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JSACKS

What does "idle reverse thrust" mean?

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I don't understand how reverse thrust can ever be "idle". Is it not dynamic by definition? What am I missing?Jonathan


Jonathan Sacks

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Guest Ryan Briggs

Idle reverse thrust means exactly that, the thrust reverser is unlocked but the engine is idleby pulling up on the thrust reverse levers it unlocks them, they click into an unlocked state then smoothly pull back to the Maximum N1/EPR the thrust reverser is rated for the pilot can control how much reverse thrust he is getting the further back he pulls the levers before he closes them however its ideal to have the engine at or near idle so they are pushed forward to just before the "Closed" position once the engine spools down he clicks them back into place and the reversers are closed

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In addition to Ryan's excellent in real world situations, some jetliners increase taxi speed too fast even with idle thrust. By "opening the buckets" the idle reverse thrust gives just enough reverse thrust to slow the aircraft avoiding frequent brake application.Another real world use is if you are starting in a moderate tailwind, the turbines will be free spinning in the reverse direction. Deploying the reversers will shield the turbine fans from spinning in the incorrect direction reducing the load on the bleed starter system.I am not sure how FS handles opening the clamshells or buckets while still maintaining idle thrust.


Ron Ginsberg
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Deploying the reversers will shield the turbine fans from spinning in the incorrect direction reducing the load on the bleed starter system.
Interesting concept. Is this an approved technique? (sounds risky) :(In theory, if EEC logic allowed it, I guess it could be done on 744's with pneumatic reversers as well as hydraulic reversers, but you'd have to deploy the reversers prior to starting the engines.Cheers.Q>

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Guest hangar744

Good day,no a/c type was mentioned above, so let me describe how it goes on 744.For normal operation of the thrust reversers, you will need to meet a few requirements.- ground mode- engine in question running- fire switch in question in its normal position- electrical power- pneumatic (hydraulic power for PW4000)Failure to provide any of the items above will result no thrust reverser movement.***Another real world use is if you are starting in a moderate tailwind, the turbines will be free spinning in the reverse direction. Deploying the reversers will shield the turbine fans from spinning in the incorrect direction reducing the load on the bleed starter system.***Turbine fans? I'm not sure what you mean with that/those.This cannot be done on a 744, since your engines are not running (condition #2). The starter motor is powerful enough to cancel the reverse spinning. Maintenance has procedures to "fool" the bird, so we can operate the T/R's without starting the engine.Note: My PMDG reversers operate by means of hydraulic power regardless of engine type. My PMDG reversers (GE & RR) have nothing to do with the pneumatic system. My PMDG reversers can be operated with engines not running. My PMDG reverse thrust levers can be advanced above the reverse idle detent while the thrust reverser is in the stowed position. My PMDG engines play reverse thrust sound when I remove hydraulic power and I move the reverse thrust levers out of the idle stow position. This last one is rather unusual.Qavion...can you confirm these strange behaviors, please. I experience them with FS9 744 and 744F.Do not get me wrong, I really have a lot of fun with this kite.regards,delcom

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>This cannot be done on a 744, since your engines are not>running (condition #2). Maintenance has procedures to>"fool" the bird, so we can operate the T/R's without starting>the engine.Pilots can "fool the bird", too.e.g. with RR engines.Select Autostart.Pull Start switch (this will reverse flow the PRSOV engine valve allowing APU air to get to the starter motor). Select reverse (Reverse will deploy)Presumably, if you lift the fuel cutoff lever, the engine will begin a normal Autostart.... unless, as I said, the EEC has logic to prevent it.If Autostart didn't allow a start, then maybe a manual start could be carried out after the reverser had been deployed using the Autostart switch.I haven't any data on tailwinds during start (as the Maintenance Manual specifically states that for engine test runs, the aircraft must be pointing into the wind). The Roller EEC won't allow an Autostart if the N1 is not spinning fast enough in the right direction during start.PMDG system logics are based on P&W engines, and I haven't been trained on the P&W 4000, so I really can't comment on the other stuff.Cheers.Q>

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It was the tech-ops forum at airliners.net. that mentions starting in a tailwind with the reversers extended. It was not a Boeing but I just wondered if it can be used when starting engines in a strong tailwind beyond specified limits.http://www.airliners.net/discussions/tech_...ilwind#ID191298I should have used the term turbine or compressor blades.


Ron Ginsberg
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Guest hangar744

What I found about GE so far:Starts conducted with tailwind velocity components exceeding 25 knots may produce hot starts.***Pilots can "fool the bird", too.***True. Everybody who's familiar with that procedure.My last experience asking the pilots to "fool the bird" was ineffective. Either they've never heard of the procedure you described above or simply they did not feel confident about it. Don't ask. They didn't want to follow my instructions. So we just waited for them to leave the aircraft, then we could troubleshoot the T/R. I found it strange, too.regards,delcom

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