There is a news conference scheduled for 14:00 Newfoundland Time (10 minutes from now) where the TSB are going to announce their intention to recover the wreakage. Perhaps there will be some detail regarding the condition of the aircraft, but if they plan to recover it it must be in at least a few big pieces giving a clear indication of how hard it hit the water?
Record #7 Cadors Number: 2009A0212
Reporting Region: Atlantic
Occurrence Information Occurrence Type: Accident
Occurrence Date: 2009/03/12 Occurrence Time: 1215 Z
Day Or Night: day-time Fatalities: 1 Injuries: Canadian Aerodrome ID: Aerodrome Name: Occurrence Location: 472605N515658W
Province: Country: CANADA World Area: North America
Reported By: NAV CANADA AOR Number: 105029-V1
TSB Class Of Investigation: 3
TSB Occurrence No.:
Event Information
Engine oil problem/Forced landing/Collision with terrain/Diversion
Aircraft InformationFlight #: CHI91 Aircraft Category: Helicopter
Country of Registration: CANADA Make: SIKORSKY Model: S92A
Year Built: 2006
Amateur Built: No Engine Make: GENERAL ELECTRIC Engine Model: CT7-8A Engine Type: Turbo shaft Gear Type: Land Phase of Flight: Cruise
Damage: Destroyed Owner: COUGAR HELICOPTERS INC. Operator: COUGAR HELICOPTERS INC. (4791)Operator Type: Commercial Detail InformationUser Name:MacQuarrie, JackDate:2009/03/12 Further Action Required:Yes O.P.I.:Maintenance & Manufacturing Narrative:CHI91, S92, enroute from St. John's (CYYT) to the Hibernia Oil Platform at 12:15Z, declared MAYDAY due to a main gear box oil pressure problem and requested to return to St. John's. Air Traffic Control cleared the flight as requested. At 12:25Z aircraft ditched at position 472605N515658W.
Correct me if I am wrong but I believe that your wondering is should a gearbox puke out all it,s lubrication ....do the blades keep turning?
Yes they do...until the gears and bearings within the box reach a temperature point that begins to bake the residual lubrication. Without any lubrication , the metal to metal contact and extreme forces that a 15 ton helicopter put upon them, begin to fail as well as build incredibly high frictional forces.
At this point, further application of power can overcome this rapidly increasing friction and keep the blades turning but at some point either the power runs out or the incredible heat build up causes a catastrophic failure and either a blades will begin to slow and eventually sieze or the mast / transmission will fail. At this point your a greasy manhole cover and gravity wins another one
As the gearbox fails, the increasing friction also precludes successful autorotion.
With some operators, an impending gearbox failure (high teps and or low pressure) calls for a Land As Soon As Possible and in other cases....a Land or Ditch IMMEDIATLY I
I am curious as to the S92,s RFM Emergency Checklist and/or Cougar,s ECL calls for with respect to Gear Box malfunctions.
Last edited by rumline : 13th March 2009 at 19:13.
Reason: the usual grade IV spelling & grammer
I appreciate it varies from type to type, but are there any quantifiable indications as to how long this might take?
I ask as I would appreciate the experience of other pilots how to treat this type of situation, when overflying an area of hostile terrain, either unsuitable to land, or remote from help (in my case more likely to be over urbanized, mountainous, forested or desert area, rather than the ocean).
Naturally a bias would lean towards Land Immediately, unless otherwise indicated in the relevant type POH, and of course, prevention of getting into this state in the first place, assuming I had influence over the contributing factors.
This is the only S92 accident in which MGB is identified as a possible issue in these databases, and the only fatal S92 accident in these databases. Is this the first S92 accident in which fatalities have occurred?.
The machines that I am intimate with have never stated outright what those figures are.....and I doubt many will ....unless it.s a MIL Spec proviso (ie Blackhawk)
The figure that gets bandied about by the techs that dig into these hard-to reach places is 30mins....
I have known Bell mediums to sieze within 15mins ...others to have sustained serious damage (scrapped GB) in as little 3 mins...
There are many factors as to whether a gearbox holds together or self-destructs. Things like rate of fluid loss, payload being carried, ambient air temp, transmission design, fluid being used .....all the way to the tolerances within individual boxs (no two are exactly alike)
I have personally had two trannys puke thier fluid out....once from 55psi to Zero in about 30secs (fortunatly was just in the hover....whew!! and another it dropped at a rate about 5psi /min (where I elected to carry on to first landfall....no damage...a/c returned to service)
It is my personal evil monkey lurking in the closet when it comes to helos....You might have 2 hydralics, 2 engines, 2 generators, 2 inverters, instrument redundancy......but there,s only one tranny....take care of it!
In the event of possible MGB failure, I think all aircraft types would have a Land/Ditch Immediately policy. Obviously, that doesn't apply if you have an emergency lubrication system, or that system has run for its prescribed amount of time. But once you have a gearbox about to fail, there is only one place you should be - On the ground / Water.
