70/-100 and BAe RJ series aircraft. They still have "lift dumpers" on the wings that will spoil the lift on the ground, the tail is a speedbrake alone like you said. However, most aircraft nowdays have spoilers of a new kind. They're split into two categories- Flight Spoilers and Ground Spoilers. Flight Spoilers are used for speed reduction and roll-augmentation. Ground spoilers only deploy on the ground to dump lift off the wing and keep the plane from bouncing too much. A great example of this is the B-1B. Each wing has 4 spoiler panels. The outboard pair on each wing can be deployed at up to 40 degrees for roll augmentation and 75 degrees as an inflight speedbrake. The inner pair only deploy on the ground once momentary pressure has been applied to the nose gear and are purely for lift dumping. Many commercial aircraft have similar setups.Thanks for reading this guys. Only thing I request is that you guys do some research before providing answers and confirm what you think you know. It only takes a few minutes and saves on a lot of confusion.:)

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Aw thanks for clearing that up Chris, I knew it was some type of Biz Jet that NASA used, but I thought it was a Lear not a Gulf.

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DC8 did it on the two inboard engines, some B727 jocks did it as well when it was first introduced but had some jet upset problems. I have seen it done on the russian TU-154 deploying the reversers on short final on the two outboard engines, but I have also seen them blow a few tires as well upon landing in that configuration.When you feather the prop you are removing the drag induced by the windmilling propeller.Chris de Barros/MYNNBahamasair DHC8-300

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Actually I've just done some research today as I'm sitting here with a maintenance training manual for the learjet 35 :-) To activate the reversers on a lear 35 you first have to arm the reverse-thrust mode, turning on power to the reverse-thrust systems. When the system is armed, sensors coupled to the wheels and thrust requires these to have ground contact/idle thrust set. Not until then are you able to activate the reversers. So I think it's pretty foolproof in that case :-) Although if my memory serves me right, there where a couple of incidents with the saab 340 some years ago with pilots reversing the engines in mid-air, I think they changed the throttle-levers a bit after that... Maybe someone else knows something more about this? Would be fun to know!rgrds/fredrik

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Correction: NASA uses Gulfstream II aircraft specially configured for shuttle training.

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The TRs on some aircraft are squat switch activated while others require a switch in cockpit to be activated to arm "buckets". As a rule, the higher the aircraft's speed the more effective the buckets. The worst case is for a single bucket to deploy on an aircraft with wing mounted engines.

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Correction: The activation of thrust reversers in-flight are not certified or authorized in flight on any aircraft. There are aircraft that it is possible to deploy reversers. The Sabreliner for one has that ability and, while foolish, has been done. It just creates an amount of drag that few can reliably deal with. Hence, the limitations.

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Christopher,I'm not saying others may not be off on the facts, but the DC-8-6x for certain did have the ability to deploy reversers in flight, as I've experienced first hand inbound to Milan from JFK back in '77. The pilot even announced the procedure as such--mostly because he was concerned that the vibration and racket it made would concern the pax. It gave the physical sensation of hitting the brakes very hard--and since we were over a cloud deck, an uncanny feeling of standing still. I grew to question this several years later when someone said it wasn't done. I found that it indeed was with the DC-8-6x--can't vouch for the older models...Only other thing I got out of the flight--you don't want to fly westward in a DC-8 super 60. We had to refuel in Shannon and Gander on the return. Longest pond hop I've ever made.So with good humor I say:Thanks for reading this . Only thing I request is that you do some research before providing answers and confirm what you think you know. It only takes a few minutes and saves on a lot of confusion.:-beerchug

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See my post above. I said exactly that.Pet peeve #1- People posting duplicate information.

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Actually John, if you'll go over to the HJG forum and search through their topics, Dee Waldron, a DC-8 MECHANIC has stated on several occasions that such a procedure was NOT authorized or condoned by Douglas and required modification of the aircraft control systems. If you attempt to deploy the inboard reversers on one of the HJG DC-8-6x aircraft, you won't be able to for that exact reason. I've tried it. You have to go and modify the MDL, AIR, and Aircraft.cfg files to do that, just as you'd have to modify the aircraft.I did do my research. Unapproved modifications by the operator are not included in that research.

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"Unapproved modifications by the operator are not included in that research."Well, I have no way to refute that--no way of knowing if the airline I flew on (TransInternational) had applied any mods or not. Since they were a charter airline, I suspect they were not the original owner of the aircraft, and I believe the aircraft was subsequently sold to Arrow Air. When I heard of the DC-8 crash in Canada, I've always wondered if it were the same aircraft. TIA didn't have a very big fleet of them...Also, I know of no .cfg or .air mod that will make the reversers deployable in flight in FS2000 or FS2002, although FS98 had that ability without any mods at all. The .mdl file would only influence visuals--not the ability to actually simulate the procedure.-John

