"Do not let the aircraft stop when in a turn"?

[nicky9499]

I have read this in two manuals now, CLS' A340 and 742, it states that the pilot should not allow the plane to stop when turning during taxi. Is this true in the real world and if so, why? Just curious.

[InsyleM]

Its true in real world for some aircraft. I would imagine the A340 is one of them.

Turning puts alot of twisting force onthe gear. Espessly gear that has 2 axles, as there is no steering for the indivual axle.
This causes the front two wheels to be pushed one direction while the back two are pushed the other direction. Moving the aircraft forward after a turn x amount of feet (C-5 is was 50) releieves this stress. Stopping in a turn keeps the gear in this stressed position.

[Propane]

Add to that the simple observation that getting an aircraft to roll again with a nose wheel position other than centered takes a lot more power.

[nicky9499]

Hi guys, thanks for the insight.

So what they actually mean is don't park the aircraft when it's turned? I understand the whole stress on the wheels thing. Heck, I even make it a habit to "pull straight forward" a couple inches when parking my car. But it is okay to stop briefly when turning during taxi, right? Perhaps ATC instruction or something.

[InsyleM]

I would imagine that in an emergancy you could. Like if theres about to be a collision. But like the OP said, it would probably take alot extra power to get it rolling again. If I remember right I think we had to tow C-141s forward 1 complete revolution of the wheels. But I think the stresses are greater when its stoped in a turn then when its still rolling in the turn. While rolling it can let the tires slide a little sideways to help aleviate some of the stress.

[tommchowat]

If you need to stop, then you need to stop. What about a curved taxiway leading to a runway holding point with a queue of traffic on it? Wouldn't take too much common sense to centre the nosewheel just before you stop.

[nicky9499]

Thanks for all the info guys, I learned something new today.

[angels355]

Regarding other concerns on the ground, on big planes such as the 747 you can only taxi a limited distance before you have to bring it back to the service center to have the tires examined. That was for the 747-200, I can't remember the distance but it was not that far. Perhaps tires have improved since then and the distance you can taxi has increased, not sure. Got a 747-400 manual but haven't had time to read it. The 747 has a few other peculiarities that are "counter intuitive", in other words, while it seems easy it's harder than it looks. Company policy at one airline says that for 747's, on the ground, the entire crew (cockpit crew, and flight attendants in passenger cabin) needs to be looking out the windows to warn of obstructions. Take for example the A380 that was taxiing and hit the tail of a small airliner, the cockpit crew is not perfect.