1. Main Gearbox Malfunction/Collision with Water Cougar Helicopters Inc. Sikorsky S-92, C-GZCH St. John’s, NL - March 12, 2009 Wendy A. Tadros, Chair Mark Clitsome, Director of Air Investigations Mike Cunningham, Investigator-in-Charge Jean-Marc Ledoux, Regional Manager Quebec

2. Photo of C-GZCH (occurrence aircraft). Source: Mark Stares 2008

3. Wreckage Recovery and Examination

5. A complex equation of 16 causes and contributing factors.

6. TSB Safety Advisories October 2009 Helicopter pilot helmets December 2009 Survival suits December 2009 Automatic oil bypass system March 2010 Emergency flotation systems

9. Flight Path

12. Contributing Factors Ambiguous Emergency Procedure Knowledge of Helicopter System Crew Simulator Training Ditching in a Hostile Environment

13. Photo of C-GZCH (occurrence aircraft). Source: Mark Stares 2008

14. S-92 Occurrence Australia, July 2008 S-92 loses oil from main gearbox. Cockpit warnings, crew reaction very similar to Flight 91 accident. Safe landing 7 minutes later.

15. Galling Damaged titanium studs found. Thread galling from repeated removal/re-installation. Titanium does not withstand wear from metal on metal contact very well. More frequent oil filter changes than expected. Damaged titanium stud from another Cougar Helicopters S-92

16. After Australia S-92 Occurrence Fall 2008 Mandatory enhanced inspection of titanium studs. January 2009 Alert Service Bulletin to replace titanium studs with steel within 1250 flight hours or 1 year. Cougar Helicopters Ordered steel studs. Did not perform enhanced inspections of titanium studs from Fall 2008.

17. Main gearbox must be able to run without oil for at least 30 minutes. To enhance landing opportunities. Sikorsky was confident S-92 could meet this requirement. Helicopter Certification

18. Main gearbox failed after 11 minutes during test. Rule includes clause that test not required if failure shown to be extremely remote. Oil cooler most likely failure route. Bypass valve added. Oil filter bowl and its fasteners not assessed.

19. Four Recommendations 1.All S-92 helicopters to meet a 30-minute run dry 2.The FAA to decide if even 30 minutes is enough time 3.Transport Canada to restrict flights where the helicopter’s flotation system is not up to the task for the sea conditions that day; and 4.Emergency breathing equipment on flights where survival suits are required

20. 16 factors were at play that day.