Engine thrust level for deploying thrust reversers

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  • Engine thrust level for deploying thrust reversers fooot

    Does an engine have to be at idle thrust for the reversers to deploy? If the engine is at higher than idle thrust, will it slow down to deploy the reversers and then speed up again, or can it just deploy the reversers at the higher thrust?

    I am also asking about turboprops going into beta range.

    I had this question based on the discussion on this question:

    What to do when you accidentally land on a runway thats borderline long enough to land on?

  • Engines must be at idle thrust to enter reverse thrust. This may not be 100% true of the physical action of engine entering reverse thrust (opening the buckets or translating the cowling), but it is required by the thrust levers. In all airplanes I'm familiar with the thrust levers must be at idle to enter the reverse regime, In the EMB-145 the reversage was below idle (i.e. you keep moving the levers aft) through a gate. Even if the engine is capable of entering reverse thrust not at idle, there is no way to command it without first being at idle.

  • On 747-100 and -200 aircraft, each reverse thrust lever is mounted on the front side of it's respective thrust lever with the hinge above the reverse lever's end knob. If you should happen to grab the reverse thrust lever without having the forward thrust lever all the way back, the action of lifting the reverse thrust lever will force the forward thrust lever all the way back. When you lift reverse thrust lever to an almost-level position from it previous position parallel to the forward thrust lever, the buckets come out. That in itself provides considerable braking, and it's common to stop there. Continuing to lift and then bring back the reverse thrust levers spools up the engines. You need to be careful doing this. Coming back too far too fast might cause a compressor stall, especially on an already marginal engine. Compressor stalls on a Pratt and Whitney engine are no big deal. On a General Electric engine they are far more serious. As I remember, there was a lock-out that prevented an engine from moving into reverse thrust from other than idle thrust, but I can't remember how it worked, but I believe it required not just idle thrust but the aircraft also being on the ground (squat switches) and landing flap deployment.

Related questions and answers
  • Does an engine have to be at idle thrust for the reversers to deploy? If the engine is at higher than idle thrust, will it slow down to deploy the reversers and then speed up again, or can it just deploy the reversers at the higher thrust? I am also asking about turboprops going into beta range. I had this question based on the discussion on this question: What to do when you accidentally land on a runway thats borderline long enough to land on?

  • Anecdotally I have heard of various things that I can do to make steel brakes last longer before they have to be replaced, and they make sense but how much does it really help? Things that I have heard: Land at the minimum recommend speed Use maximum reverse thrust (if you have it) Delay braking after landing (if on a sufficiently long runway) to allow slowing before brake application Various taxi techniques (taxi on one engine, don't ride the brakes, but instead build up speed and then brake to slow down. Rinse and repeat.) Are there any studies that have been done to show how much

  • According to Airbus: ‐ After the flight crew selects reverse thrust, they must perform a full stop landing. Does it really make sense to have this limitation, and why? What happens if you realise there's not enough space to land, and you've still got adequate speed?

  • might not get to use the machine again, and you might spend some time in hospital, you would live to fly another day. I am assuming a reasonable place on dry land is available to finally come to rest...When I learned to fly helicopters, I of course spent significant time learning about and practicing autorotations. The CFI at my school, who had around 15,000 hrs (that's right, fifteen thousand!) said a few times that practice, knowledge and currency are vital — but as long as you got the entry right (following which you can fly to the ground) and executed at least a decent attempt

  • The reason for my arguments here are (assuming that you have sufficient runway distance): That with less thrust, less force should also be required to hold the aircraft as desired, and possibly the aircraft should be easier to control and fly when the engine fails than if it does so with the thrust set to full blast. An engine event, such as a bird strike, might (?) be less likely to have catastrophic consequences for e.g. the turbine blades when they are not running at full thrust and their design limits. Never having actually commanded an aircraft, are any of these ideas correct?

  • Non-precision instrument approaches generally have altitude restrictions which get lower when you get closer to the airport. I always figured these restrictions were AMSL using the current altimeter setting, not compensating for temperature. Some have heard the mnemonic that mountains are higher come wintertime, which basically means that colder weather make your altimeter read higher than you... you're free to fly higher if it's a particularly cold day. But have a look at LOCKI intersection, the final approach fix. That's at 1500 ft, not at-or-above. At -40, this will put you around 1100 ft above

  • short of the far end of the runway (which, btw, ends in a cliff. Just to heighten the suspense). I'm sure they had their reason, so I'm not going to question them. I just wanted to use it as a set up for this question: If you accidentally touch down on a runway that is borderline long enough to stop your aircraft on, how would you determine if you wanted to either stop or just do a touch and go...I was reading another question earlier when I noticed a story about a 737-700 that landed at M. Graham Clark Downtown Airport in downtown Branson Missouri. The runway is only 3738 ft, long, which

  • If you fly low, air is dense so you can get more thrust from your engines, but you get more drag. On the other hand if you fly higher you have less drag but the output of engine decreases as well. So what's the optimum altitude to fly at, and how does one determine it?

  • When flying on a long-haul flight, you can often see gate allocations for when you land a hour or two before actually arriving at the airport, including transfer information and connecting flights. However, with so many aircraft and frequently changing situations, how do they manage to allocate these gates so far out in advance?

  • I know on the 737, the leading edge slats deploy at the first flap setting, and the trailing edge flaps deploy after that at higher flaps settings. Why do the slats deploy before the trailing edge flaps?

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