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Chronology of events: offshore helicopter Cougar Flight 491

 

This draft chronology of events has been compiled from information provided by the Transportation Safety Board of Canada.

 

Times are in Universal Time Co-ordinated , or UTC, (roughly equivalent to Greenwich Mean Time).

 

11:48:07 Cougar Flight CHI91 departs St. John's.

 

12:05:52 CHI91 advises Gander Area Control Centre (ACC) that they have levelled off at 9,000 feet and that their estimated time of arrival at the Hibernia platform is 13:10. Speed is 110 knots.

 

12:15:05 Rapid loss of main gearbox oil pressure occurs. No abnormal indications of any kind recorded on flight data recorder prior to this event.

 

12:15:19 CHI91 begins a right turn.

 

12:15:24 Main gearbox oil pressure decreases to approximately five psi.

 

12:15:27 CHI91 issues mayday call to Gander ACC and begins descent from 9,000 feet. They are 53 nautical miles from St. John's.

 

12:15:32 CHI91 advises Gander ACC that they have main gearbox oil pressure problems and requests immediate clearance to return to St. John's.

 

12:15:43 CHI91 heads back to the coast. Their heading is 290 degrees and their speed is 120 knots.

 

12:17:04 Main gearbox oil pressure reaches 0 psi.

 

12:17:25 CHI91 advises Gander ACC that they are heading for nearest land. Their heading is 292 degrees and their speed is 122 knots.

 

12:17:42 CHI advises Gander ACC that they have lost all main gearbox oil pressure. CHI91 is descending through an altitude of 5,740 feet.

 

12:18:25 Gander ACC advises CHI91 that they are 42 miles from Cape Spear.

 

12:19:10 Gander ACC advises CHI91 that search and rescue has been notified.

 

12:19:18 CHI91 advises Gander ACC that Cougar dispatch has been advised and that another helicopter is being readied.

 

12:22:20 CHI91 levels off at approximately 800 feet. Their heading is 292 degrees and their speed is 133 knots.

 

12:24:44 A power interruption to the Flight Data Recorder/Cockpit Voice Recorder occurs.

 

12:25:36 CHI91 advises Gander ACC that they are preparing to ditch.

 

12:25:52 St. John's radar records CHI91 at 800 feet. CHI91 subsequently descends to 300 feet in approximately 29 seconds which equates to an approximate rate of descent of 1,000 feet per minute.

 

12:26:26 St. John's radar records the last radar return of CHI91 at 300 feet.

 

12:26 Gander ACC advises search and rescue that CHI91 has ditched. Cougar dispatch confirms the ditching with search and rescue, and advises that they will launch Cougar 61 as a rescue helicopter.

 

12:42 A Provincial Airlines patrol aircraft arrives at crash site and observes two people in orange immersion suits in the water.

 

13:07 Cougar rescue helicopter departs St. John's.

 

13:25 Cougar rescue helicopter arrives at crash site and spots two people (one of whom is later confirmed dead), two rafts and helicopter debris.

 

13:33 Cougar rescue helicopter lowers a rescue person toward the people in the water.

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Not wanting to disparage the significance of this tragedy, but I have to wonder why titanium studs were used when steel studs, as required now by Sikorsky, would do the job?

 

Of course the other question is why did a modern helicopter, certified to all of the latest standards, only take 11 minutes to crash following loss of transmission oil pressure when the certification requirements say it must demonstrate 30 minutes flight at cruise power upon loss of transmission oil pressure???

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Not wanting to disparage the significance of this tragedy, but I have to wonder why titanium studs were used when steel studs, as required now by Sikorsky, would do the job?

 

Of course the other question is why did a modern helicopter, certified to all of the latest standards, only take 11 minutes to crash following loss of transmission oil pressure when the certification requirements say it must demonstrate 30 minutes flight at cruise power upon loss of transmission oil pressure???

 

Saving weight with Titanium studs? Certainly won't save money. What other reason could there be? Seems like an odd choice of material for sure.

 

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