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Guest BC_KBOS

Reversers on in midair

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Guest MikeEppright

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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Guest MikeEppright

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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Guest ChrisTrott

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

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Guest ChrisTrott

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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Guest

"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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Guest ChrisTrott

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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Guest ChrisTrott

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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Guest BC_KBOS

Chris,Not to be completely morbid, but I guess you never saw the Mexican (I believe) DC-9/MD-80 that had the mid air over San Diego.In the picture that was published, you can clearly see the reversers deployed in the Captains vain attempt to arrest the descent. I am fairly certain it was Aero Mexico, could have been PSA, but I think it was Aero Mexico.Horrible example of reverser use in flight, I know, but they are available on certain aircraft. At least they were.BC

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Guest AJ

Afraid you are mistaken about the C-17. This is direct from the Boeing Website:"The four engines are Pratt & Whitney PW2040 series turbofans, designated as F117-PW-100 by the Air Force, each producing 40,440 pounds of thrust. The engines are equipped with directed-flow thrust reversers capable of deployment in flight. On the ground, a fully loaded aircraft, using engine reversers, can back up a two-percent slope." Seehttp://www.boeing.com/defense-space/milita...17/c17_back.htm

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Guest

Concorde can deploy its inboard thrust reversers in flight as well, can increase the rate of descent to up to 6000fpm without gaining speed, often used inbound to JFK.

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Guest tcable

Concorde is also able to deploy the reversers in flight- doing so is by activating reversers by the FE with a switch and then only the inboards may be used at idle reverse. This is a common practice for Concorde when an expidited descent is required- there are no aerodynmaic speedbrakes or control surfaces other than elevons and the twin rudders.Tim

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Guest AndrewW

Actually it's not common practice for this procedure to be used on Concorde, only in a situation such as the one Tim has described above. The inboards are only placed into reverse idle when below 30,000ft, and below 370Kias. This can increase the rate of descent up to 11,000fpm! Maybe used only around 10 times in a pilots career on the fleet! The more common way to increase the rate of descent would be to perform what is called a 'spill door descent'. Andy[/font size]

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