As to Autorotation. That isn't a requirement for a Gear Box problem, although I gather that was included in the early reports of this accident. I always understood that in the event of gearbox oil running out, the best policy was to land or ditch with power on, in order to overcome the increasing friction. I seem to remember a story of a Puma (332 or 330J) losing its lubrication and just making it to a deck that was close by - As they lowered the lever on landing, the blades made about 3 rotations and shuddered to a stop together with the smell of hot metal.
Special 25.....know a 212 that lost its lube...flew for about 13min before landing and upon throttle roll-off....blades siezed and spun the machine on the ground...
If you are involved in any way with the S92 then you will know what the issues are, I think at this stage we shouldn't speculate but think of all involved.
Only seven fatal accidents in "newer" Sikorsky helicopters (S76A or later) in last 10 years in NTSB database. None of these show MGB failure as a probable cause, however, in some cases, no cause determined.
Searching data bases for accidents may not reveal nearly enough information to mold an informed opinion.
Many incidents occur that are resolved at the company level...
Some between the operator and the manufacturer
Others between the Minister, the Company and the Manufacturer.
ie: A MGB return line cracks and leaks oil out....oil pressure drops and pilot returns to base before there is a catastrophic failure.
Oil line is replaced and machine returns to service.
Perhaps the material used to manufacture the line wasn,t resilient enough....or perhaps the stand-offs were not positioned properly....but the fix is made. The company examines other similiar types and also replaces those lines with a stronger one....
Now we have a known issue ...and all the pilots/engineers all know about it but thats where it ends.
Perhaps chatting to collegues reveals that they too, have had similiar incidents....but again...it is possible that a known fault/flaw can go for years before being fully addressed
Terrible news that no one found.
Condolences and peace upon those left behind.
I always understood that in the event of gearbox oil running out, the best policy was to land or ditch with power on, in order to overcome the increasing friction. I seem to remember a story of a Puma (332 or 330J) losing its lubrication and just making it to a deck that was close by - As they lowered the lever on landing, the blades made about 3 rotations and shuddered to a stop together with the smell of hot metal.
Scenario2:
Quote:
Originally Posted by rumline
know a 212 that lost its lube...flew for about 13min before landing and upon throttle roll-off....blades siezed and spun the machine on the ground...
Would it make sense then, in the above scenarios to:
scenario1 - (Splash 25) override the governor and keep power on when lowering collective
secnario2 - (rumline) roll off power very gradually (I assume this could pose some other risks, depending on state of MGB and various temps /stresses)
i.e. in both scenarios keep one eye glued to RRPM?
In the case of the 212.....the ECL (at the time) called for Land As Soon As Possible)
The PIC elected to fly to the first floating site suitable for landing ....at this point your well outside anything the checklist could possibly cover and just relieved to know your down.
As the tranny thrashes in its death-throes .....how to roll off the throttles was probobly the last thing on thier mind!
If it was MGB problems, all you have to do is read the S-92 forum. There has been a few problems with the MGB and the 92. The concentration however has been on it's FAR crashworthiness certification vs other helo models non-FAR(fully compliant) crashworthiness certification.
Personally I want a guarenteed MGB above anything else. We have procedures for almost all failures, but a MGB failure is unthinkable- hydraulics gone on a big machine? Altenators gone? Rotor rpm?
Again, I hope for the best for those unfortunate to be involved, but this must cause some investigation and rectification.
Just heard on the radio that search will continue until it gets dark this evening (March 13) then will probably resume tomorrow as a recovery effort.
The TSB plans on using a remotely contolled vehicle to conduct the underwater search. More news here: CTV.ca | Search for chopper crash survivors continues Friday
I know most people seem to be focusing on the MGB and there was talk of past issues.
Am I correct in thinking that one of the launch machines (Norske Helicopters) had a problem involving Loss of MGB pressure in the first few hours of flying ? Think it was traced to a plastic component in the pump that had failed a bit earlier than expected.
Then there was an incident in Brunei quite recently that necessitated a forced landing. I think that was Main Transmission related, but not sure if the final conclusion has been reached.
Is this a fundemental problem with the 92 Gear Box and Main transmission or are these isolated events. Seems like a lot of issues for such a new aircraft. Hope they don't ground it as the UK Search & Rescue system depend on them now that the AB139 isn't working either !
I still feel that if you have not got oil pressure you are going to land, if you have a little make sure it don’t get to hot, if you have other indications along with the lack of or low pressure, the only place you are going is down, low, slow and ready for the possible wet arrival.
Any run dry time advertised by any manufacture in my humble view is an advisory regarding your ability to transition from your altitude to a possible safe controlled landing on ground or water.
No gear system will run reliably without oil, it cools lubricates and is the life blood of the transmission system.
After looking at the flight data available on line and the noting the point that they turned back to the shore, how close were they to the destination rig?
My comments above are general ones only and in no way try to explain any aspects of this tragic event.
Outhouse.
Last edited by outhouse : 14th March 2009 at 09:17.
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