reverse thrusters

[CrewResearch]

Thrust Reversers

Thank you for your replies to my questions. I appreciate it.

Weasil -- thank you as well for correcting my use of the term reverse thrusters -- I was going by the original title of the thread. Can I correctly say that Thrust Reversers (the system) create reverse thrust (the effect)??

I can imagine that routinely powering back would indeed unnecessarily burn a lot of fuel, and, as you point out, end up costing the carrier a lot of money over time.

bafanguy -- When you say:

"However, policy did allow use of idle reverse to assist the tug during pushback on a clippery ramp after coordination with the ground personnel." [my emphasis]

do you mean warning the ramp folks, for safety reasons? or getting clearance for that from dispatch? or both?

User997 gave the example with the Citation. In general, would this kind of practice be more common with corporate/GA aircraft than with commercial a/c?

 

[EagleRJ]

The cost of powerbacks is not in the extra fuel, which is negligible. It is in wear and tear on the thrust reverser mechanisims and the stress on the engines. When in reverse at zero airspeed, an engine tends to ingest some of its own exhaust, which makes the ITT go up and adds the equivalent of several takeoffs to the engine in terms of wear.

Useless trivia:
Does anyone know the only airplane that can back up on the ground, even though it is not equipped with thrust reversers or reversing propellers?

 

[User546]

User997 gave the example with the Citation. In general, would this kind of practice be more common with corporate/GA aircraft than with commercial a/c?

I should clarify that this is not a very common practice, and is only used in rare situations.

While being used for landing, the thrust reversers should be re-stowed upon decelerating thru 60 knots, to eliminate the possibility of foreign object ingestion.

It's even more of a possibility for ingestion when using the reverers on a ramp from a stand still. So you should always use caution when doing so, and only do it when absolutely necessary.

But sometimes you just gotta do, whatcha gotta do....

 

[Weasil]

-- I was going by the original title of the thread. Can I correctly say that Thrust Reversers (the system) create reverse thrust (the effect)??


"However, policy did allow use of idle reverse to assist the tug during pushback on a clippery ramp after coordination with the ground personnel." [my emphasis]

do you mean warning the ramp folks, for safety reasons? or getting clearance for that from dispatch? or both?

That's fine.. I know the thread title was not quite correct, just trying to feed you correct info. And yes your statement is correct - thrust reversers create reverse thrust. The air flow normally flows front to back through the engine and reversers direct that airflow (by different mechanical means like blocking doors and guide vanes for example) forward to assist with deceleration.

When pushing on a slippery/icy ramp we usually wait until pushback is complete because even idle engine thrust will often stop the tug from pushing us backwards.

As to your last question - ground personnel assist with engine starting by telling you when it's safe to do so - they are your eyes and ears because you can't see what's back there from the cock pit. All engine starts are coordinated with ground personel at my airline. Often just by use of hand signals and sometimes by use of interphone (if they plug their headset in to the outside of the airplane).

 

[Jeff Helgeson]

They are TR, not RT!

Thrust Reversers are the proper term and the most common. They are often referred to as TRs. I don't like that because the DC9/MD80 has Tranformer Rectifiers (Right TR1, TR2 and Left TR1 and TR2), which can be confusing out of context.

Lighten up!

 

[minitour]

Useless trivia:
Does anyone know the only airplane that can back up on the ground, even though it is not equipped with thrust reversers or reversing propellers?

Under it's own power??

It is an airplane correct? I haven't a clue...sounds cool though.

-mini

 

[FarginDooshbahg]

Thrust Reversers are the proper term and the most common. They are often referred to as TRs. I don't like that because the DC9/MD80 has Tranformer Rectifiers

So do most all transport jets. How else to you get 28VDC from an airplane that generates 115VAC?? Wait, I remember now. Something called PFM.

 

[bafanguy]

bafanguy -- When you say:

"However, policy did allow use of idle reverse to assist the tug during pushback on a clippery ramp after coordination with the ground personnel." [my emphasis]

do you mean warning the ramp folks, for safety reasons? or getting clearance for that from dispatch? or both?

