Police helicopter crashes onto Glasgow pub

[Heathrow Harry]

"A spokesman for Eurocopter said tests by Bond and two other EC 135 operators in Europe found possible similar supply-tank fuel gauging errors that overestimated the fuel on board.

The first analysis shows that the indication of the fuel quantity in the supply tanks could be overestimated," the company said in a statement.


All crews should be aware that in the worst case a red warning "Low Fuel" could appear without any amber FUEL Caution before."


Possible they got a (wrong) red light when in a difficult position and it acted as a major distraction..................

[HLCPTR]

If I were asked to speculate on this unfortunate event based on what we (think) we know now with respect to this potential fuel indication issue, I would propose the following:

- In cruise flight
- Fuel level OK, no fuel low indications
- One engine flames out due to fuel starvation
- Pilot reacts to engine failure (immediate steps, secure engine, etc)
- Pilot also tries to assess why engine quit with no warning
- Perhaps even attempts at restart
- Left hand busy doing due diligence cockpit duties related to above
- Second engine then also quits with no warning (still no fuel warning lights)

Such a scenario certainly could explain why a fully competent and contientious pilot might be so distracted that he might be unable to effectively (promptly) respond to dual engine failure. Losing both would not be at the top of my "what could possibly happen today?" list.

Until the investigation is complete and the various switch/valve/engine/gearbox/sensor conditions are known, it's only speculation, but I do strongly suspect the pilot had to be faced with multiple contradictory conditions/indications.

[skadi]

If I were asked to speculate on this unfortunate event based on what we (think) we know now with respect to this potential fuel indication issue, I would propose the following:

- In cruise flight
- Fuel level OK, no fuel low indications
- One engine flames out due to fuel starvation
- Pilot reacts to engine failure (immediate steps, secure engine, etc)
- Pilot also tries to assess why engine quit with no warning
- Perhaps even attempts at restart
- Left hand busy doing due diligence cockpit duties related to above
- Second engine then also quits with no warning (still no fuel warning lights)

Such a scenario certainly could explain why a fully competent and contientious pilot might be so distracted that he might be unable to effectively (promptly) respond to dual engine failure. Losing both would not be at the top of my "what could possibly happen today?" list.

Until the investigation is complete and the various switch/valve/engine/gearbox/sensor conditions are known, it's only speculation, but I do strongly suspect the pilot had to be faced with multiple contradictory conditions/indications.

You overlooked a major subject with your proposals: The red FUEL LOW warninglight is independant from the fuel indication and the yellow FUEL cautionlight, therefore youre #2 is wrong.

skadi

[G0ULI]

Further to all the above going on, I have a horrible suspicion that all the panel instruments failed or became unreliable at the same time as the second engine failed due the battery being depleted by relight attempts. That would certainly explain why an experienced pilot might stall the main rotor.

[airpolice]

And.... both of you are overlooking the experience of this crew, in this airframe, on this tasking with the fuel level they had when they left base.

It's not all about the gauges.

I don't believe that they ran out of useable fuel, as they never have before.

[hillberg]

or he knew it was low But the base was only a minute away. Opps.

[HLCPTR]

You overlooked a major subject with your proposals: The red FUEL LOW warning light is independant from the fuel indication and the yellow FUEL caution light, therefore youre #2 is wrong.

I did not overlook it. I suggest that my speculation of no fuel warning is no more speculative than your absolute statement of my "error".

The extent of the fuel indication issue has yet to be fully explained or defined.

[EPAC]

I think the extent of the fuel indication issue has been fully explained by a few people on this site. The issue is with regards to INDICATION, not LOW LEVEL WARNING. They are different systems, its designed that way for a very good reason, they have to be to afford a second, even third, level of warning to the pilot of his fuel status

[SASless]

I have a horrible suspicion that all the panel instruments failed or became unreliable at the same time as the second engine failed due the battery being depleted by relight attempts.

If one engine is running....generator ON.....tell me about draining the Battery again please?

How you propose that would happen?

How many Engine Re-Start Attempts would it take to drain the Battery with a Generator running?

Seems a bit of a stretch.....but around here some very long arms have been seen of late.

[chopjock]

What happens to the hydraulics on a 135 when both engines inop?
Aircraft still controllable?

