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On 12 March 2009, Cougar Helicopters Flight 91 suffers an oil leak in the main gearbox while transporting oil rig workers from St. John's, Newfoundland. The helicopter ditches in the Atlantic Ocean during an attempt to return to land, killing all but one of the 18 people on board.
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00:00off the coast of newfoundland
00:14a helicopter crashes into the ocean when you see a tragedy like this it makes many many people
00:24across the country understand the sorrow 17 people are dead remarkably one man survives look at it
00:35somehow he gets out in a helicopter that is sinking past 30 feet that was a long descent
00:43eventually my arms broke the surface it's very important to analyze what affected their ability
00:50to exit the aircraft what investigators uncover has a critical impact on the safety of every
00:55helicopter flying over water that man is lucky to be alive
01:20cougar flight 91 prepares for liftoff this is a commuter run from st john's newfoundland
01:33to offshore platforms in the hibernia oil fields
01:38captain matthew davis is at the controls
01:42in a helicopter unlike an airplane the captain sits on the starboard or right hand side
01:48next stop sea roads first officer tim lanouette is in the left seat
01:56a veteran navy helicopter pilot he's a newcomer to civilian aviation
02:02ground cougar 91 request takeoff
02:05cougar 91 depart to the south then on course clear for takeoff
02:10the helicopter they're flying is a sikorsky s92
02:19it's a large aircraft with room for 17 passengers and their gear
02:25the sikorsky s92 is kind of designed for this mission you can look at the s92 is kind of emerging
02:31of their best ideas from the u.s army's black hawk helicopter
02:35the hibernia oil fields are 170 miles from st john's
02:42it would take 15 hours to get there by boat autopilot engaged
02:48autopilot engaged copy by helicopter it's only a 90 minute flight so for workers on oil rigs it's the
02:56primary mode of transportation we only have two for the sea roads
03:04affirmative and 14 for hibernian let's lighten the load early alpha routing copy
03:11gander cougar 91 uh taking a look at the ops plan here uh we would like to amend our flight plan we
03:18would like to go alpha routing hibernia first then c rose a minor change in plan cougar 91 will travel to
03:28the hibernia rig and then proceed to the c rose platform okay cougar 91 is cleared to hibernia via the amended route
03:39the flight is almost full the 16 passengers are service workers the cooks and cleaners of the offshore world
03:52robert decker is a weather observer for rigs in the north atlantic
03:57he's made this flight 50 times over the past three years because there are so many constraints on the
04:04amount of space and the amount of weight that a helicopter can carry the amenities in the
04:10helicopter are just stripped down to the bone so you're not going to find any of the amenities that
04:14you would find in an airbus or a boeing boiling in here
04:25high visibility survival suits are mandatory on all helicopter flights over the open sea
04:30unlike an airplane if you have to ditch in the water for any reason the aircraft will not float
04:39an airplane will float for you know anywhere from five minutes to many hours the helicopter will simply
04:45sink like a rock 28 minutes into the flight cougar 91 has leveled off at the standard cruising altitude
04:549 000 feet 9 000 feet copy
05:00three weeks on three weeks off
05:06life on a rig i don't know what's worse
05:09three weeks off i'd get bored gearbox pressure gearbox pressure mgb oil pressure
05:18oil is the lifeblood of a helicopter a problem with the oil pressure can be catastrophic
05:23emergency checklist while first officer lanouette looks for the checklist
05:32autopilot off captain davis disengages the autopilot so he has complete control of the aircraft
05:40then he does what all captains hope they will never have to do gander center cougar 91 mayday
05:46go ahead sir we have a main gearbox oil pressure problem request immediate clearance back to take
05:52off cougar 91 roger you can make a right turn heading 300 the controller contacts the search and rescue
06:02headquarters in halifax halifax gander center we have a mayday call from a sikorsky s92 currently on return
06:10to st john's main gearbox problem flight 91 is 54 miles from land it will take them 30 minutes to reach shore
06:22captain davis alerts cougar helicopter's dispatch center in st john's
06:31dispatch cougar 91 we're coming back to st john's cougar 91 dispatch roger keep us advised
06:40i'm taking her down to the water roger checklist yeah i'm still trying to find it it might be at the back
06:48of the book main gearbox failure we should be getting smells vibrations i don't smell anything what about the back
07:03nothing nobody's doing anything in the cabin
07:08cougar 91 is descending to just under 1 000 feet the helicopter is now 52 miles from st john's
07:16gander center for cougar 91 which runway would you like me to set you up for i'm going for the
