[Bell Historians] Steel kingpost frame

[Bickerton, Roderic K (SELEX) (UK)]

Detail of that bolt failure.
The bolts had rusted through inside the baring casting fixing holes.
The fault would not have been visible with or without paint.
The bolt heads were not heavily rusted under the paint.
The cause.
The baring castings are slotted.
The bolt head washer did not fully cover the slot.
Water ran into the slot and could not escape
The bolt lay in a puddle and continuously and invisibly rusted.

Better design would have placed round holes in the baring castings and
slotted the frame heads, so that, water could not get in and even it
still did, it could drain out.

I would recommend checking for the same fault on any ring with this
pattern of baring housing especially if the baring is near a wind wood
tower opening or in an area where sea spray, an exposed position or
industrial pollution is likely to speed up corrosion.

It is a nasty potentially dangerous and invisible fault. The only way to
find it is to take out the bolt for examination.
In this case the bolt had not just necked, but 1/2 inch of steel had
completely rusted through!




SELEX Sensors and Airborne Systems Limited
Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL
A company registered in England & Wales.  Company no. 02426132
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