3 Suspension bar
My profession is mechanic, more then 30 years with the steel technique, but I can not conclude the cause of the accident on Turøy.
I hope AIBN.no find the cause. I will explain elements called : Problem number 1
A
Fracture surface on the bearingarm tell me that the steel structures is hardened, and the steel toughness is small.
Steel structure change during welding, and the break may have occurred as a result. I do not know if annealing is done.
Ref : Weld is somtime stronger, and the ship Sleipner broke in 2, near the weldplace
It is best to make all suspension bar in one piece. Another factor is whether all suspension bar are vibration and bendtestet
by the manufacturer. Normal procedure by roller bearing assembly is to heat the bearingarm in oil and then assemble the bearing
Normal clearance is some hundredths mm clearance. When bearingarm has cooled then the roller bearing sits completely fixed.
B-C
Probably when the bolt C is mounted into B it will be few hundredths mm clearance, and the result becomes slack. Is there any
slack - vibration damage by E. I guess all the parts are not heated before bolt C is fitted into B. Before the put the bolt to travel block on a drilling rig
the boltis being frozen before assembly. Injuries outside B ?
If shaft C is loose and rotates - vibrates will D change shape. Shown in the picture F.
The locking string has changed shape. This can wriggle out of the shaft or be cut. A missing / broken shaft / part / may result in helicopter crash.
There are many other and better technical solutions then the pictures shown.
AIBN.no present images shown 3 suspension bar and 5 bolts