So in a sense, you don't want the nose wheel to turn past the the steering system limits with the steering system connected to prevent damage.

 

Right, but just to be clear for those who don't already know, that's the physical limitation of the linkages.  Bypassing the gear by depressurizing, pinning it out, switching the steering off and so on will not remove these physical limitations.  Bypassing, pinning or turning the nose wheel steering system only removes pressure from the nose wheel, allowing it to turn more easily.

 

The only way to side step the physical limits is to disconnect the torque (scissor) links, as Rob mentioned, if it's possible on the aircraft.

Actually thinking back, I can only remember starting engines once or twice during push back. We had a procedure for it but never used it. If in a hurry, we would start all 3 at the same time after the push. It was actually rare for use to pull into a gate also.

we would start all 3 at the same time after the push.

 

All 3???

 

EDIT:

Derp.  I associate you with the Gulfstream, not the DC-10.  Just remembered you flew the -10, too.  So yes, 3.

All 3???

 

EDIT:

Derp.  I associate you with the Gulfstream, not the DC-10.  Just remembered you flew the -10, too.  So yes, 3.

I have all ways wondered why this feature wasn't in the Gulfstreams. One cool feature is during air start of an engine, the system will automatically select the APU(if running) or windmilling for a starting source based on indicated airspeed. If there is a rapid temp decrease rear of the fan section(assumes water ingestion) or a decrease in RPM in relation to throttle position, engines enters auto relight mode and turns on ignition. If an engine flames out and shut downs, chances are that you will never get it started.

 

I'm confused by all the replies!

 

Some years ago I was boarding a 737-500 at my local airport and the identical aircraft at the next gate was being pushed back. I could see quite clearly that the push truck's mechanism had lifted the nosewheels clear of the ground by a couple of inches. So I assumed that the pin was to lock the nosewheel in the straight ahead position as you wouldn't want both the nosewheel and the trucks articulation working at the same time as this would make it very difficult to control.

 

Has this changed? Is the nosewheel not jacked up anymore?

 

Iain Smith

 

 

 

 

Hi

 

its exactly the same principle for the lift type pushback truck as the towbar regarding the pin. the lift type truck does not have any form of articulation mechanism at all it ridgidly holds the nose wheel in a fixed position (centered to the truck) gripping the wheel with rams.and the wheels remains locked in this position relative to the truck as its lifted and turn with the truck as the truck turns hense the need for the pin to disconnect the pressure so there is no conflict. jack up trucks are very common and appear to be increasing in use from what I have seen.

 

 

 

cheers

 

 

 

kav

  

 

 

 

Hi

 

its exactly the same principle for the lift type pushback truck as the towbar regarding the pin. the lift type truck does not have any form of articulation mechanism at all it ridgidly holds the nose wheel in a fixed position (centered to the truck) gripping the wheel with rams.and the wheels remains locked in this position relative to the truck as its lifted and turn with the truck as the truck turns hense the need for the pin to disconnect the pressure so there is no conflict. jack up trucks are very common and appear to be increasing in use from what I have seen.

 

 

 

cheers

 

 

 

kav

 

Thanks kav, that now makes it clear. I was confused as to the exact purpose of the pin.

 

Iain Smith