http://www.onderzoeksraad.nl/publicaties/ovv/intermediate_report_bristow.pdf29 March 2007
Intermediate report
During an evacuation mission of an oilrig on the North Sea with a Eurocopter
AS 332L2 search and rescue helicopter on 21 November 2006, on the way back to the
mainland, at 3,000 feet the N1 RPM of engine #1 fluctuated while its temperature
rose. At the same time the temperature of engine #2 decreased. The crew tried to
identify which engine had problems but did not succeed. The decision was made to
descend to 1,000 feet. During descent cyclic control problems developed. The control
problems increased rapidly, whereupon the crew decided to ditch the helicopter into
the North Sea. All thirteen passengers and four crew members evacuated the aircraft
safely. The helicopter was equipped with two automatic inflatable life rafts. These life
rafts were not inflated. A small life raft (‘air droppable’) that was carried in the cabin
was inflated by the cabin crew. Two occupants succeeded in climbing in the raft, all
others remained in the water. All occupants were wearing survival suits and were
rescued within 1 hour 15 minutes.
During the ongoing investigation, the deployment of the life raft stowed in the lefthand
sponson was tested. The test revealed that the life raft could not be deployed by
means of the normal activating mechanisms. Detailed investigation showed
deficiencies in the design and maintenance procedures of the activating mechanism.
Eurocopter, Bristow, the French BEA, the AAIB UK and the Dutch CAA were notified.
Eurocopter responded by announcing the issue of a Service Bulletin for improvement
and stated that the AS 332L2 is the only type that is equipped with this life raft
activating mechanism. The Safety Board did not extend its investigation to other
helicopter types. The Service Bulletin has not yet been published.
Based on these findings the Dutch Safety Board asks the certifying authority for the
Eurocopter products, the European Aviation Safety Agency, to take the following
actions in order that:
· Operators check the proper functioning of the life raft activating mechanism
on the AS 332L2 Eurocopter helicopters equipped with sponson mounted life
rafts within two months after publication of this message.
· Eurocopter improves the design of the sponson mounted life raft activating
systems to assure proper deployment.
· Eurocopter improves the maintenance procedures of the sponson mounted life
raft activating systems as needed.