CrewResearch,

Just a discussion with the tug driver as reverse isn't actually being used to move the airplane but just to cancel the idle forward thrust, making the tug's job easier on a slick ramp. The reversers are just placed in the reverse thrust position while leaving the power at idle.

Got the PM...agree with all you said. Thanks.

 

[EagleRJ]

Under it's own power??

It is an airplane correct? I haven't a clue...sounds cool though.

-mini

Completely under its own power, and yes- it's an airplane.

Hint: it doesn't move backward in a straight line....

 

[TedCFII]

I've noticed that it's pretty SOP at NWA with the -9's.... I see it every day in DTW.

 

[JAFI]

.

Useless trivia:
Does anyone know the only airplane that can back up on the ground, even though it is not equipped with thrust reversers or reversing propellers?

The mighty B-17

JAFI

 

[Immelman]

Completely under its own power, and yes- it's an airplane.

Hint: it doesn't move backward in a straight line....

Okay I was going to guess the V-22 Osprey but you're thinking something more strange for sure.

 

[User546]

I'll take a stab here...

EDIT: Removed answer, to embarassing of choice on second thought!

 

[EagleRJ]

JAFI's got it.

Crews in the Fortress could bring the #1 or #4 engine up to full power while locking that side's wheel brake, and the plane would yaw, causing the other wheel to roll back a few feet. By alternating that procedure, you could slowly back the plane up into a parking spot. Crews did that to cope with tight parking situations at the airfields in England.

 

[mar]

Had me stumped. Good one.

But, yeow! That's rough! Hopefully that was a last resort option as well.

 

[typhoonpilot]

JAFI's got it.

Crews in the Fortress could bring the #1 or #4 engine up to full power while locking that side's wheel brake, and the plane would yaw, causing the other wheel to roll back a few feet. By alternating that procedure, you could slowly back the plane up into a parking spot. Crews did that to cope with tight parking situations at the airfields in England.

It's not the only plane that has done it though. My dad did it in a B-24 in early 1945 on his way to England. He tells the story a lot better than me ( obviously, he was there ). Essentially they had to back out of a tight spot in Canada with no other method available to them.


TP

 

[Patriot328]

It's not the only plane that has done it though. My dad did it in a B-24 in early 1945 on his way to England. He tells the story a lot better than me ( obviously, he was there ). Essentially they had to back out of a tight spot in Canada with no other method available to them.


TP

Exactly. I'd imagine that thoretically, any airplane with its engines outside of the landing gear can do it. The Dojet will do it.

 

[Goods2000]

the reason they roll forward is to be sure that the nose wheel is locked straight before powering back, it is also still a common practice in the Md80 and DC9 if they are certified to do so for their company

 

[Goods2000]

Do you have the opspecs on board (I'm doubtful), or do you have to call dispatch to read/interpret it, for something that is rarely used and maybe forgotten?

It is required under part 121 and 135 to have a current ops specs and GOM on board during all operations

 

[Goods2000]

We've used it before (Citation II) to back into a parking space after arriving at our destination after the FBO closed and no one to push us back.

you backed up a Citation II ? did you have wing walkers, proper training and..... what is the minimum speed in the C500 for TR deployment

one final thought, who paid for the paint job that you destroyed on the airplane you were "flying "

 

[j41driver]

...so is that a "yes, that's what it's called"?

Yes.

And why do I have to put "at least 5 characters" in my message if all I want to say is "Yes"???

 

[minitour]

Yes.

And why do I have to put "at least 5 characters" in my message if all I want to say is "Yes"???

I dunno...

 

[User546]

you backed up a Citation II ? did you have wing walkers, proper training and..... what is the minimum speed in the C500 for TR deployment

one final thought, who paid for the paint job that you destroyed on the airplane you were "flying "

Goods, I can't help but feel your being fesecious in your reply, but I will respond to your reply none the less. You must not fly charter or corporate, cause if you did you would understand sometimes you have to improvise a little bit to get something done.