[G0ULI]

Without access to the wiring diagrams, or knowledge of what systems are fed by each generator bus, I haven't got a clue. I merely mention this as a possibility. In the absence of reliable flight instrument readings controlled flight would be very difficult at night. While the flight instrument panel may run from the battery supply, it might also take several seconds to switch over in event of sudden generator failure. This is all pure speculation, but it would account for loss of control by an experienced pilot and point the finger of suspicion at purely technical causes for the crash and not any human failings.

[Torquetalk]

Seems a bit of a stretch.....but around here some very long arms have been seen of late.

and it was a police helicopter.


chopjock,

The hydraulics work when the rotor turns, powered or unpowered.

[EPAC]

The hydraulics are gearbox driven. In flight they provide 103 bar. The hydraulics stop being useful at 69 bar

[nigelh]

I believe the hydraulics would continue to work as they do with the AS350.
No . Restarts would not drain the battery !!
I don't think it's possible that the blades stopped any higher than say 50ft , if that . There would have been nothing left , just a big crater . It must have entered an autorotation of sorts from 700ft to 50ft or so . I think it is possible the pilot may have used the brake after impact . A few seconds later the roof collapses .

[Lonewolf_50]

Not familiar with EC-135.
In the helicopters I flew early on Nr on the triple tack was powered by an old fashioned thing call a tach-generator. Maybe this tech is too old to use anymore. In those machies, with all electricity off, you'd have the triple tach, and all of the old steam A/S, VSI, and BarAlt working (but maybe need flashlight to see them if it's at night.)

Has the move to more digitial cockpits sent the Nr tach generator the way of the plains buffalo?

With central displays incorporating all display functions, flight and performance, does a loss of generators mean it all goes south? IS that the case in EC135, or does the Nr signal still come through so long as the transmission is turning with the blades? (Granted, Nr indication now does one little good if the head stalls ... )

[jayteeto]

Relight attempts? WTF?
The so called changeover from generator to battery doesn't exist. It's the same Busbar, the gen drops off and the voltage is maintained by the battery.

[Munnyspinner]

Can we dispel the freefall from 1000'? An object weighing say 2450kg falling from 1000' would take around 8 seconds and arrive at 0' at a speed of approximately 80m/s that's around 290km/hour or 180mph. We know the aircraft was in normal flight at around 700' shortly before the impact. It was heading west but ended up to the north of track heading north with no apparent horizontal velocity. Prior to the fall, there was an as yet unexplained sequence of events resulting in apparent loss of power and, at some stage, Nr becoming zero. There is no reported evidence of a major catastrophic mechanical failure. The engines were reported as being capable of delivering power, although it is not reported that they were producing power, and both the maingearbox and TRGB were recorded as being intact and capable of functioning normally prior to impact. I am not quoting the AAIB report verbatim but I believe that these are the general facts. Around 95l of fuel was drained from the aircraft after extraction but it us not clear from which tank(s). A low fuel warning erroneous or accurate in isolation seems unlikely to have precipitated events. However, the absence of a low fuel warning and flame out on one engine may have been the first in a series if events.

[geebee50]

nigelh - thoughts are plausable at that particular point in the flight, others have commented on how relativley undamaged the aircraft appeared, and others have commented primarily from witness accounts who were under the impact point, how there was a noise first, the band commented on it and began to play again, then the roof came in. This is significant in terms of considering the impact speed/force and its immediate effect. I would hope that the AAIB considers reconstructing this part of the roof at a test facility and drop test some weight onto it. They would however have to salvage some of the remaining roof to do so to replicate aged structures etc. There was a considerable amount of roof undamaged and I would assume that much of the various main roof layers were laid at the same time and would provide a benchmark, a better physical fit benchmark than a theory. I only mention this as a avenue for consideration, the AAIB may well have this in mind.

[Back at NH]

He was a mile/mile and a half or so from landing. Why would he attempt a relight? Surely it would have been immediate actions and concentrate on the landing.

If one engine failed, with the different size of the supply tanks giving him another minute or two before number 2 went out, surely he would have spoke to Glasgow (assuming this frequency was still selected)?

Personally, I don't believe he ran out of fuel. The AAIB says MRGB was capable of providing drive to the fenestron drive shaft. I believe that statement may prove to be pertinent. I could very well be wrong, just my personal thoughts.

[Back at NH]

@nigelh/geebee50

From the AAIB report

struck the flat roof of the single story building with a high rate of descent

Very extensive damage and disruption of the helicopter structure

Clear impact distortion of the structure

neither the main rotor nor the fenestron tail rotor were rotating

To me, it plunged straight through the roof and then there were secondary collapses.