[AlanHo]

Jamie might be interested in this

BBC News - Clutha crash: Police helicopter engines 'flamed out'

[FatBoy]

Thanks Alan.

Curiouser and curiouser.  As the report said, the engines "flamed out", but that doesn't explain why the rotors weren't turning when it hit the top of the pub.  76 kg of fuel should be enough to keep the engines running, but if the fuel system is the same in this aircraft as in the BK117 (which it is based on) then there is only fuel in the "supply tanks".  That should give about 20 minutes of "usable" fuel remaining.

It is extremely unlikely that an aircraft will have a dual engine failure, although all multi-engine helicopter pilots practice for that event.  Unless the failure of one engine put an unusually high load on the remaining engine, causing it to fail too.  Again, pilots practice "single engine failure" regularly.  There are even performance calculations / graphs for OEI (One Engine Inoperative).

I don't like the statement by the lawyer at the end of the article about "no emergency radio call".  That is the last thing on your mind during an emergency.  All military pilots in the Western World (and the pilot was ex-Military) are taught the following priorities during an emergency.  Alan's son would have something similar (although maybe worded differently) with BA. 

1. Aviate
2. Navigate
3. Communicate
4. (in Australia) Administrate

So, in essence, fly the aircraft first and foremost; then work out where you are going; then tell somebody about it; finally complete any checklist items that may be needed.  He may not have had time to do step 3.

[Phil №❶]

Dual engine failure without a cause on investigation is certainly very perplexing. If the pumps & switches were configured correctly, then that just leaves the fuel itself, was it fuel.    Given the fire and subsequent drenching to put it out, how can we tell what was in the combustion chambers. I think the statement about rotors not turning is perhaps misreported. Turning and actually delivering power are two very different things. I'm no expert, but it takes some time for the rotors to actually stop turning after engine shutdown, certainly longer than the fall from the sky would have taken. 

[FatBoy]

Sorry Phil, but the rotors were not turning or rotating at the time of impact, so it was not misreported. 

From the AAIB:

Examination at the accident site and further more detailed examinations at the AAIB facility in Farnborough have shown no evidence that the transmission system, main rotor, Fenestron tail rotor and associated drive shafts were rotating when the aircraft struck the roof of the building.

If the pilot mishandles the emergency, or there is some other force, then the rotors will stop, and quickly.  That is why a pilot must enter autorotation to maintain rotor speed.  There was no post impact fire from the aircraft, as can be seen from the photos.

It also appears that while the main tank had 76 kg of fuel, the supply tanks were almost empty (0.4kg) and empty.  The supply tanks do supply fuel to the engines, not the main tank (the main tank supplies fuel to the supply tank via transfer pumps).  All pumps were deemed to be operational at the time of the accident (operational, not necessarily operating).

Here is what the AAIB said about the fuel switches:

The fuel pump switches were examined at the accident site and it was found that the No 1 and No 2 prime pump switches (pRIMe I and II) were set to the on position and the fore and aft transfer pump (XFeR F and A) switches were set to the oFF position.

Here is a link to the AAIB report:

http://www.aaib.gov.uk/cms_resources.cfm?file=/AAIB%20S2-2014%20G-SPAO.pdf

From a quick look, and my experience with a similar helicopter type, it may be as simple as incorrect switch selection.  Normally, after starting the engines, the prime switches are turned off and the transfer pumps turned on.

[Phil №❶]

No worries Fatboy, I was on theorizing, I know SFA about helihoppers. The U tube ones I've seen crashing all seem to have huge difficulty stopping their rotors.

Thanks for the extra info, Fatboy. 

[Just Rick]

I'm going to take the conspiracy theorist option here,doesn't matter what happened,it was a government aircraft, it will all be covered up,swept under the carpet eventually so the government is not left footing a hefty compensation bill.