07:24nearest piece of terra firma i can get to whatever i see first if it's cape spear or a parking lot
07:29okay i got the checklist mgb pressure below 35 psi the pressure gauge indicates that the main gearbox
07:38oil pressure is well below the normal range of 45 to 70 psi confirmed mgb oil temperature greater than 130
07:48degrees but the reading on the temperature gauge is not what it would be if there was a loss of oil
07:54pressure the temperature looks normal problem could be with the sensor
07:58and if you have the time i'll take the souls on board and fuel remaining okay 2992 we have uh
08:11about three hours of fuel on board and 18 persons on board
08:15this is the captain we've had a major technical problem and at this time i'd ask for everyone to
08:25prepare your survival suits we are heading for the closest land
08:37cougar 91 dispatch cougar 91
08:40rescue is asking if ditching is imminent probable or possible
08:47dispatch 91 ditching is possible if possible can you update our senior pilot on the situation
08:53dispatch i think we have an oil pump problem or an oil pressure sensor problem matt can you describe
08:59the symptoms the gearbox oil temperature is still normal i don't think we've lost all the oil in the
09:05system i'm on the system i'm on a heading for closest landfall if this goes south on us
09:10cougar 91 is still 35 miles from the nearest land but now
09:18oh hell dispatch we're ditching ditching airspeed 122 man
09:23i think it just kicked on me okay nose up nose up
09:40all right we're turning call it in we're getting prepared to uh ditch uh ditching
09:46ditching ditching ditching ditching 500 feet you got this get it pointed downwind
10:04race race race race race
10:16the passengers and crew of cougar 91 are now trapped inside a sinking helicopter
10:36one of the most advanced helicopters in the world has dropped out of the sky into the icy north atlantic
10:42off the coast of newfoundland when you see a tragedy like this it makes many many people across
10:47the country uh understand the risks and understand the sorrow 17 people are dead there is only one survivor
10:58robert decker a young offshore oil worker is rushed to hospital with life-threatening injuries
11:04the close-knit offshore oil community is shattered and looking for answers
11:13it's hard you know to believe that it happened to somebody winning your community
11:21this was an international accident there were about 80 sikorsky s92s operating worldwide
11:27and they were operating in every extreme environment you can imagine we really needed
11:34to drill down and figure out what had happened and why it had happened
11:39the answers lie 554 feet beneath the surface of the atlantic ocean
11:46within hours of the crash canada's transportation safety board assembles a team to recover the wrecked
11:53helicopter and discover the cause of the crash mike cunningham will lead the investigation we were
12:04looking at a major accident and it was going to require a significant response from the tsb
12:11the transportation safety board is provided with the atlantic osprey a vessel designed to service offshore
12:17oil rigs alan chalk will lead the recovery effort it's one of the best pieces of equipment in this area
12:27when it comes to recovery it's very well equipped
12:34using the last known waypoints for cougar 91 the ship locates the wreckage within hours
12:41our number one priority was to recover the victims and then the priority became the multi-purpose flight
12:47recorder and the remainder of the wreckage remotely operated vehicles or rovs are deployed to recover the
12:57victims and retrieve the wreckage from the ocean floor
13:05yeah this will do the tsb sets up operations in a hangar at st john's international airport
13:12yeah tell them all the wreckage comes in here
13:26there was no indication of any problems until the mayday came in right that's what we heard as well
13:32while cunningham waits for the wreckage to be recovered he interviews the air traffic controller who last had
13:38contact with the doomed helicopter we talked to the air traffic controllers to find out how things went on
13:45their end we look at their comm tapes their radar tapes mayday came in at 0945. gander center cougar 91
13:55mayday cougar 91 go ahead sir we have a main gearbox oil pressure problem cunningham gets his first clue
14:03he said that they had lost all main gearbox oil pressure so this was important information for us
14:13the main gearbox uses power from the engines to spin the main and tail rotors
14:19like the transmission in a car the gearbox requires a constant supply of oil to keep moving parts lubricated
14:26the main gearbox in a helicopter is a very critical piece of equipment the failure of the gearbox would
14:36mean a loss of lifting power from the main rotor the loss of directional control to the tail rotor
14:45cunningham needs to find out what caused the oil pressure warning the crew reported
14:49could there have been an oil leak in the main gearbox request the immediate clearance back to takeoff
14:57so the captain requested clearance back to saint john's and that's 54 nautical miles how long would
