Examination of wreckage from the March 12 crash of a Cougar Helicopters S-92 prompted manufacturer Sikorsky to recommend the grounding of all S-92s last Friday unless their titanium main gearbox oil bowl mounting studs had already been replaced with steel ones. Investigators for Canada’s Transportation Safety Board (TSB) found a broken stud on Cougar’s S-92 that crashed into the Atlantic Ocean off Newfoundland minutes after the pilot reported “zero” MGB oil pressure. The two-man flight crew and 15 of the 16 oil rig workers aboard were killed. TSB investigators suspect the broken stud was a “contributing factor” in the crash and last week recommended that the FAA issue an emergency Airworthiness Directive grounding all S-92s that had not had the part replaced. The FAA did so yesterday. On January 28, Sikorsky issued an alert service bulletin recommending that the part be replaced within the lesser of one year or 1,250 hours. Yesterday, Sikorsky reported that 50 of the 91 S-92s in service already had been fitted with the new studs and that work was expected to be completed on most of the remainder of the fleet by week’s end.