I stated "sometimes, you gotta do, what you gotta do" and although I don't believe in doing things that aren't recommended, sometimes all you can do is improvise.

We arrived at an FBO at an uncontrolled field at 11:00pm one night. It was a small ramp with parking only on one side, where a couple of smaller airplanes were parked. The airplanes were spaced far enough apart not to be in danger, but they were also jsut close enough we couldn't "turn" into the parking spot. So we did the best job we could and got it turned to where it could be backed into the spot. Unfortunately, that left us smack dab in the middle of the ramp, blocking any traffic that would try to come in or leave tomorrow.

Having cleared both sides and behind us on the taxi in to make sure nothing was in the way, we activated the thrust reversers for just a couple seconds and we very nicely backed right into our spot, far from being close to hitting the two planes on either side of the wing.

As discussed previously, 60 kts is the minimum speed at which the TR should be deployed, or stowed on a deceleration. And as stated in my previous case, I do understand its so that foreign debris doesn't get ingested. But what were we to do in that situation.

So, if you were in our situation, how would you have handled that differently? And I'm asking seriously, not argumenatively.

 

[Diesel]

King air I fly we use Reverser's to back up the plane all the time. Especially this one airport we go to. It's how we get into our parking spot. Middle of nowhere and line service is you.

It's not the same as a jet but the props take a serious sand blasting.

One night when i was in the 200 my boss went down the wrong row of parked planes. The tower asked him if he needed to send out a tug to get us turned around. My boss said nope. I got it. The tower said it was the only time he'd seen a plane do a 3 point turn to get out of HVN.

 

[User546]

The tower said it was the only time he'd seen a plane do a 3 point turn to get out of HVN.

Now THAT would've been a sight to see right there!

 

[Goods2000]

I understand the dilema, however, the power required to go from a stop to rolling backward is not only a FOD issue, all of the little rocks, sand and what not on a ramp will get kicked up and onto the aircraft.

A few seconds of TR's will not be enough to move you backward, It would require a fairly lengthy application at a high power setting.

If your only option is to park in the middle of the ramp so be it, either call in the night line personel, or if none are available, leave the aircraft parked and leave a contact number for you to be reached at if someone has a problem with where you are parked. I think it is a better option than potential damage to a multi , million dollar aircraft and engine

That is how I would handle the situation

 

[Diesel]

The even more crazy part was it was at night.

Remember don't touch the brakes.

 

[User546]

I'm not for sure if you ever flew a jet before with TR's, but YES they can be moved backwards (especially a lighter corproate jet) while using the reveresers for a short period of time.

There were no million dollar aircraft around, and probably the most expensive plane on the ramp was a 70's model 172. Far enough away that they wouldn't get blasted by sand, rocks, etc. I dont know if your thinking of this as a traditional ramp, but the "backside" of the parking spot was all grass, then a taxiway. So we wouldn't spray any aircraft behind us, and there was nothing in front of us but an old closed up hangar (probably 50-75 ft in front of us).

But I will concede that you have a good idea about leaving a note for the ground crew and leaving it where it was at, however there was no "after hours" line that we could call for the lineman. Our concern was leaving our airplane out in the middle of these guys ramp, knowing they weren't coming to work until 7:00 the next morning, and what if another jet pulled in the meantime, and we've now created a road block for all concerned.

It's a mute point now I suppose. There was no damage to the engines, paint job, other aircraft, or egos involved.

 

[Cardinal]

I doubt ice 'n snow are very gentle on the props, but who hasn't used gobs of reverse at low speeds to stay on a taxiway on an icy night?

 

[-9Capt]

the reason they roll forward is to be sure that the nose wheel is locked straight before powering back, it is also still a common practice in the Md80 and DC9 if they are certified to do so for their company

Rolling forward has nothing to do with the position of the nosewheel. As previously mentioned, it's to roll off the tires flat spots, which requires less power to back up. I've done hundreds of them in the DC9 & 717.