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Firefighting B412 down in Spain 11JUL2021?

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Firefighting B412 down in Spain 11JUL2021?

Old 20th Jul 2021, 06:59
  #21 (permalink)  
 
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From the low RPM at the very end of the video I'd guess failure of the input from cbox to main transmission. With the engines suddenly being released of load they would tend to overspeed before systems caught up to control.

From the manual.

MAIN DRIVESHAFT FAILURE

INDICATIONS:
Left yaw.
Rapid decrease in ROTOR RPM.
Rapid increase In ENG RPM (N2).
Illumination of rotor RPM caution light with audio.
Possible increase in noise due to:
Overspeeding engine turbines.
Overspeeding combining gearbox.
Driveshaft breakage.
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Old 20th Jul 2021, 07:17
  #22 (permalink)  
 
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Isn't there one freewheel unit per power section in the CBOX? Unless I'm mistaken both freewheel units would need to go kaput to lose output drive from the CBOX.
Agreed but one freewheel failure would give the same loss of power as a single engine failure and a controlled ditching as per the video. The engine with the failed freewheel would accelerate under no load which would explain the noise as well.

I think a driveshaft failure from the Cbox to the MRGB would have resulted in a far more dramatic entry to the water.
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Old 20th Jul 2021, 09:25
  #23 (permalink)  
 
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If it was just a single engine failure he would have sat there on the water fat dumb and not so happy whilst the good engine kept everything turning enough for him not to turn turtle. If it was a -DF engine he probably would have been able to hover on one engine without entering the water. Nah, he's lost all power to the MGB I reckon.
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Old 20th Jul 2021, 09:42
  #24 (permalink)  
 
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If it was just a single engine failure he would have sat there on the water fat dumb and not so happy whilst the good engine kept everything turning enough for him not to turn turtle
And then what? Not enough power to get airborne again and God knows what shock loading to the transmission from TR impact with the water.

A water landing in an aircraft designed for it (done it in a Sea King) is exciting enough and you need a boat shaped hull to manage a SEWTO unless you have a ridiculous amount of power available on the remaining engine. If you are still attached to a water bucket this will be impossible.

On water entry without sponsons or flotation gear you are going to roll inverted regardless.

A driveshaft failure would have produced a lot of yaw - of which there is none in the video - and a harder impact.

If it's not a single engine failure/ rundown/freewheel failure I'll be very surprised.
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Old 20th Jul 2021, 11:49
  #25 (permalink)  
 
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Originally Posted by [email protected] View Post
...A driveshaft failure would have produced a lot of yaw - of which there is none in the video - and a harder impact.
Maybe the driver was like Fangio on the pedals and reacted instantly to keep it straight. Dunno I've never been in the 412 simulator to give me a better educated guess of what happened. If it was an old heavy -SP or -HP with a tank of gas he would have run out of oompf OEI, but if it was an -EP I find it hard to believe that 1133 horses from one good engine wouldn't keep him from dunking it.
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Old 20th Jul 2021, 11:56
  #26 (permalink)  
 
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Crab,

You have not flown a Chinook have you?

We used to do a full engine shutdown and re-start with them.....and do running type takeoffs from water as part of the conversion course when possible.

Back into that old SAR Ready Room Lounge Chair old fella.....and stick to your Sea King construct.

Single engine running takeoffs from the water in a Bell 412 would be a unique experience....yet to be done by anyone I suppose.

The 412 appears to have some kind of problem that resulted in it winding up in the water....with the results seen in the video,

That limits the "what If's" to what happened....as there was no possibility of it making a take off of any kind after that problem manifested itself.
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Old 20th Jul 2021, 18:24
  #27 (permalink)  
 
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Sasless - the shape and size of the chinook hull is what I expect lets it do that - I mentioned a boat like hull for water takeoffs which is almost what the chinny has. It also has an excess of power.

Remember I am still flying every day so don't have to rely on misty-eyed recollections of past glories

Gulli - I presently fly the 412 EP and there is not a chance with a bucket of water underneath of staying airborne OEI nor doing a SEWTO. The driveshaft failure in the sim gives a very marked yaw.
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Old 20th Jul 2021, 18:39
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The only time you get Misty Eyed is when you have to get up out of that Lounge Chair and change the channel on the Television!
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Old 20th Jul 2021, 19:35
  #29 (permalink)  
 
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No, I have a man to do that for me old boy
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Old 20th Jul 2021, 21:32
  #30 (permalink)  
 
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Originally Posted by [email protected] View Post
Gulli - I presently fly the 412 EP and there is not a chance with a bucket of water underneath of staying airborne OEI nor doing a SEWTO. The driveshaft failure in the sim gives a very marked yaw.
As soon as the bucket touched the water its weight was no longer a factor in pulling that thing out of the air.
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Old 21st Jul 2021, 03:22
  #31 (permalink)  
 
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If it was a -DF engine he probably would have been able to hover on one engine without entering the water
Don't have any idea what the performance capability he might have had (altitude, gross weight, temp etc) but was obliged to do a single engine run on landing in a 412 at one time, sea level, 3-400 lbs fuel, plus a number of pax, after unloading pax hover taxied back to the apron. The very low RPM at the end suggests to me no drive at all.
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Old 21st Jul 2021, 04:52
  #32 (permalink)  
 
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Originally Posted by megan View Post
Don't have any idea what the performance capability he might have had...
Your 412SP could crank out 1025 SHP 2.5 minute OEI. If this one was a 412EP he had an extra 108 horses available in an airframe probably slightly lighter than the offshore configured SP you mentioned. I reckon he could arrest the descent and IGE hover OEI no problem at all after the bucket was in the lake. Which suggests to me he had no engines delivering usable power.
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Old 21st Jul 2021, 11:23
  #33 (permalink)  
 
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I kept waiting to see water dumped...or the entire line and bucket jettisoned......both of which are simple to do.

