As I've said, I never used to turn them off, mainly because I never took the caption as indicating a pump failure, and knowing that the caption would go out in a few minutes when I changed the aircraft attitude. I believe that is another Police pilot on here who did the same.

Can't recall hearing of a run dry time for the pumps though.

Sorry, not a pilot, ignore me if you wish.

I have followed most of the pages in this thread and cannot recall seeing any reference to cockpit air processing. Presumably the outside air (5 deg C) is heated to a more comfortable temperature and brought into the cockpit. May I ask what the exchange rate is and what controls are available?

Many thanks.

if he had ~2.5 minutes on one engine after the first flamed out, and was still at 1,000 feet, what are the scenarios?

is it possible to put it down in that time?

Just like the Mull crash, we won't know why the pilot(s) had "apparently acted in a way which was contrary to their instinct and training".

1.4.24
http://www.mullofkintyrereview.org.u...w%20Report.pdf

Forgive me for asking a simple question but it is one that is troubling me. The EC135 has a fairly complex fuel system, that is apparent. But the A/C has been in service now for about 10 years with little or no evidence of similar occurences.
But the EC135 is one of the most prolific of emergency service aircraft in the world today. However, it does seem to me that the vast majority of those missions are of relatively short duration 30-45 minutes or so.
Suddenly with the merging of all Scottish Forces into one the machine is covering a much larger area and mission times possibly significantly extended.

So was this pilot now suddenly faced with a fuel management situation unlike anything previously experienced?

As I said sorry to ask a simple question, but there has to be a reason for some of the unexplained issues.
tigerfish

Impact strength & one-engine time & better landing sites

Doesn't look like it fell from 1000ft? I didn't think so either, but the rarely-photographed bottom of the wreckage, visible when it was craned out of the pub, looked a lot less intact than the much-photographed top.

The terminal velocity of the machine with that drag is also a lot less than something "free-fall"ing. Even stationery blades would tend to make it shuttlecock skids down, presenting a relatively larger area to the air.

It's not clear how long one engine was still running. "A short time" in the report doesn't imply as much as 2.5 minutes, but the timing information available is poor.

As to better landing sites, SASless: there are the gardens of the Peoples' Palace only 600m east of the pub. After that, until the Heliport 3km further across the city center, there's only the river.

Looking at the pic in post #2140, it is not unusual to burn the whole fuel of the maintank and also the switching of the XFER pumps was a common and known procedure for the NPAS pilots, or am I wrong?

skadi

Some really thought provoking posts recently, the last 4 or 5 pages should really have informed all of the fuel system and it's display and caution/warning systems. Hats off to Sid for explaining and illustrating the CAD and the Warning panel. In my opinion it should now be clear to all that if the systems worked as advertised and the CAD was in fact working, the pilot would have and should have taken decisions to land well before the fuel configuration got to the point the AAIB have found.

That really does leave only 2 possibilities, display/warning system faults, or HF, it will be critical that the AAIB find out what this display fault was and if the sensors where contaminated. Once that is known it could be time to move on to the HF.

If it all worked perfectly the chain of events would be as follows.

Ac departs with 400kg fuel with transfer pumps both ON.

Fuel system transfers from main to supplies keeping them full.

Main tank contents reduce to a point where transfer pump cautions appear according to fuel level and aircraft attitude, in accordance with the RFM the pilot will carry out switch position changes.

The main tank fuel contents reduce to empty. The Full supply tanks then start to reduce.

The Supply contents reduce to the point where the amber low cautions and master caution and beep occur, 2 occurences.

The supply tank contents continue to reduce to the point where the Red Fuel Warnings on the Warning panel illuminate with audible gongs and the master caution illuminates, again 2 occurences.

Around 8 to 10 minutes later the first engine flames out. The master caution illuminates along with many other cautions, the police role equipment high power consumers fail. The role equipment screens, camera etc.

Around 2 minutes later the last engine flames out. Many services are lost, many warnings, both visual and audible. The battery becomes the only source of electrical power.

The low rotor audio warning sounds, and warning illuminates if Nr drops below the set parameter. The Nr continues to drop, the hydraulics cease to function and the flight controls become immobile.

This sounds stark, but is a factual timeline/sequence of how the aircraft COULD end up in uncontrolled freefall if NO faults have occurred and the pilot took no action at all other than the transfer pump switch manipulation whils the main tank fuel reduced.

SKadi,

Not just NPAS pilots, it's in the RFM, All pilots operating the 135.

