Depends a lot on where it is. As I understand it (possibly incorrectly), there are three tanks, one main and two subsidiary supply tanks (one for each engine). If something went wrong with the transfer pump system maybe fuel failed to reach the supply tanks. This could be bollocks of course but it is a lot more complicated than a simple car style single tank.
Tim
Well said John. As usual the usual mass of ill informed theories based on incomplete "facts" that are the product of incomplete, or inaccurate, reporting or just plain ignorance.
The AAIB have not said *anything* about the turbines being stationary.
You're talking c*ck again harry. There was 95 litres left on board when it went down. So fuel shortage and/or indicator lights are not an issue.
Yes obviously, what what does this have to do with anything?
AIUI this helicopter had three tanks: a big 'main' one that fed two smaller 'supply' tanks each of which feeds one engine. Internal channels allow fuel flow between the main tank and the supply tanks. One of the latter has a plastic insert in it to reduce the volume, so that one engine will run out of fuel about six minutes before the other.
Depending on the attitude and speed of the aircraft, in some circumstances fuel does not flow along the internal channels to the supply tanks. However, these have indicator lights, amber to warn of low fuel and red to warn of an imminent no-fuel condition. The amber warning is quite normal in ordinary flight, and the pilot's manual carries routine instructions about activating transfer pumps to move fuel from the main tank to the supply tanks, one pump for each tank.
It's my view that there were one or more failures in the fuel-indicating system, that led in some manner to the engines stopping with the result we all know. Unexplained popping noises heard on the ground might indicate one engine being restarted, for example following a sudden red 'no fuel' indication and flame-out of one engine, combined with another failure in the second supply tank warning system together meaning that the second engine then also failed. The number of gauge and light malfunctions that have been found in the fleet suggest that a double failure is more likely than might have been previously thought.
Surely that 'depending' means that in some fairly extreme maneuvering there can be problems. But has anyone suggested that this helicopter was doing anything more than just pootling around the sky?
Because there was no fuel and the pilot thought there was?
[snip]
It appears to be a main tank which evidently had 95L in it and a secondary supply tank split in two that supplies the engines and is arranged so that (in theory) one engine should run out of fuel first.
Bottom rhs of p11.
So it is entirely possible for there to be fuel aplenty in the main tank and nothing at all in the engine supply tanks (although there is still the problem of why the engines didn't fail gracefully one at a time).
Just explaining the fault to a poster who didn't know what it was.
Slightly more relevabt than a rant about the pilot allegedly (TM Private Eye) not dipping the tank before takeof.
A lack of damage to the engines rather suggests that they weren't turning at any great speed at the time of impact. It also rules out bird strike or any other material ingress into the engines.
It doesn't actually rule out bird strike. Small birds could induce compressor stall without causing any obvious engine damage. However, the time of night does make bird strike unlikely as most would have been roosting then.
Colin Bignell
My understanding, which isn't complete, suggests that the amber warning of low fuel can occur when in the hover or the forward speed is
They don't pick up from the very bottom but a little above it to reduce the amount of muck reaching the filter. If you do run a car to a standstill there will still be fuel in the tank, possibly half a gallon or more. Diesels have water traps as water sinks in diesel and water getting into the tank is more likely than just muck.
That depends on how much s**te is in the tank. Anyway in the case of the EC135 everything from the supply tanks on is duplicated.
Oh I *see*. You mean the pilot was colour-blind? So when the light flashed from green to red, he thought it was going from red to green. That probably made him happy - especially to be a pioneer of in-flight refuelling for helicopters.
Exactly. The pickup level never varies. If the muck's below the level when it's full, it's below the level when it runs out.
Yep. Whether it's full or near-dry, since it picks up in the same place.
So that's another half-arsed theory shot down, then...
But that does not explain why there was fuel left yet the engine was stopped. What I cannot get my head around is how the rotors were stopped, inertia should have meant they ware still rotating even if not powered. Are we absolutely sure the chopper was not a lot higher than we thought?
From the people I've talked to, the effects noted would need a higher altitude and a complete loss of electrical power without warning to create the effect seen. Brian
Not a lot of fuel, so slosh could easily starve the engine, but still see my previous point. Brian
Maybe it was bats then. However I really think many things in this scenario do not actually look right. the stationary blades being the main problem. You cannot just stop the blades in a few seconds, its not going to happen, so why no mayday? Catastrophic powe failure?
Brrian
IF the engines stopped AND the collective was not adjusted for autorotate THEN the blades will eventually stop.
And do the shot duck thing.
Someone mentioned that the impact velocity was about 30mph., That's a lot less than 'fall from height with no autorotate'
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