Safety checks reveal 'faults' with North Sea helicopters
Inspectors uncover potential issues with three Babcock S92s and another owned by CHC.
Safety checks have uncovered potential faults in at least four North Sea helicopters, STV News has learned.
Dozens of S92s were grounded for inspections in Aberdeen this week after a chopper spun out of control trying to land on an oil platform.
The decision caused widespread disruption to North Sea travel and paralysed the coastguard's search and rescue fleet.
It has now emerged that inspections revealed possible issues with three of 11 offshore helicopters owned by Babcock and one of 14 owned by CHC.
The Air Accidents Investigation Branch (AAIB) believes the incident aboard the West Franklin platform occurred after a bearing failed in the rotor of the S92 and could have happened at any time.
The helicopter spun 187 degrees before its pilot forced it down and its 11 crew and passengers disembarked safely.
'These findings do not constitute failure of the bearing and are being returned to Sikorsky for further evaluation.'Sikorsky spokeswoman
A spokeswoman for S92 manufacturer Sikorsky said: "Physical inspections of the tail rotor pitch change shaft bearing are well underway with over 250 aircraft inspected.
"Sikorsky has been reviewing health and usage monitoring systems from those aircraft as well.
"A small number of parts are being returned to Sikorsky for additional evaluation. These findings do not constitute failure of the bearing and are being returned to Sikorsky for further evaluation.
"Sikorsky continues to work closely with our supply chain on replacement parts and is coordinating those activities with our customers."
S92s and Super Pumas, which are already grounded following a fatal helicopter crash last year, are responsible for the vast majority of flights offshore.
Some S92s which were already in the air when Sikorsky issued its alert at 8am on Tuesday were forced to turn around and return to base.
A spokesman for Babcock - formerly Bond - said: "Babcock has completed the required inspections on the whole of its S92 fleet.
"As a result of the inspection findings, three bearings have been returned to Sikorsky for evaluation.
"All aircraft are subject to a full testing programme ahead of their return to service."
No Bristow helicopters were affected, according to the firm.
The American Federal Aviation Administration (FAA) issued a warning to helicopter operators just over a month before the incident aboard West Franklin after an S92 went out of control in the US.
Preliminary enquiries by the FAA determined that the likely cause was also fault in the helicopter's rotor.