15:02that take to fly 30 minutes but uh cougar 91 went down in um 11 minutes the fact that cougar 91 went down
15:14so quickly supports cunningham's hunch that there was an oil leak in the main gearbox but it doesn't
15:20explain why the pilots thought they could still reach land so something convinced him that he can make it
15:28back
15:34looking for answers cunningham asks the senior pilot at cougar helicopters if anything stood out from his
15:40radio exchange with the crew anything at all you could tell me would be helpful there's one thing
15:47that bugs me the oil temperature if the oil pressure inside the gearbox is falling and the oil is leaking
15:57out the temperature would begin to rise because now the gears are grinding against each other and
16:01generating a lot of heat he said the oil temperature was normal the gearbox oil temperature is still normal
16:09i don't think we've lost all the oil in the system he thought he still had oil
16:17the crew thought they could make it back to land because the oil temperature read normal
16:22so was the oil pressure warning a false alarm when the crew mentioned the oil temperature and it was
16:30indicating normally uh this told us that we needed to make sure that what they were seeing was in fact
16:37accurate to what was going on with the helicopter
16:44only the wreckage can provide the answers
16:49five days of calm seas make the helicopters quick recovery from the ocean floor possible
16:57over by the cabin floor
16:58the team finally gets a first look at the wreckage what can it reveal about the deadly crash
17:08when you look at an aircraft that strikes land you have a wreckage trail you have ground scars that
17:13can tell you certain things the water gives up very little there's nothing left to look at it's just
17:19the surface of the water so you have to focus on the fuselage damn so it was upright when it hit pancake
17:31dropped like a rock
17:35my initial impression of the helicopter was that it struck the water at a significant vertical rate when
17:41an object hits water water is non-compressible it'll cause a little bit of a different kind of damage
17:47signature than what would be as if it hit the land it's hard to believe anyone survived
18:01investigator alan chalk's recovery of cougar 91 provides a big break in the investigation
18:08there you go what do we got here voice recorder transcript and audio file all the flight data on
18:15here yep okay good a major piece in any investigation is recorders you start narrowing the focus down in
18:25each component will the data confirm an oil pressure problem in the main gearbox look at this
18:38here's the oil pressure warning here's the oil supply gone the flight data recorder shows the main gearbox
18:46oil pressure dropped from 54 psi to zero in less than two minutes that happened fast
18:55if the gearbox had lost all oil pressure the possibility of a catastrophic failure of the gearbox
19:02had to be taken into consideration
19:09uh-huh within days of the wreckage recovery the helicopter's manufacturer sikorsky has questions
19:17about the crash that's right the whole main gearbox sikorsky all right yeah good yeah we'll be expecting
19:27here great they're coming yeah and the faa they want to take a look at the whole main gearbox
19:33it turns out sikorsky and the u.s federal aviation administration or faa are extremely interested in the same piece of wreckage as cunningham
19:49this way come over here when the faa uh and sikorsky uh showed up it seemed they were very anxious about this accident
20:02we need to look at this they unrolled the schematic of the main uh gearbox and said that this is something
20:10that we have to look closely at this isn't the first time this has happened is it
20:23investigators learned that eight months earlier a sikorsky s92 in australia got the same gearbox warning
20:32gearbox pressure gearbox pressure
20:35but that s92 reached land in less than seven minutes without incident
20:45the circumstances are identical
20:51catastrophic loss of oil unusual oil temperature reading same we were conscious about not jumping to
20:58conclusions too early that being said if it was indeed the same problem
21:04that was encountered in australia it was going to be important to take action quickly
21:11is there some flaw in the design of the main gearbox so what went wrong right here the oil filter bowl
21:21the oil filter bowl filters the 11 gallons of oil circulating through the main gearbox
21:27it's fastened to the gearbox with three studs the investigators now focus on this key component here we go
21:41wow two of the studs are gone
21:44it was very obvious once we pulled back the panels that surround the main gearbox that two attachment points
21:51had definitely been compromised there was a gap between oil filter housing and the main gearbox and that's where
21:58the oil in the main gearbox exited so it wasn't a slow leak poured out all at once this discovery confirms what
22:09investigators saw in the fdr data an extremely sudden loss of oil they now have concrete evidence that oil
