Bristow S92 down west of Bergen Norway
Well it did start with an A....and end with an E so close enough I guess.
Well just on your bullet points, the second one is the same as the Super Puma. I don’t know when the APU is routinely started, other than at start up. For example I don’t think it is started prior to a normal landing or a low level SAR hover? Is it just started in response to some first level failure eg a generator failure. My point is that an APU is only any use if it is on, and it takes a while to start up so in the event of a sudden fairly catastrophic issue it is of no use. Of course the emerg checklist will have lots of progressive scenarios that could ultimately result in ditching after several minutes, but the real world is not always so reasonable and predictable.
Some operators do start the APU before landing, but I have no clue if Bristow Norway do, or for SAR low level. It is possible, because the first time I encountered the practice was with ex-Norsk pilots that joined us, who wanted to continue the practice.
I of course defer to S-92 operators on the detail, but I suspect the system/scheme would be similar.
(On the other hand, our Navy ended taking the floats off of the Seahawks due to a problem with them interfering with the crew exit from the cockpit, so it appears that S-92 is better set up with the floats, perhaps due to a few lessons learned).
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Hoist wire spooling out by itself after the hoist excercise ?(forgotten the hoist ON?) , at speed reduction hoist wire swinging up in the rotor causing damage and vibrations leading to a decision to ditch?
Or hoist cable cut when the plan was to activate the floats? (I can see that happening, being prepared for hoist cut during the hoist ex.)
From memory, on a similar type the hoist cable could not be cut unless out at least 0.6m.
Or hoist cable cut when the plan was to activate the floats? (I can see that happening, being prepared for hoist cut during the hoist ex.)
From memory, on a similar type the hoist cable could not be cut unless out at least 0.6m.
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I guess there is one key question - was the ditching intentional or unintentional? If the former, then I would not expect the crew to rely on AFDS anyway and would fire the floats manually before touchdown.
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Lonewolf, I’m assuming if you were starting the APU for winching ops for utility hydraulics, the hoist motors were powered by hydraulics? Us Army H-60 hoists are all electric now, though I think in the past some were hydraulic and Navy systems may still be?
Remember also that the battery utility bus powers the fire suppression system for #1 Eng and APU, converted AC power to the DC primary bus is required for the #2 Eng fire suppression to work.
I used to question this lack of redundancy but it’s probably the best compromise in systems design to handle the most likely scenarios for dealing with fires, meaning a situation that ends up with your #2 engine on fire with no converted AC power to fight it means a lot more has gone wrong in your day than just a #2 engine fire.
I think you pointed out, a situation that droops the rotors below 90% that kicks off both generators or cascading failure of the AC electrical system (both AC generators and the APU generators all failing together), would seem unlikely and a power on ditching is probably what happened in this situation, so it becomes more of a possibility of a human factors or SOP issue why the floats weren’t deployed than a systems failure.
FltMech
Remember also that the battery utility bus powers the fire suppression system for #1 Eng and APU, converted AC power to the DC primary bus is required for the #2 Eng fire suppression to work.
I used to question this lack of redundancy but it’s probably the best compromise in systems design to handle the most likely scenarios for dealing with fires, meaning a situation that ends up with your #2 engine on fire with no converted AC power to fight it means a lot more has gone wrong in your day than just a #2 engine fire.
I think you pointed out, a situation that droops the rotors below 90% that kicks off both generators or cascading failure of the AC electrical system (both AC generators and the APU generators all failing together), would seem unlikely and a power on ditching is probably what happened in this situation, so it becomes more of a possibility of a human factors or SOP issue why the floats weren’t deployed than a systems failure.
FltMech
APU use.
As I vaguely recall:
Re APU use.
If you are landing offshore for a rotors running turn around AND are planning to go to idle you start the APU pre-landing. We did not usually go to idle. Not going to Idle. —- APU not required.
If for some reason you were doing a lot of quick inter-rig stuff and had to go to idle you just kept the APU running. Of course not exceeding the APU Running VNE of 150 Kts.
If you are going to shut down you start the APU. ( It would be embarrassing to have a hot shutdown and not be able to motor the starter.)
Landing back at base you start the APU when taxing off the runway in to your spot.
Landing at an airport away from base start the APU, shutdown the engines leave the APU running if you are just going to fuel, load. and go.
Before start you start the APU to get the Air conditioning or heating running and do all checklist items up to the actual start.
Electrical problems …start the APU.
If it is SOP to have the APU up and running during SAR hoisting I have no idea.
One question I have asked many times is why you would select gear-down for ditching. ( being an bush float guy in another life—-why would you want gear down causing drag and a nose down pitching movement. if you want to blow it down after landing you could do that the gear is not going to foul the floats.) is it perhaps because of the location of the immersion switches?
Re APU use.
If you are landing offshore for a rotors running turn around AND are planning to go to idle you start the APU pre-landing. We did not usually go to idle. Not going to Idle. —- APU not required.
If for some reason you were doing a lot of quick inter-rig stuff and had to go to idle you just kept the APU running. Of course not exceeding the APU Running VNE of 150 Kts.
If you are going to shut down you start the APU. ( It would be embarrassing to have a hot shutdown and not be able to motor the starter.)
Landing back at base you start the APU when taxing off the runway in to your spot.
