Wheel Bearing Failure 2

[heavenarmy]

For aircraft with single wheel, are there any contingencies or mitigating actions to guard against wheel bearing failure or tire burst on one side?

On a separate note, there have been reports of aircraft wheels dropping off during landing or take-off. Does anyone know what are the likely causes of these failures?

 

[flash3780]

Sounds like a maintenance issue. This Colgan Air Q400 looks (to me) like the maintenance crew forgot to torque the bolt and there was no secondary retention.

http://www.talkairline.com/aviation-videos-pictures/videos/419/

 

[ERAU82]

The main cause of wheel bearing failure is loss of torque on the axle nut due to improper torquing procedures. As the nut is tightened, the wheel assembly is rotated by another maintenance technician. This seats the bearings properly. The other important aspect is to follow the torquing procedure per the manual or workcard - it is usually to over-torque the axle nut to a designated value, then loosen the axle nut and while still rotating the wheel assembly torque to the proper value.

The cone bearings are designed to be loaded axially. The loss of load on the bearing causes overheating, loss of lubricant and the resulting friction will cause the temperature to rise to the point of melting the rollers causing a catastrophic failure. This also will damage the axle, scoring the bearing journal and causing excessive heat that may result in cadmium diffusion of the axle (which scraps the axle).

If the retention (anti-rotation) device is not properly installed, then the axle nut will either tighten or loosen depending which way the wheel assembly rotates in relation to the RH thread of the axle nut. In both cases, the bearings will fail. A little forensic work can determine if the retention device was installed - look where the device should be and if not installed, the area would have fresh lubricant or dirt present. If it was installed, then the area should be 'cleaner' than the surrounding area.

I've had bearing failures result in the wheel assembly departing the aicraft on take-off. Luckily, these were on nose landing gear with 2 wheel assemblies.

Sorry for the long reply. Hope this helps.

 

[IRstuff]

A gigantic portion of equipment failures are either poor or improper maintenance. DC-10 engine breaking off attributed to improper engine lifting at American Airlines.

TTFN

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[heavenarmy]

Thanks for the explanation.