22:17leaked because of the broken studs so what made the studs fail what does it mean on these ones titanium
22:28oh this looks like galling
22:34galling is a form of wear caused when two surfaces are moving against each other particularly two
22:40different metals under pressure
22:45titanium is prone to galling especially when in contact with steel
22:49when you're trying to tighten a nut onto a stud that has a significant amount of galling it can actually
22:57jam before it's properly tightened in the location it should be in
23:04once fatigue cracking began well it's just a matter of time until failure
23:08it's just a matter of time it's just a matter of time it's just a matter of time it's just a matter of time
23:12Sikorsky studied the australian helicopter's broken studs
23:16and concluded the galling was caused by the steel nuts used to fasten them
23:25here take a look at this
23:26alert to operators of the s-92 replace all titanium studs within a year or 1200 flying hours
23:44six weeks before the newfoundland crash sikorsky issued an advisory to swap the titanium studs
23:50for steel studs they knew the studs could fail
23:55sikorsky had known there was a problem with these studs previously the thing that we found
24:02distressing it was that most of these studs showed some kind of damage on them which this
24:10enhanced visual inspection should have picked up sikorsky said that the titanium studs would last at
24:16least a year cougar got the replacement parts but maintenance didn't think that it was urgent
24:20enough to replace the studs immediately when the accident occurred uh those parts had had just been
24:30recently received by the company and they knew they had to replace these studs eventually with new
24:36steel ones the question now is why did cougar delay replacing the studs
24:55investigators need to find out why sikorsky told operators they could wait a year to replace the studs
25:01now look here the team examines how the s-92s main gearbox was certified all right i got something
25:13sikorsky says possible failures of the main gearbox that could result in a rapid loss of oil are extremely
25:21remote extremely remote yeah what does that mean one in ten million two failures in less than a year
25:32it's not one in ten million basically what they're saying is in the normal lifetime of this machine
25:41the possibility of a total loss of lubricant will almost never happen sikorsky didn't communicate
25:48the urgency of replacing the studs because they didn't understand how severe the situation really was
26:02as the 17 victims of the crash are laid to rest the offshore oil community focuses on the cougar 91
26:10investigation we see this this accident something that we're all in together we're hurting
26:18thousands of people from tourists to world leaders fly in sikorsky helicopters every day
26:23are they at risk from some unknown floor investigators are eager for the medical examiner's report they hope it
26:34will tell them exactly what happened to those on board the helicopter when it hit the water
26:40in the meantime the team reviews the data from the helicopter's recorders hoping to find out how the
26:46pilots handled the emergency situation all right this is at 0945 local dispatch cover 91 we're coming
26:56back to st john's one of the first things that this crew did was uh make a 180 degree turn back towards
27:03the land because it's always much better to make an emergency landing on the ground than in the water
27:09the main gearbox failure we should be getting smells vibrations i don't smell anything they're not
27:17feeling any vibration they're not smelling anything burning it's uh perfectly understandable that they
27:23would want to try to get back to that parking lot of cape spear problem could be with the sensor
27:32as the team continues listening they hear the pilots troubleshooting the crisis
27:37cougar 91 gander you are unable to maintain altitude is that correct in this condition we have to be
27:46down as close to the surface as possible in case of a catastrophic failure for a crew cruising at 9 000
27:52feet in level flight on a nice day the first task when a warning light goes on is to try to figure out
27:59is it an indication system problem or is there some kind of real underlying problem captain who reduces
28:06altitude from 9 000 feet to 1 000 feet the cvr then reveals something changed just under 1 000 feet that
28:16forced the pilots to suddenly ditch oh hell dispatch we're ditching ditching ditching ditching ditching
28:27investigators need to find out what that was let's look at the pinion the pinion is the gear that
28:33transmits power from the main gearbox to the tail rotor this tail or takeoff pinion is being driven
28:40at a high rate and as heat builds up the hardness of the material goes away now you have the potential
28:47for damage on the teeth here you go so what is this supposed to look like
28:59basically uh there were no teeth left on that takeoff pinion in the end without oil in the main gearbox
29:07friction wears away the pinion's teeth stripped clean
29:14no opinion no tail rotor no tail rotor no control
