Step Change in Safety's Helicopter Safety Steering Group
18 March 2011
This special update deals specifically with the recommendations (where relevant to UK helicopter operations) contained in the Transport Safety Board of Canada's recently published report (Aviation Investigation Report A09A0016) into the Cougar Helicopters S92 accident off Newfoundland in March 2009. In order to answer possible questions raised by the report, the following question and answer sheet has been provided.
View the step changes in safety's helicopter safety steering group.
Q1. The report raises the issue of certification for the main gearbox's 30-minute “run-dry” capability, and suggests a change in the way the certification of this capability is approved. What does this mean?
A. The report states that the criteria used for certifying the S92's main gearbox's 30-minute run-dry capability (i.e. the ability to continue to function for 30 minutes or more after a loss of lubricant, or a failure of the lubrication system) may not necessarily represent best practice.
The Transport Safety Board of Canada proposes that certain certification criteria be changed for newly made passenger transport helicopters, and that after a phase-in period, these criteria should be applied to existing certifications where appropriate.
The various certifying authorities (e.g. the U.S Federal Aviation Authority, Transport Canada, and the European Aviation Safety Agency) will now consider the recommendation, and any changes to be made to the certification of the run-dry capability will be announced to the helicopter industry in general.As far as the UK is concerned the Civil Aviation Authority continues to accept the existing S92 certification, but remains in close contact with international authorities.
Q2. Have there been associated interim (technical) recommendations for the S92 whilst the investigation has been ongoing?
A. Yes; there have been a number of Technical Airworthiness Directives and Safety Information Bulletins issued with regards the Newfoundland accident. The first involved replacing the original Titanium studs holding the filter bowl with steel studs. Subsequently, a completely new (two-piece) filter bowl design was introduced which superseded the previous design. All of these modifications have been fully implemented across the S92 fleets operated in the North Sea.
In addition, the Sikorsky Flight Manual has been revised to provide additional guidance to crews on the interpretation of cockpit indications and the actions required by the crew.
Q3. One recommendation is that aircraft do not operate in sea states which exceed the certified approval of the floatation gear to permit safe ditching. How does this affect North Sea operations?
A. Although this recommendation is specifically for aircraft operating under Transport Safety Board of Canada, the principle of operating in a ‘hostile environment', where sea states exceed the certified capability of the emergency floatation gear to provide ditching stability, could be applied to all aircraft in all regions and is therefore being reviewed by the UK offshore aviation sector.
However, it is worth noting that the vast majority of aircraft operating in the North Sea are fitted with floatation gear that is certified to a higher limit than those fitted to the aircraft involved in the Newfoundland tragedy (Sea State 6 - up to 6m waves, rather than Sea State 4 - up to 2.5m waves).
It is also worth noting that the number of days when the sea state (SS) exceeds SS6 within the North Sea is considerably lower than in the waters off Newfoundland. Nevertheless, the recommendation made by the Transport Safety Board of Canada investigation has been taken up by the Oil & Gas UK Aviation Safety Technical Group, who will undertake a review of any implications for North Sea operations and make recommendations to the HSSG.
Q4. The issue of a supplemental breathing system for all passengers was raised in the report – what are the implications for North Sea operations?
A. In the North Sea, all passengers are already issued with and trained to use the type of re-breather systems recommended in the report.
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