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ATA 09 Towing & Taxing

ATA 09

Towing and Taxing.

For those who donít now the difference between these two, towing is done with the help of a tow truck and tow bar or with a nose lifter. Taxing the plane uses his engine to produce trust and gain speed/movement. But this you already knew I guess. Any way.

There are several ways to tow an airplane. You can either tow at the nose gear or at the main gear. Depending on which surface the plain is on. If its on hard ground like tarmac or concrete you can tow at the nose gear. In case the plane is positioned in mud or other soft under ground you can only tow at the main gears NOT at the nose gear. Because the drag the plane will create during towing in such under ground will be higher then the strength of the nose gear construction. If done so, the nose gear will be damage severely or it can even result in the nose gear drag link collapsing, the plane will fall on his nose, causing damage to the plane and possible kill some one in the process.
So if nobody is willing to listen to you, get far enough away from the complete plane!!!

The towing on hard surface.

Can be done with two possible trucks:
 
1.) Tow truck and tow bar.

2.) Nose lifting truck.

This last mentioned I was able/allowed to drive. This is also the easiest one in use. Using a tow bar creates two pivot point while the use of a nose lifting truck only uses one, the nose gear itself. Also for safety reasons the nose lifter is better.

Whatís a nose lifting truck?

Itís a truck in the shape of a big U. Its equipped with a strong Diesel engine driving a large hydraulic pump. This pump drives in turn the left and right hydraulic motors mounted strayed on each wheel. So in fact the truck gets its drive hydraulically, and with good reason. If it would be done with mechanical linkage it would make the nose lifter to big and it would still be possible to lose one or both drive linkages by breaking or other malfunction. Possibly causing damage to the airplane by particles of the truck. And hydraulic systems are much stronger and compact. In case of malfunction, letís say one of the lines break the only thing thatís going to happen is a lot of fluid loss, no damage to the plane, just some rags to clean it all up and away the plane goes!! So again you see that on every job your dealing with airplanes safety is always considered very important!!!

Push truck with Tow bar.

This is nothing more then a large powerful truck equipped with a strong Diesel engine. Itís connected with the plane nose gear by a tow bar. A tow bar has on one side a specific hook-up system thatís depending on which type of airplane you want to push or tow. Itís got a hydraulic system to be able to regulate the height of the tow bar upon connection on the nose gear. This system consist on a hydraulic actuator connected to the wheel installation thatís installed to transport the tow bar between two push-backs. 

In case to much force is put on the tow bar one or both shear bolds will break to prevent any damage to the airplane nose gear by the excessive force. For example, if the guy doing the start-up of the plane forgets to lock the steering out with a steering pin. Then from the moment the engines start to turn, the hydraulic pump on the engine will supply on most planes hydraulic pressure to the steering. But the steering is still connected to the tow bar and truck, resulting in two opposite forces that are both very strong. And so something has to break. In that case we all prefer the tow bar, don't you?

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