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.