Nor does it say if any fuel was lost as a result of the (very heavy) impact and if there was damage to the tanks due to such....so any fuel related hypothesis is pure speculation.

135 Fuel
 

S/N 250 and up should have 49kg in the LH Supply Tank and 44.5kg in the RH Supply Tank - the Main tank transfer pumps will keep that amount in the supply tanks until it is empty.

This would indicate that the main tank was empty and the supply tanks were being depleted to keep the engines running.

Prolonged hovering can also result in up to 71kg unusable fuel in the main tank. The quantity of unusable fuel can be reduced to 7.5 kg when flying with 80 KIAS or more.

The report suggests the flight was started with 400kgs of fuel. The AAIB drained 74kgs, so 326 kgs used in a little over 1.5 hours? I'm no helicopter expert but this seems excessive.

The engines are self-feeding by engine driven pump that 'sucks' from the supply tanks once the engine is self-sustaining

Yakker, you're right, you are not. Police helicopters hover a lot. That uses lots of fuel.

staplefordheli

Sorry stapes, I cant see that anywhere.
Have you based your statement on the wording;

"Initial assessment provided no evidence of major mechanical disruption of either engine and indicated that the main rotor gearbox was capable of providing drive from the No 2 engine power turbine to the main rotor and to the fenestron drive shaft."


In reference to the fuel load;
"Once removed from the building, approximately 95 litres of fuel were drained from the fuel tank system.
Plenty to have made it back, however the total quantity at the time is till not clear. If you think about the angle of the ac when the fuel was taken, I would suggest that if they were using the forward main tank drain hole, there could be up to 59kg still in the main tank and a few more in each of the supply tanks. They may have been low on fuel, but possibly not below minimums.

[edit] Missed the fact that the post #83 I was referring to is in an old thread from 2004. Ooops!

Looking at that post #83 here http://www.pprune.org/rotorheads/189945-ec135-5.html again, the comment in there about 71kg unusable fuel reducing to 7.5kg above 80kts caught my eye. Does that mean that in decelerating below 80kts that any such fuel becomes unusable again?

Also, post #83 says "When operating at different speeds with low fuel quantity between hover and cruise the FUEL PUMP lights will come on and off which is normal and also depends on the location of the C of G." So, with fuel quantity captions illuminating and going out as part of expected behaviour does that mean that a pilot could be tricked into thinking that any warnings are transient when in fact they are alerting him to a fuel state that requires more careful management?

av consumption is circa 200kg/h

Sid

Not sure what you mean by the angle of the aircraft when fuel was taken.

It was taken after the helo was removed from the building, so probably substantially level.

How far was there to go to the helipad, and at what distance would one expects t to commence a speed reducing flare?

Edit to correct this infernal kindle spell corrector

How far was there to go to the helipad, ?

About a mile and a half due west along the river.

If the rear Fuel Transfer Pump has failed, yes.

Mayday
 

Ref earlier Post from RVDT
Never worked with Dave T but met him thro training role, delightful chap, RIP and condolences to all affected.
Never heard of NIP as an acronym in the rotary world. In my experience real emergencies rarely follow the POH/FRC/Checks etc, and Aviate, Navigate, Communicate is always the mindset I was taught and now teach.
Chinook HC1 in late 80s, flying simple transit with first tourist co-pilot also called Dave who was handling pilot (HP) at time. Gen 1 caption illuminates, " Captain to Crew Gen 1 caption" "Dave you fly I'll get the cards out" FRCs just opening to the correct page when "we have a Hyd 1 caption as well" "now an AFCS 1 caption" "okay some nasty **** is about to happen - I have control - let's put this sucker on the deck now" To my delight Dave starts a Mayday Call unprompted. He surprises me, as at the time I thought a Pan Call would have been appropriate but hey let him handle the radio while I fly it the last few hundred feet into the flare and landing. As we flare the crewman shouts that he has Hydraulic Vapour spreading throughout rear of the aircraft and he is moving the few passengers we have on-board forward to avoid the danger. Successful landing in cropped field and rapid shutdown without starting the APU and everyone clambers out. Not sure of the timeframe but less than 90 secs perhaps. Point is: we didn't know what was going on with multiple indications but we flew the aircraft first and when Dave had nothing else he could contribute he put out a call. The problem turned out to be a Generator cable chaffing a Hydraulic pipe then "bang" the cable earthed and blew a hole in the hyd pipe. No fire down the back but I believe there was a similar incident after I left the squadron where a flash fire did occur. The mayday call by the way roused a Royal Flight Wessex to our aid as the first response - never did find out if there was a principle passenger on-board - but thanks Ma'am or Sir, we appreciated the response.
Things happen very quickly in some cases and flying the aircraft always comes first.
Klingonbc
(Added after below: "Kintyred - good to hear from you")

Happy Days klingonbc.....I was that co- pilot!

That fuel burn is not excessive, it sounds about spot on. Allow approx 200 kg/hr, a bit for start/take off, waiting for cops to come out and it was 1:37 airborne.

Thanks for that, I thought it might. I note that the AAIB stated that the 95 litres drained was from the "fuel system".

Confused by the reference to ATC1 and ATC2? Transponder? Which is what these CB's are on a 135. Most only have ATC2 with one transponder.

IF you lose SHED BUS and subsequently Avionics Shed you will NOT lose either of your Garmins or your Transponder for that matter (ATC2).

These are on the AVIONICS ESSENTIAL BUS.

Avionic Shed Bus 1 & 2 will have the likes of ANR, TAC, GSM, RAD ALT, MKR, DME etc etc.

Simple Test - walk out to your EC135 - BAT ON - Avionic Master 1 & 2 ON.

Tell us what you see because that is what you will get. :ugh:

No, but it does say:

And which is certainly food for thought.

DV8T - re: comms
 

On the police setup, the comms head has a wheel from which you can select atc1, atc2 or any of the police radios (tac1-9) for transmitting. The two front heads can transmit on atc1 or atc2 (air traffic comms),
Whereas the rear observer station can only transmit on tac (police) channels. They can however monitor air traffic in the back.

This prevents observers from accidentally transmitting to atc from the rear. I believe atc1 and 2 are actually 1 radio behind the dash. I'm not a pilot so I could be wrong about the hardware setup, nor can I assist re the transponder

Fuel starvation or another cause of double engine failure does not explain zero rotation of the rotor system. Even if the aircraft was so deep in the avoid curve that an autoration could not be successful, I would still expect to see rotation.

The surreal bit is the rotors not turning.

The reportedly undamaged engines stop, the gearbox is fine, and the rotors stop.

It looks as if the helicopter came down almost vertically with the fuselage more or less pitch-neutral.

Where was the collective during the descent? And why?