Police helicopter crashes onto Glasgow pub: final AAIB report [Archive]

PAX_Britannica

23rd Oct 2015, 12:46

Yes really.

There was ample time to crosscheck the flicking of the right switch. A possible reason not to switch on the XFER pumps but switch on the PRIME pumps is if there is no valid reason to, that is, that 75Kg fuel remaining was presented as 0kg or unusable - which we will never know.

If fuel remaining was presented as 0kg or unusable then MAYDAY ?

Since the helicopter had 76 kg of fuel on board at the time of the accident, the pilot might have been expected to make a PAN call, upgrading it to a MAYDAY on reaching the Final Reserve Fuel IFR [i.e. 85kg], if he was aware of the fuel state. Again, due to the lack of evidence that might otherwise have been provided by cockpit voice and flight data recorders, the investigation was unable to determine the reasons for this apparent omission.

What's the pilot doing snooping round Bargeddie, down to 87kg ?

The FLIR system may have been used during this final task and verbal exchanges probably took place within the helicopter but no evidence was recovered which could explain the reason for the 5 minutes spent in that location or provide any indication of the crew’s awareness of the fuel situation. It was calculated that, as the
helicopter left Bargeddie, a total of 87 kg of fuel remained on board.

While the AAIB has something to say about contributory factors - such as the problematic procedure of activating the SHED BUS switch during autorotation - it seems hard not to say that - for unknown reasons - an apparently experienced and capable pilot was having a very bad day.

Reely340

23rd Oct 2015, 13:19

My vision of possible occurrences after reading the final report:

- both supply tanks did falsly indicated full on the CAD
(a 0.5ml (!) water globule at the capacitance based fuel sensors can do the trick, see p. 54, G-NWEM)

- "Low Fuel" Warnings (driven by correctly functioning thermistors), were considered as acting up "shi**y EC".
The were acknowlegded as being irrelevant, because of (incorrect) triple "plenty fuel" indication on the CAD.
That is the reason why he flew that final task, although he just had acknowledged the Low Fuel warnings, multiple times!

- right engine dies, still with wrong fuel indication of CAD or suddenly correct emtpy indiction
(as the waterglobule was finally gone)

- stress level rises: "damn EC, lets do the OEI drill, we've got at least 4 min to go till trouble"
pilot commences OEI setting checklist, switch check, etc, when

- he was scared by 2nd engine spooling down 32 secs later
coupled with lights out and radalt off, right where he'd never planned to land

That leaves the following:

pilot errors:
- not being aware of sensor reliability differences between CAD tank indication graphics and thermistor driven LOW FUEL warning lights (e.g. low fuel override any CAD fancy graphics)
- botching the autorotation due to high stress when at night his ac goes dark, that was showing sufficient fuel in all three CAD graphics regions, just seconds ago.

It does need some cold heartedness to put the sole blame on him.
His actions do not line up with an +5500h pilot flying with NVG and all, from radio comm (or lack thereof) he appeared very relaxed:
He might have felt to be sitting in an ac acting up with the insider-known unreliable fuel indicators. :rolleyes:
Operators have been sending in "bad fuel sensors" for repair and mostly got them back with "all within sepc".
Therefore he showed no noticable stress on the radio.
Therefore he did the final sortie(?) near Bargeddie, with LOW FUEL warnings, w/o being concerned or feeling negligent.
Checking xfr switches after right engine stopped wouldn#t feel very urgent had the CAD indicated ok supply tanks.

eurocopter error: stupid fuel pumps setup
The fuel system features "a pump runs dry" sensor. Only after the sensor is on for three minutes uninterruptedly the "F PUMP AFT/FWD" warning comes on. AND the warning does come on too, if the pumps are off, but immersed in fuel for three minutes! See p.16
This super manual fuel pump operation regime, coupled with varying fuselage attitude and unergonomic switch placement, presents an engineering wise totally unnecessary work load for the pilot.:ugh:

The Reely recommended setup would be:
Install transfer pump switches featuring three positions: off, auto, on
auto will start the pump after it is immersed in fuel for 10 seconds straight, and will stop the pump after it was "dry" for 10 seconds straight.
Having one of those "reely transfer pump switches" to "OFF" should be indicated on the CDS as red warning text (starvation risk)
Having it on "ON" would be an amber caution text (dry run risk).
And only with the switches on auto there'd be no message.:ok:
The nice part: all you need is already in place: There is a software that controls the warning light. It maintains timers, resets them to 0 when ever the pump gets splashed at from time to time, and only fires the warning light after sustained three minutes of a "dry" or "immersed" condition. All they need is two switches, two relais and a slight amendment of the current transfer pumps monitoring software.:ugh:

That'd preserve the pilot's old style manual (override via off-on) control over the pumps,
and, when set to auto, he could totally forget about transfer pumps mgmt.