As it was not done....then you have ask why it was not done.

If your bucket is adjusted to limit the amount of water you take in.....a manually done procedure...then going over weight would have only occurred if the Dip Site parameters changed or the max weight calculations were done for less than full fuel and more fuel was aboard.

If using the US Forest Service Load Calculation system....over weight would not be a factor due to how conservative their performance calculations are determined.

Gordy can explain how that works, if he will, as he does lots of US Forest Service work with multiple types of aircraft.
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Old 21st Jul 2021, 13:20
  #34 (permalink)  
 
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Colleagues who have flown the 412 in firefighting role in Cyprus agree that with a full or even partially full bucket, OEI performance is not possible, other than to take you to the scene of the accident.

It is not unusual to be pulling 100% Tq lifting the bucket and having to make a very gentle transition because there is no excess power available.

It looks to me as if he slowly inches forward to begin the transition and realises he is up to or exceeding his Tq limit and tries to recover to the hover when the malfunction occurs.

We all know that if a mechanical element is going to give up the ghost it will do so under maximum strain which is where he would be in that scenario.

The amount of yaw is tiny, as you would expect from a single engine malfunction rather than the very large yaw you would experience with either a driveshaft breakage or a double engine failure.

He droops the Nr by trying to cushion the water entry at high AUM on one engine and, since he doesn't release the bucket, he is now attached to a large sea anchor.

He has also just put the TR into the water with all the shock loading one might expect - I certainly wouldn't be trying to fly again in those circumstances.

He is low over the water and has an armful of power, presumably single pilot, so I think it is unrealistic for armchair quarterbacks to suggest he had time to pickle the load - especially if, as I suspect, he had a freewheel let go and was trying to work out what the failure was whilst preparing for water entry.

I've done plenty of firebucketing at MAUM, albeit on a Wessex, and I think he can consider it a job well done just surviving a malfunction in those circumstances.
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Old 21st Jul 2021, 14:29
  #35 (permalink)  
 
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Having a bit of firefighting experience with Bell 205's and 206's using the Bambi bucket....you are quite right about Max Power takeoffs.

My suggestion was at some point prior to the malfunction....lightening the load by mashing the bucket dump button would have gone a long way towards preventing what happened.

After the malfunction you are quite correct in your comments....that bucket full of water determined the vertical trajectory and then became that sea anchor you mentioned.

Also....if you find yourself right at the max limits on power each takeoff....you might want to rethink your bucket capacity and cinch that bucket in a bit to give you some "Uh Oh" Power Reserve.....before it becomes an "Aw Shit!" deficit.

if the aircraft is too heavy....a simple button push puts some water back into the pond....where you can come back and dip it out on another cycle to the fire.

In the USA....firefighting with helicopters is less about putting out the fire and more into safely making money throwing water at the ground.

USFS Rule encourage that as they want to have as few crashes and loss of lives and injuries as possible during the Fire Season.
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Old 22nd Jul 2021, 05:42
  #36 (permalink)  
 
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Originally Posted by SASless View Post
In the USA....firefighting with helicopters is less about putting out the fire and more into safely making money throwing water at the ground.
USFS Rule encourage that as they want to have as few crashes and loss of lives and injuries as possible during the Fire Season.
You know it----raising the humidity one bucket at a time....

A fire is not out until the team has made their overtime allotment for that roll---I may or ay not be jaded at this point in my career.....lol

Originally Posted by SASless View Post
If using the US Forest Service Load Calculation system....over weight would not be a factor due to how conservative their performance calculations are determined.
Gordy can explain how that works, if he will, as he does lots of US Forest Service work with multiple types of aircraft.
Yep, I can do that, basically the USFS takes about a 10% download on performance if carrying people, (HOGE---Hover Out of Ground Effect), in simple terms... 5,000' 30 C go tot the carts and the helicopter is able to lift "X", we deduct about 5-10% depending upon THEIR chart... We then deduct EW, pilot weight, hour and half of fuel weight based upon their chart and what we are left with is our "allowable loading" for the day.

We also complete a HOGE-J number which is our allowable weight to lift WITHOUT the download--as it is assumed this is on the "hook" and is "jettison able" hence the J.

This is the chart we compete daily for expected altitude / temperature of where we are flying:
Attached Files
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Old 22nd Jul 2021, 07:36
  #37 (permalink)  
 
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Seems eminently sensible - it gives you a 10% thrust margin to allow for manoeuvring with the full bucket in the hover.
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