TF,

Npas is flying further and longer with less aircraft. Fuel or lack of it particularly at night (airfields shut and MLA is higher) is at the forefront of pilots minds. In Essex we often would be tasked until we really had to land on minimums.

AoF, if I read the report correctly, when the aircraft crashed there was sufficient fuel in the tanks to keep the engines running and nothing the AAIB could find to prevent that fuel reaching the engines. Yet the engines flamed out through lack of fuel.
The report states:

Quote:
This bizarre and irrational politically (in)correct fanaticism to refuse to accept any possible fault in a dead driver is simply dishonest. It may not be palatable but we know that the vast majority of accidents are caused by human factors, and trying to absolve the humans by inventing the most ludicrously unlikely excused for their accident does them no honour. Just let it be accepted that even the nicest bloke, the finest pilot, the best buddy can screw up. I can. You can. Why can't they? Why is it such a problem to accept that the dead could have made a mistake?

I lived in the little village south of Glasgow where DT lived as well. And my office in Glasgow was just a half mile away from the crash site. However many people have been much closer to this accident. For me things happened are difficult to believe they are real.
It is always a shock when the best of the best encounter what we do not want to believe and perhaps try not to accept.


The quote above is most true and reasonable, a lot more 'professional' than some of the very experienced pilots here who seem to be in some sort of shell shock and clearly unable to deal with a very inconvenient truth. And, FAO John, one doesn't need to be a helicopter pilot or even a professional pilot to understand human failures in stress. Pilots are no aliens, in stress they react quite similar as all other humans. Lots of evidence around.


talking ar's and flare: I feel one should never get in the situation to have two flamed out engines right over a city centre, they didn't flame out at the same time and apparently red low fuel warnings were on. It does not look good but I would agree with TR that the pilot needs a good defence.
This society likes to jump on what seems to be an easy victim, just to make some money - or cover their very own faults -makesmetink abut some prof's here ..


rp

re: pilot incapacitation...could a laser flash have been geatly exacerbated by wearing NVGs? I have been unable to source anything reliable on the web.

Just a thought, suppose the pilot had been flying on night vision goggles (NVGs), and in the course of the urgent actions to diagnose the fuel issue, take appropriate actions and enter autorotation, he had dislodged the NVGs or otherwise caused them to stop working. Could this have caused him to midjudge the height to flare, or realise much too late that his first choice of landing area was unsuitable?

Maybe a regular NVG user could comment on how long it takes to regain vision at low level when coming off goggles?

Absolutely, and the reassessing of bingo fuels during a 'deployment' is becoming more common. It has been known to ask ATC to confirm the opening times of a distant airfield in order to give an inflight decision on deploying to a job.
As for those 4 o'clock in the morning deployments!!!!!


Shaggy Sheep Driver;
… apart from the transfer pumps being off and supply tanks being empty :roll eyes:

Actual flying time was about the same as declared endurance. Is it possible that the transfer pumps were switched off because the pilot believed them to be running dry in an empty tank, whilst looking at a false main tank contents of
0 kg?

OK, something went wrong, first engine flamed out, second engine flamed out. That leaves plenty of time to enter autorotation. So why wasn't it done, (or if it was, why did the pilot flare much, much too early)?

Have the AAIB checked for pilot incapacitation, or included any kind of pathology or toxicology report on the pilot? And if not, then why not?

It seems to me that - after 109 pages - those are the main questions left.

Triskele

It is important to appreciate NVGs are not 'optical' devices, in as much as, light does not pass through them. They are totally solid. It's like looking at a miniature tv screen right in front of your eyes. So whilst a laser attack in that city is far from unusual, the wearing of NVGs is unlikely to exacerbate such an act.

Mechta

It takes a while to readjust to non NVG flight after removing them. Precise period is difficult to determine.

SilsoeSid

I see in your post #2158 you have simply highlighted a passage describing how the only two people to have reviewed the Mull accident, and found the pilots guilty of anything, were utterly unable to explain their own discredited theory. Thanks for the support!:ok:

ZeBedie
a. Take off with 400kgs @ 20:45; End of flight with 76kgs @ 22:22
b. The 'endurance' would be 2 hours, actual flying time was 1:32.
c. The remaining 76kgs remaining fuel should have given around 20 mins more flying time.
d. Fuel burn rate throughout the flight seems to be correct.
e.Transfer pumps would normally have been turned off after a caution, not because 'the pilot believed…'
f. There have been no problems (so far found) with the main tank sensors/probes.

Tandemrotor, please link me to a Mull report that I can quote from, that would be acceptable to you.