Reverse Thrust Whilst Taxying
 

Saw one of those rather elegant Gulfstream exec jets taxi out the other day and he appeared to be using reverse thrust to slow himself down on his way to the runway. Is this normal practice with this sort of aircraft or was he just trying to save his brake pads? Surely fuel costs and engine wear would make this an expensive way of speed control? Any ideas?

I'm not a Gulfstream guy but I have seen this too, shouldn't be much of a FOD risk from that height.:confused:

He was probably already at idle thrust when selecting reversers, so there would be no additional/extra fuel flow or engine wear.


Edited to ad a question....

I fly a jet a/c with tail mounted engines. We (well, actually the captain) often select one reverser only during taxi to save wear on the brakes. The reason we select one reverser only is that if we were to pull both reversers that would also deploy the lift dumpers, which of course we're not really interested in during taxi.

So far so good....

Single engine taxi is, according our SOPs, not allowed (although that would save a lot of fuel...). I asked our technical pilot why, and his explanation is that single engine taxi will create a yaw moment which will adversely affect our nose wheel tire or perhaps even the entire nose gear. I'm not sure if this is a fact supplied from the manufacturer or if it's just out technical pilot thinking outside the box...

So here's the question.... Wouldn't taxi with one engine on idle thrust and the other reverse-idle create an even larger yaw moment than taxi with one engine at idle/low-thrust and the other shut??

Have noticed the same thing, usually with only one engine in reverse. Could a G driver clue us in?

It is a common practice on Gulfstreams, MD80/90s, Boeing 727s, and other aircraft where FOD is not an issue. This technique helps to prevent over usage of brakes during long taxi routes which can result in overheated brakes. This technique is not designed to repace the use of brakes to bring the aircraft to a stop and power settings above idle thrust are never used.

On the 737-200 at LGW, we used to taxi out on 1 and start up the remaining in the hold before take-off. I don't recall unbalanced thrust being a factor at all. On aeroplanes with high idle thrust and possibly light weight, it is very useful for not stamping on the brakes all the time. You don't want hot brakes before you even start your take-off roll!

we did use center engine idle reverse all the time on the 727
on the 757 with the RR engines the idle is too high and the plane speeds up all the time (we fly a lot at low weight).
We are not allowed to taxi out on one engine (engine warming takes 5 min when cold) but we can do it when taxiing in ,i never notice any problems ,but its important to think what turns you have to make at low speed onto the stand to deside which engine you shut down.


Neil

Used to often see the good old L1011 taxying around with No2 in reverse.

Lot's of planes have a lot of excess thrust at ground idle. Idle reverse helps mitigate the excess thrust, keeps the speed under control and reduce brake usage. If allowed by the book, a sensible option.

Did that a lot on the 727, kept #2 on reverse to stop a light aircraft from running away..

As well on the CRJ this a often used proc. The reason is very simple - saving costs on brakes. You just use reverse on idle and of course you don`t cycle the reverser. Good examples are Stuttgart Rwy 25 or Paris CDG Rwy 26(long downhill section). Happy landings...

Have done it on large aeroplanes with low engines.

The manufacturer says you can use reverse idle down to taxi speed, if the alternative is brakes too hot to take off with, I will try reverse idle for sure.

Taxiing in, let the engine run it's cool down cycle then shut one down - make sure it's not the one that powers the hydraulics :{

I'm using reverse during taxi on a regular base on the 737 (classic and NG)-saving brakes...
Both reversers at idle thrust,it's allowed by Boeing.Just keep an eye on the taxiway,to be free of anything that can be dangerous to the plane.
Single engine taxi it's not recommended due to the requirement for proper warm-up of the engines prior to take-off max thrust.

In theory won't taxiing with only one of twin tail mounted engines have less of a yawing effect that one of twin wing mounted engines because the engines are located closer to the "centreline" of the aircraft?

We, and many other operators, used to use reverse thrust on 727's for reversing out of the gate back in the 80's. Procedure was to move forward a few feet and then select reverse thrust and reverse out including turns, to position for taxi.

Our SOP's do not allow that procedure with 737's. We do single engine taxi, on the jurrassics (200) if the T/O weight is below 100000 lbs and on the classics below 110000lbs. Remaining engine must be started so as to allow it to run for 2 minutes at idle before T/O

fluf