reverse thrusters

[flx757]

flex757,

Totally off the subject, what kind of guitar is that in your avatar?

That would be a Carvin CT4M .

 

[surfnole]

Air Florida Crash

Here's a link where thrust reversers were improperly used for pushback and it contributed to the accident cause.

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020917X01907&key=1

 

[furloughed]

A pilot told me that the thust reversers at slow speed suckd in a lot of FOD, and was bad for engines?
Is this as great of a concern as extra fuel burn?

FOD is less of a problem with tail mounted engines such as on the DC-9 series airplanes (MD80 and 717s). I don't think I have ever seen a airplane with wing mounted engines do a powerback because of this (FOD).

 

[GravityHater]

The one thing that no one has mentioned is that for any company (135 or 121) to be able to power back, they must be authorized to do so under Ops Spec C065

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?

 

[flx757]

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?

Yes, the information was available to the pilots on board the aircraft in one form or another. When I worked at companies that did powerbacks, it was covered in the Company Ops Manual or Flight Ops Manual, (depending on what that particular company called it), and the pertinent OpsSpec was referenced in that section of the Manual. For companies that did powerbacks, they weren't "rarely used", it was SOP. It was covered thoroughly in training and OE and the airport/gate information was also readily available on board. So your concern was not an issue at all.

For what it's worth, all OpsSpec C065 says is that the company is authorized to use powerplant reversing systems for rearward taxi. How, when and where is further spelled out in the Flight Ops (or similar) Manual. No dispatch interpretation is required unless you are doing some irregular ops or something to that effect.

 

[CrewResearch]

More reverse thrusters

I have to admit that, until I read this thread, I had never heard of using reverse thrusters for "powerback".

But then, I'm here to learn whatever I can about all that you guys do.

So, after I read this thread, I asked a pilot I know (senior captain with a US mainline, currently flying 757/767) if he had ever heard of this, or done it.

He told me that the airline he works for does not "allow" using reverse thrusters for anything except after landing to stop/slow the a/c. However -- he said he once used reverse thrusters to back up the a/c (a B727) enough to turn onto a taxiway, after "running out of room" due to fierce wind blowing the a/c sideways after landing, etc. He said it was the only thing that prevented a runway excursion.

Anyone else have an experience like this? Just curious...

 

[User546]

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.

 

[CrewResearch]

Makes sense...

 

[Weasil]

He is correct, at US Airways Express we are not allowed to use reverse thrust for powerback either.

He told me that the airline he works for does not "allow" using reverse thrusters for anything except after landing to stop/slow the a/c. However -- he said he once used reverse thrusters to back up the a/c (a B727) enough to turn onto a taxiway, after "running out of room" due to fierce wind blowing the a/c sideways after landing, etc. He said it was the only thing that prevented a runway excursion.

Anyone else have an experience like this? Just curious...

A guy I flew with last week told me he parked on an icy ramp that morning and the aircraft started sliding forward even with the parking brake on. The only thing that stopped him from hitting something was some reverse thrust.
By the way Crew Research... they are called Thrust Reversers, not reverse thrusters.
Aside from the cost of fuel and FOD on the ground - the deployment of a thrust reverser costs money (mechanical wear and tear). manufacturers have a good idea how many cycles you get before equipment gets replaced. If every flight used powerback as well as thrust reverse on landing it would halve the life of the reversers. Let's say deploying reverse thrust cost $30/cycle. If you have 100 airplanes pushing back 5 times a day that is $15000/day. That equals $5,475,000/yr in powerback expenses.

 

[bafanguy]

At my former airline, the ops manual prohibited use of reverse to back the airplane unless it was the ONLY means of movement, and then only with special, one-time, FAA approval through an "Operational General Manager". In other words, you couldn't do it without an Act of Congress.


However, policy did allow use of idle reverse to assist the tug during pushback on a clippery ramp after coordination with the ground personnel. I used this a number of times over the years.

 

[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.