29:20the tail rotor's main job is to keep the helicopter straight it counters the spinning force created by the
29:27large rotor that lifts the aircraft without a tail rotor the helicopter would spin uncontrollably
29:34the pilot's only option at that point is to land the helicopter with no engine power
29:41when the engines are turned off air flowing upwards through the blades should allow for the helicopter
29:46to glide to a safe landing the pilot still has control over the helicopter's overall airspeed and direction
29:56the optimal altitude for such a glide is 200 feet
29:59but the cougar captain kept his altitude at nearly 1 000 feet
30:07why didn't he take it down lower there's a 500 foot hill between him and the airport
30:14he was trying to stay high enough to clear it way too high
30:18all right we're turning call it in we're getting prepared to uh ditch ditching he was at high airspeed
30:30and at 800 feet and high power and that aircraft really was not in a position to be ditched in that
30:40configuration that was in no way a ditching that day that was a crash
30:49investigators of the cougar 91 crash look into the final communications between the captain and first
31:04officer
31:07okay so the checklist says land immediately and we know that's not what they did
31:13fo says checklist is complete we're in a land immediately condition
31:18land immediately means put the helicopter down
31:22even if you're over water or not very flat terrain
31:25but the captain says i'm going to stop descent at 1 000 feet
31:33first officer is telling him that they should put it down in the water
31:36well it's easier said than done
31:40we're in a land immediately condition roger i'm going to stop descent at 1 000 feet
31:44okay checklist is complete
31:53we're in the land immediately condition
31:58i would say that there really was a disconnect in that cockpit the captain had a very strong
32:03personality and as the situation developed he became more and more intent upon making it to land
32:11i'm going for the nearest piece of terra firma i can get to whatever i see first if it's cape sphere
32:16or a parking lot the first officer had more experience in over water flying and ditching scenarios
32:25he used to fly the sea kings for the canadian military but he had a quieter personality there
32:32should have been more interaction between the captain and the first officer despite the uh concerns
32:40that the first officer was trying to convey to him about the need to possibly land immediately
32:47when he didn't hear any noises or sounds he made a decision that he wanted to make and that's called
32:54confirmation bias he wanted to make it back to shore at 09 48 32 the captain says you know i'm thinking
33:04this is a sensor problem why does he think that when they said that the oil temperature was normal
33:13but with a leak it should be spiking they believed that they had probably an oil pump or oil pressure
33:22sensor problem because their oil temperature gauge had not increased at all it was basically showing
33:30what would be expected normally no the oil's reading is normal range a sensor in the main gearbox provides
33:40an oil temperature reading for the crew you know all the oil is gone by now
33:48it's reading the air temp it's reading the air temp
33:51the oil temperature sensor in in the main gearbox of the s92s is a wet sensor if there's no oil
34:01present it's just sensing the ambient temperature within that gearbox
34:09they felt no strange vibrations no no smell and they saw the temperature was normal yeah that makes
34:19sense that's why the guy kept flying they had no idea how much trouble they were in
34:25until the pinion failed
34:31oh hell dispatch we're ditching ditching airspeed 122 matt
34:38but the tail rotor fails just below 1 000 feet too high to perform a safe ditching
34:44they lost directional control of the helicopter and this is probably the most challenging emergency
34:52that any helicopter pilot will face with no engine power descent rate is uh you know usually about 1500
35:00feet per minute so in the best of circumstances this crew only had about 30 seconds to do everything right
35:06is there anything the pilots could have done in those last few seconds to recover
35:15so they lost the tail rotor here and it was all over in less than 15 seconds
35:20the engines shut them down shut them both down shut it down one and two okay nose up nose up
35:32all right we're turning call it in we're getting prepared to uh ditch uh ditching
35:38it's too late the fate of cougar 91 is sealed uh here we go here we go race
36:08the ditching began from 800 feet so those control inputs were all initiated too high
36:14so the result was essentially sinking like a rock
36:20the captain in the end he unfortunately wound up in a position where he didn't have enough energy
36:27remaining to land safely on water the main gearbox makes helicopters top heavy
36:37once they hit water they tend to capsize and sink quickly aircraft did strike the water with a high
36:44vertical descent and it would not have been on the surface of that water for very long