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"2) The reversers on the early JT-3 and Conway powered DC-8s (-10 through -40 series aircraft) did not deploy in air, only the silencer rings, and ALL 4 could be operated. The later JT-3, JT-9 and CFM powered versions did NOT have this ability. The GROUND spoilers are just that, for the GROUND. Douglas installed the squat switch after an Air Canada crew attempted to use them in the air to slow down (at ALTITUDE, not on approach) and the aircraft broke up under the resultant stresses.Well sir, with all due respect, I SAW the Air Canada accident and the subsequent accident reports (I believe it happened in around 1968, but I may be out a couple of years on that). At that time, the spoilers could be armed (but not deployed - air brakes yes, but not full spoilers). The DC 8 copilot armed the spoilers as was usual on approach in those days (still is, but with a difference). For some reason, the spoilers fully deployed (spec was either the squat switch failed or something triggered the spoiler mechanism into thinking that there was a WOW situation) at about the 100 to 50 foot agl altitude, and the airplane made a very hard landing with a subsequent bounce to about 50 feet in the air (roughly) again. As per emergency drills, the captain applied go-around power and proceeded with a missed approach. Just as he did, the fire alarm went off for the No. 4 engine, and it was showing that they had lost the engine (at that time, the pilots believed the engine had simply failed). They proceeded to shut down the engine and continue with the missed approach, not realizing that in fact the engine had separated from the wing, with the wing actually being on fire (I believe it was a stretch-8 and that would mean the Copilot would have to really crank his head around to see the wingtip, not something he was going to do at this busy period). The aircraft starting making a slow (initially) descending right turn on at some point in the climbout, as the wing then became quite rapidly engulfed in flames. Shortly thereafter the aircraft crashed in an area near Woodbridge, just north of Toronto. All were killed of course.As a result of the accident, spoilers were mod'ed such that they could not be armed at all in flight, and the FO or PNF would have to manually extend the spoilers once touchdown had been accomplished. This persisted for some years, but has since been mod'ed again to allow for in-air arming. The newer systems have multiple redundancies and safety switches which makes this manoeuver much safer now.On the reverse operation in Twin Otters and Turbo Beavers, I know about this because I was flying Beavers myself in northern Canada, and all the guys that were flying for the MNR that I knew at the time, were showing me how the new setup worked. What happened was that some pilots were trying to make extremely short landings and they were actually engaging a minimum amount of reverse thrust (pitch, if you will, given these are turbo-props) on very short final, but a few guys got carried away and started the reverse action a bit too soon. This caused a few hard landings and one or two aircraft being written off (or close to it). As a result of that, a mod was completed that would not allow reverse to be engaged until the engines were spooled to about 40% power (I don't recall the exact mechanism by which they did this though). I got to be funny watching some poor soul who had yet to get used to this feature, trying to reverse out of a dock or off a beach, only to find himself getting stuck on the shore as a result :-).OK, how do I know all this? I was there, I was a RW pilot for 17 years, and I'm now an avionics tech :-).Glenn

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Okay-I stand corrected. In-flight thrust reverse was approved on the -62 and -63 models ONLY in the later series of models. These were the aircraft equpped with the T-ring/Bucket reversers. The -50 series and the -61 models which had the cascade-type with the "window blinds" were not approved for this procedure due to problems with the blinds breaking off in flight. I misread the statement by Dee on what aircraft were approved for that procedure.

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Actually, I never questioned anything on the Otter and Beaver thing. That's something that was told to me as well by my flight instructor, who has a lot of time in Super Twin Otters during his career.As for the DC-8, that's one I hadn't heard of. I had only heard of the Air Canada one that broke up at 20,000+ when the crew tried to use the spoilers in flight to slow the plane down. However, the DC-8 has NEVER had in-flight speedbrakes. Only ground spoilers and while they could be extended in flight (they weren't originally fitted with a squat-switch interruptor), it was NEVER approved. They were designed as ground spoilers and that was what the manual has them as. If you have any question to this, feel free to go download one of HJG's DC-8s and read the included documentation. Even better, go to their forum and ask Dee Waldron, an A&P mechanic and the guy who put that plane together, about it. You're right about the mod on the -40 series DC-8s however. For a time, the -40s did not have a squat switch arm or anything, and had to be deployed manually, however most of the other aircraft in the other series' simply had the ground squat switches installed and thus inhibiting any deployment of the ground spoilers in flight.Edit: The information on the spoilers and their use has also been verified by a current UPS DC-8 mechanic of 30+ years experience with the DC-8 and several other series of aircraft.Edit(2): Forgot to mention that the primary approved method of reducing speed in the air was to extend the landing gear. They had a very high Vle, so they could be extended in most situations without concern of overstressing them. This is also reflected in the HJG DC-8 documentation and confirmed by the same UPS mechanic.

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While flying aboard a UAL DC-8-71 (CFM Engines) from Orlando to Denver in May 1987 the Captain used the inboard reversers to "expedite our descent" into Denver. It was as described in an earlier post, lots of shaking and noise. I saw 'em deployed - but I didn't get a t-shirt.RobertVirtual Thorp T-18: http://home.nethere.net/kerr/virtual.htm

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