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-   -   Police helicopter crashes onto Glasgow pub (https://www.pprune.org/rotorheads/528850-police-helicopter-crashes-onto-glasgow-pub.html)

RVDT 8th Mar 2014 11:59

Although not inconceivable in turbulence, flying that far uncoordinated to spill things would be unusual.

I and others have sent many years with a full coffee cup just sitting on the floor and it doesn't spill.

This gentleman knows how to maintain coordination!

From 2:10 is the relevant bit.


Art of flight 8th Mar 2014 12:33

Fantastic!

falcon900 8th Mar 2014 12:50

But how long does it take for a few kilos to exit from left to right, or for that matter, rear to front? The divider between the supply tanks doesn't extend all the way to the top ( nor as far as I know does the divider between the supply tanks and the main), so in the right conditions, a lot of fuel could move quite quickly surely?
In fact would 2 kilos not do the trick, and make the tank contents more or less the same?

SilsoeSid 8th Mar 2014 14:27

So, if the aircraft was indeed tumbling (eye witness accounts) for whatever reason, the 76kgs of fuel recovered from the main tank, could have come from the supply tanks. This would mean that the warning lights may not have come on before the tumbling occurred as each tank could have had 38 kgs each, which is above the level at which either of the fuel warnings would come on :suspect:

awblain 8th Mar 2014 14:48

That's true, Sid.

But.. it couldn't have been "tumbling" for very long, rotors stopped, from 1000 feet - about 5 seconds? It ended up nose down, the supply tank to main tank flowback ports - "overflow channels" aren't very big. It seems difficult to see how the supply tanks could drain so fast or so completely, since any remaining fuel would pool below the "overflow channels" against the forward lower edge of the supply tanks as it rested in the pub.

Plus, fuel warnings were registered in the system.

Wiggins61 8th Mar 2014 16:36

If the aircraft was nose down in the pub would not most of the fuel drain back into the main over the top of the seperator.

skadi 8th Mar 2014 17:07


If the aircraft was nose down in the pub would not most of the fuel drain back into the main over the top of the seperator.
There is no seperator ( with a top ) between the main and supplytanks. In fact they are two seperate tanks, connected with the two small overflowholes and in between the holes the lines from the XFER-pumps.


skadi

falcon900 8th Mar 2014 17:49

I dont think the angle of the aircraft in the pub roof would have been steep enough to spill much, but the impact could have pushed the lot over the fence. And if all the remaining fuel was where it should have been in flight, ie in the supply tanks, then the transfer pumps should have been off, as there was nothing left in the main tank to transfer...

skadi 8th Mar 2014 18:09


but the impact could have pushed the lot over the fence.
Look at the pics in #2668! As I said in my last post, there is no fence ( like in the supplytanks ) between main and supplytank! Just the two small overflowholes connecting two seperate tankbladders!

skadi

falcon900 8th Mar 2014 18:23

My mistake Skadi. The impact could not have caused much to go through the overflow holes, but on looking at the diagrams again, perhaps I was too hasty in suggesting there could not have been much post crash drain down.

SilsoeSid 8th Mar 2014 19:38

Having just printed out figs 3&4 I wondered, has anyone put a figure on the angle that the ac was resting at in situ?

Thanks for the post 2668 RVDT :ok:

puntosaurus 8th Mar 2014 21:09

Guys, I think you're flogging a dead horse. The AAIB would never make a statement like this...

It has also been confirmed, by examination and measurement of the internal design features, that this was the fuel disposition at the time of the accident.
unless they were sure of their facts.

They've clearly looked at the geometry of the tanks and the resting position of the helicopter after the crash. By finding the supply tanks effectively completely empty they have ruled out the possibility of post crash drainage.

falcon900 9th Mar 2014 10:23

It occured to me last night that the only way the supply tanks could have emptied to zero and 0.4kg, the contents reported by the AAIB, would have been if the aircraft was standing on its nose, which of course it wasn't. Fuel could have spilled out of the supply tanks at the angle at which it was lodged in the pub, but there would have to have been fuel in the tanks to start with, and it wouldnt have been able to drain down to zero and 0.4kg at that angle.
Returning to the question of left/right asymetry, I do still think cross fence spillage remains a viable explanation for two flameouts in much quicker succession than expected.

Art of flight 9th Mar 2014 10:54

I think there's the possibility of taking a theory so far that the basic evidence fades until it ceases to be part of it. The engines flamed out due to lack of fuel, that fuel can only come via the supply tanks. We now seem to be jumping to a theory that the supply tanks had fuel in them that then drained back into the main tank after the crash?

So if the supply tanks had fuel in them (with this theory) why did both engines quit?

The evidence shows the xfer pumps switched off, and fuel in the main tank and none in the engine supply tanks. Certainly seems the logical way to eventually starve the engines of fuel.

falcon900 9th Mar 2014 11:48

You are right Art, the drain down into the main tanks is a blind alley.
Lateral spillage in flight, and its potential consequences still has to be dismissed though.

SASless 9th Mar 2014 12:47


The evidence shows the xfer pumps switched off, and fuel in the main tank and none in the engine supply tanks. Certainly seems the logical way to eventually starve the engines of fuel.
Art,

Since when has "Evidence" driven a "logical" discussion in this thread of late?

You are entirely correct in your statement!

The question is "Why were both Transfer Pumps Off?".

Followed by...."Why did the Pilot and Crew not see...or saw but did not heed the cautions, warnings, and Supply Tanks emptying of fuel?"

With the final question of "Whey was the Pilot unable to carry out a successful EOL after the last engine flamed out?".

Art of flight 9th Mar 2014 15:59

SASless

Agreed.

sycamore 9th Mar 2014 17:02

SAS, dual hydraulic failure....

SASless 9th Mar 2014 17:23

Nope....has nothing to do with the evidence noted so far.

Explain the connection between the empty Supply Tanks, the Transfer Pumps being Off....and fuel remaining in the Main Tank.....to a dual hydraulics failure and if you can show a link.....I will listen but not until then.

SilsoeSid 9th Mar 2014 22:20

The final position looks to be at quite an angle;

http://images.dailystar-uk.co.uk/dyn...620x/54510.jpg

Looking at figure3 of RVDT's earlier post, the line that points to the 'overflow', is the 'level' at 75 degrees nose down. I would suggest that the picture above showing the ac in situ shows an attitude greater than that, with the ac leaning slightly to the starboard side.

Looking at figure 1 perhaps it is possible that the fuel was able to drain back into the main through the overflows. (print out, protactor and pencil helps)


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