xbleed start during push back
 

Is it possible ( with B737) start the engine n°2 with xbleed start during the push back maneuver???
if the tractor is very big and strong, is it still prohibit ???
I couldnt fing any limitation regarding it....if you do paying attention is it legal????:confused::confused:

graziani: I am sure its possible..............but the question you should be asking .....................is it WISE?

You would be unwise to do so, one engine at high power is enough to put a lot of extra load on the tow bar with the potential to break the shear pins in the bar.

The result of this would be the aircraft propelling its self at high assymetric power towards a tractor also at high power going in the opposite direction, who knows which way the sheared tow bar would go !

The chances of one of the ground crew going into the engine are high and it is very likely the tractor driver would be crushed between the loose aircraft and the tractor.

And all this for what ? Saving a few seconds............ As I said a very unwise and unsafe idea.

I know that it is a maneuver where you have to pay attention with risk.....
Im not asking if wise or not ...

But Iwoukld like to know if there is any legal doc regarding this procedure and what boeing says about it ???:hmm:

It is prohibited by all airlines I have worked with.
If you tried it while I was on the headset, the pushback would stop and we would be gone.
You have to advance the throttle when the aircraft is pointing in the wrong direction. There may be loose containers behind that you blow over, and you can easily break the tow bar.
Don't try it.

xbleed start during push back
 

Not to mention and pax boarding or disembarking in the jet blast path getting pebble dashed.as mentioned,far too dangerous, even for the biggest tug, or most experienced driver. Always straight down the taxi way, engine towards blast screen, and tug/tow bar disconnected (maybe chock in front of nose wheel) prior to over idling running engine.i suppose it does depend on airport rules though

On certain airports we used, it was normal SOP to do it during push back. No tow bar in use there and the tractors were rated up to A380 and had no problem at all with tiny aircraft like our 737s, enough blast space behind and no open boarding and deboarding possible anyway, only via protected jet bridges, even on non-terminal positions.

I think if you try this and break a pin or a tug you'll be told the exact document and Boeing's opinion, but will this make you happy? ;)

Why does there need to be a legal doc to prohibit something idiotic? Are you an airman or a drone?

On a 737? Nope
However on the A330 or 777 no problems as you get enough bleed from the running Engine at idle. :ok:

No problem on the Tristar either - it was normal procedure to fire up one engine prior to pushback, then fire up the second once you're rolling backwards.

If the tug is up to it, and the groundcrew briefed then there is no safety problem. Anything in the efflux path means the groundcrew won't give permission to start anyway...

Grazini...

Have a read of this which should answer your question.

xbleed start during push back
 

Cool hé, some people nearly call the OP a moron, other say it's SOP in their company...

@ glum
Of course it's a normal procedure to start the engines during push back but with APU bleed air only. I remember a A321 in FRA which tried a cross bleed start during push back and this resulted in a hugh damage!

About a year ago, there was a 777 that was starting an engine during pushback (using the APU). Unfortunately the crew had neglected to place the throttle to idle before initiating the start - as soon as the engine started it rapidly accelerated to power.

The aircraft rotated into the tug and the (running) engine impacted the tug. From the event report "The pushback tractor driver, during these events, run away from his position in the tractor’s cabin…" :eek:

Miraculously no serious injuries, but considerable damage to both the airplane and the tug. Presumably there was also damage to the tug drivers underwear :sad:

The only person you should be asking this question to is your engineer/technician if pushing. Generally I do not clear for advancement in throttle until I have the tug and towbar linear with the aircraft close to the taxiway/lane line. All aircraft are different, I watched a 777 with 115B's snap a towbar in a tight turn during pushback with one engine running and the other cranking. If it was a 737 or 319 I might not care.

Is it possible to cross bleed start during push back? Sure it's possible. Is it smart? Check your NNPs in your FCOM and you will discover that it's not a smart move to do a cross bleed start during pushback.


Starting both engines with the use of the APU during pushback is not to be confused with a cross bleed start.

Common sense........lost in SOP's
 

glum I am assuming that you misunderstand the B737 terminology, I don't think that you would put one of the wing engines on your Tristar up to 80% N1 during pushback.

Chough

I am endebted to for finding that accident report, I did not know of the inccident but it seems to have panned out much as I predicted in post #3 but fortunately without injury to any one, but clearly the tractor driver was of the opinion that it was wise to leave the area with some haste!

Graziani

As English is clearly not your first language I will tell you that when an Englishman says that something is unwise it is a polite way of saying that it is a stupid idea. My concern is that you are more interested in if there is an SOP for this or some legislation to prohibit the practice rather than considering the physical aspects of the way the forces that the aircraft and tractor are producing will be interacting, if you had taken the time to think about this you would have been unlikely to ask the question in the first place.

On a general note I have noticed that some of the newer people in the industry have become SOP drones who are totaly convinced that if they stay on SOP and within all the rules they will be safe, they are very keen to point even the slightest non compliance with SOP without understanding the reason. These people seem to know every thing and understand nothing.

really not a good idea...

These words are worth being printed in every SOP as an afterword! Preferably in bold type :)