Landing at an airport away from base start the APU, shutdown the engines leave the APU running if you are just going to fuel, load. and go.
Before start you start the APU to get the Air conditioning or heating running and do all checklist items up to the actual start.
Electrical problems …start the APU.
If it is SOP to have the APU up and running during SAR hoisting I have no idea.
One question I have asked many times is why you would select gear-down for ditching. ( being an bush float guy in another life—-why would you want gear down causing drag and a nose down pitching movement. if you want to blow it down after landing you could do that the gear is not going to foul the floats.) is it perhaps because of the location of the immersion switches?
Last edited by albatross; 6th Mar 2024 at 14:48.
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Electrical problems …start the APU.
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EDIT::
2.23 RESCUE HOIST SYSTEM {my note: sometime in the 00's}
{snip} The hoist is hydraulically powered by the backup hydraulic pump. Speed is variable from 0 to 215 fpm for the Breeze-Eastern and 0 to 250 fpm for the Lucas-Western hoist. {snip} The hoist contains 200 feet of usable cable, a guillotine-type cable cutter, and an automatic cable brake. The first and last 20 feet of the cable are bright orange to warn of end approach. The hoist hook is attached to the cable end by a ball-bearing swivel.
Power to operate the rescue hoist system is supplied by the No. 2 dc primary bus through the RSQ HOIST CONTR circuit breaker. Backup (emergency) hoist operation is powered by the dc essential bus through the RSQ HOIST AUX CTRL circuit breaker.
Power to operate the rescue hoist system is supplied by the No. 2 dc primary bus through the RSQ HOIST CONTR circuit breaker. Backup (emergency) hoist operation is powered by the dc essential bus through the RSQ HOIST AUX CTRL circuit breaker.
Remember also that the battery utility bus powers the fire suppression system for #1 Eng and APU, converted AC power to the DC primary bus is required for the #2 Eng fire suppression to work.
As to the S-92, does it use an electric motor for its hoist, or does it also use hydraulic power?
Last edited by Lonewolf_50; 5th Mar 2024 at 19:20.
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Bearing in mind that the crew survived, what actually happened here will be revealed in time so I, for one, see little point in protracted speculation on the cause. 
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FltMech
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What would be far more useful and enlightening would be input from an actual SAR S-92 operator, ideally Bristow.
Any on here?
Any on here?
On the video the aircraft is initially inverted on the seabed, then the footage changes to it upright but still on the seabed. At 1:13 to run you can clearly see the aircraft now upright and the twin hoist is separated from the hoist support strut with the outboard hook missing. It is possible that the missing hook was ripped off when the hoist mount was damaged. It is also possibly that the hoist frame was used to right the fuselage, though why they then attempted the fuselage recovery using the undercarriage I cannot guess? Possible the video is not stitched together chronologically?
I see in #132, 206Fan indicated a video of salvage is also posted to Facebook. Perhaps it is the same as in #112, or a more extended version, but it is necessary to join the group to access it.
I wonder whether this S-92 is now only still suitable as a source of spare parts? If so, I hope none of the drivetrain parts critical to flight safety find their way back onto any operational helicopter.
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Not sure this design flaw has ever been fixed by Sikorsky other than increased monitoring -
https://skybrary.aero/accidents-and-...north-sea-2016
https://www.offshore-technology.com/...60853/?cf-view
I believe there were a handful of identical issues going back previously also as they issued an emergency AD just before that accident above.
https://www.ainonline.com/aviation-n...2-emergency-ad
Just a post to highlight previous loss of control events. Most likely unrelated to this event but you never know.
https://skybrary.aero/accidents-and-...north-sea-2016
https://www.offshore-technology.com/...60853/?cf-view
I believe there were a handful of identical issues going back previously also as they issued an emergency AD just before that accident above.
https://www.ainonline.com/aviation-n...2-emergency-ad
Just a post to highlight previous loss of control events. Most likely unrelated to this event but you never know.
Replying to a different topic, the recent FAA Emergency Airworthiness Directive AD #: 2024-05-51. Both Sikorsky and the US Army determined this to be a minor issue requiring no action, but the FAA dissented and forced compliance. I'm curious if anyone here can remember a similar instance with such a dramatic difference in reactions. Regardless, I don't think it played a factor in the thread topic.
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What would be far more useful and enlightening would be input from an actual SAR S-92 operator, ideally Bristow.
Any on here?
Any on here?
When these matters arise it pays to zip ones lip and sit quietly behind the daily issue of the Guardian or whatever crossword now enjoys with ones Tea.
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Shame you don't follow your own advice - of course I wasn't suggesting they post under their real name.
Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.
Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.
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Originally Posted by [email protected]
Shame you don't follow your own advice - of course I wasn't suggesting they post under their real name.
Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.
Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.
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A very experienced pilot friend and a very smart guy (don’t tell him I said that!) looked at these posts and said “Humm aren’t you folks getting focused on the seaworthiness of the lifeboats on the Titanic and kind of ignoring the cause of the ship hitting the iceberg?” He has a way of saying things like that. He will not post on aviation sites and seldom, if ever, even looks at them, except when I occasionally drag him, kicking and screaming, over to my computer screen. He has a point.
Last edited by 212man; 7th Mar 2024 at 18:19.
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