36:50at all were the passengers doomed once cougar 91 hit the water
36:57investigators finally get the medical examiner's report
37:03the conclusion is shocking
37:16they all survived the crash
37:17instead all 17 victims died from drowning
37:24it was a bit of a shock to think that 17 people had survived that impact
37:30but only one had survived the accident
37:36so why does only robert decker survive how was he able to escape
37:42investigators start by looking at where he's seated
37:45so decker is seated in 3d on the right hand side the team has already determined that as cougar 91 hit
37:53the surface it rolled left and quickly filled with water decker was lucky to be on the right side
37:58undo harness find a window get out get up to the surface that's if you're not too badly injured
38:05but look at this look at it somehow he gets out in a helicopter that is sinking past 30 feet
38:17he holds his breath he gets to the surface all in water that is just barely above freezing
38:22even with a survival suit on uh as soon as you get immersed in that cold water
38:30that cold water is going to rob your ability to hold your breath
38:34and he floats there for an hour and 20 minutes before he's rescued
38:40that man is lucky to be alive
38:41a helicopter with a design floor gearbox pressure gearbox pressure instruments with a misleading readout
38:58the temperature looks normal and a cockpit with differing assessments we're in the land immediately
39:05condition brace brace brace
39:16only one person survived the resulting crash
39:23what did robert decker do to ensure his survival
39:30it's very important to analyze how individuals would have gotten out
39:34and how the individuals that didn't get out what affected their ability to exit the aircraft
39:45investigators hope the lone survivor can provide some answers
39:50eight months after the crash of kooka 91 decker testifies at a hearing in st john's newfoundland
39:56the helicopter was sinking quickly with its port side down and it instantly filled with water
40:04it was as if it was sinking the same way it was dropping through the sky
40:11i undid my seat belt and i pulled myself out through the window
40:15the window would have been directly above me because um as it was sinking on its side
40:21when he first became conscious of of where he was in the environment he was in
40:30he looked up and he could see a light in the distance and because the fuselage was already opened up
40:38he was able to get out
40:39then it was a long i guess ascent to the surface i kind of had my hands above my my head
40:49and i could look up and i could see it was getting brighter and brighter and i guess eventually my
40:56arms broke the surface and i could tell that i survived the helicopter crash
41:03he said that he attributed some of it to to luck as well as his physical abilities
41:16a crash into water is traumatic most passengers will be stunned and unable to act quickly research
41:24shows that as many as 15 percent of passengers fail to take any action in fact drowning is the leading
41:31cause of death following a helicopter ditching or crash into water with the water temperatures we had
41:39even with a survival suit on as soon as you get immersed that cold water is going to rob your ability to
41:48hold your breath that's why survival training is a critical rehearsal for such an event
41:53when investigators dig into the training of all the people on board cougar 91
42:01they discover that everyone had received mandatory survival training in a simulated ditching
42:08if the helicopter sinks you have to wait till it's fully submerged and then you kind of take your
42:13last breath you release your seat belt your hands already on the ledge and you pull yourself out
42:18but decker was the only passenger who had cold water experience in his youth he often sailed in
42:25the atlantic and had capsized in the cold sea when the helicopter suddenly filled with icy water
42:32i could react instinctively it was like a reflex to take a breath and to hold it and to stay calm until
42:38i could get to the surface while decker's training and cold water experience played a key role in his
42:44survival safety on board a helicopter begins long before it lifts off
42:52the only way to keep every offshore worker safe is to keep every helicopter in the air
42:59in its final report the transportation safety board makes recommendations that will improve safety
43:04not just in the sikorsky but in all helicopters
43:08emergency underwater breathing apparatus are now mandatory for all occupants of helicopters involved
43:16in overwater flights the unit provides approximately two minutes of air this was another key change that
43:25took place as a result of this accident and again not just in canada but around the world the tsb
43:33also recommends reviewing how long a helicopter should be able to run without any oil in the main gearbox
43:43it was a broad and deep investigation that uncovered every safety issue that there was to uncover about
43:50that helicopter and about flying in the offshore i think our recommendations made flying in the offshore
43:58we're much much safer
44:06you