Good Business Sense

23rd Oct 2015, 13:38

Would 1:37 airborne not have the pilot in squeaky bum time with respect to fuel availability without the need for fuel indicators and warnings to advise ?

DrinkGirls

23rd Oct 2015, 13:57

One little extra point, if the supply tanks were faulty showing full (my personal theory), the CAD Amber fuel caution does not operate when supply tanks go below 32ish. See NWEM pictures for proof. The board 'found no evidence of CAD fuel illuminating'.
Sadly my good friend ignored a critical warning and continued on task. He must have been misled by the gauges. To say there was no evidence to show a fuel system fault is a poor conclusion. That moves blame from 50:50 pilot:manufacturer to 100% pilot. Sad, but not unexpected

Heathrow Harry

23rd Oct 2015, 15:10

Looks like he switched the pumps off and just forgot to switch them back on - all the warnings he was getting he just fixated as error warnings

"Up to the accident to G-SPAO, the EC135 had accumulated more than three million flying hours, over a period of about 20 years, and there had not previously
been a reported instance of fuel starvation"

there but for the grace of God go ................

maddmatt

23rd Oct 2015, 15:45

How hard is it to judge height above Roof Tops in the Dark?

There are Street Lights and other light sources visible to aid in judging height.

Add that to the definition of angle by looking at building shapes, streets, vehicles (moving and parked)....there is still a lot to see that would aid in determining height.

Somehow I find it hard to accept that the Pilot would misjudge aircraft height by Hundreds of Feet even without a RadAlt or Landing Light being functional.

Actually it can be extremely difficult, ambient light conditions, weather - especially if its raining and cockpit management - ie dealing with low fuel etc.

The roof of that pub, at night and in rain could easily be mistaken for tarmac, unfortunately we will never know for 100% certainty, the facts are that an experienced high time pilot got in to a situation that snow balled very quickly resulting in a serious accident.

We will all have our own opinions but I think it is disingenuous to start portioning blame on the pilot in light of how much is still unknown about the root and subsequent causes. In all likelihood it would have been a chain reaction sequence of events that ultimately caused the crash.

Oldlae

23rd Oct 2015, 15:52

I note that the target date for the development of a low cost FDR is December 2000, Already missed. The main work to install a FDR is the wiring and fitting of sensors, also some instruments may not be compatible. A CVR fit is relatively easier.

skyrangerpro

23rd Oct 2015, 16:04

I thought very little was made of the error in the manufacturers manual regarding the length of time between engine flameouts. Stated as 4 mins, yet even with the supply tank contents as prescribed in ideal conditions, it was nearer 1 min 30, MAX. Manual has now been corrected, but if I had been over a city centre and that close to base, I know how I would have been thinking of using those 4 minutes ... And it doesn't involve an emergency landing in the city centre.

You've nailed it. Sadly this incident was completely avoidable. The sequence of events can be divided into two parts. The events leading up until the moment that the first engine to fail started sucking air, and the events thereafter. We will never know for sure what led the pilot to turn and leave those transfer pumps off in the first stage but bad design that failed to foresee this scenario, ensured that what was a drama became a crisis when the second engine started sucking air just 30 seconds later, exacerbated by the pilot's belief from training that he had 4 minutes breathing space if he had recognised by that point what was going on.

A very good pilot simply ran out of time. 30 seconds is too short a time for the second engine to fail for the same fuel starvation reasons.

The report states:

"Corrective action is being taken by the manufacturer to amend the potential
engine flameout interval to a more accurate figure in the next revision of the
SDS manual, scheduled for publication in December 2015." The manual says that the 4.5kg difference between tanks allows 3-4 minutes between engine flame outs.

It is my belief that give the pilot 3-4 minutes rather than an unexpectedly short 30 seconds and he would have had a very good chance of getting that craft and its occupants down intact.

It is not the manual that needs updating, it is the design that needs changing to increase the differential in tank size, ensuring that the pilot gets his full four minutes. Maybe it is not in the AAIB remit to make this recommendation but it seems an obvious fix and provides a safety net to the same situation developing again.

badger101

23rd Oct 2015, 16:18

Seeing as there were two Police Officers on board there must be a Police Radio Log available that might give a clue?

falcon900

23rd Oct 2015, 16:19

A further thought on the supply tank capacities. We know that the right tank holds 4kg less than the left tank, the idea apparently being to prevent both engines flaming out at the same time due to fuel starvation.
Given that the aircraft would have been flown exclusively from the right hand seat, would there not be a natural tendency for orbits to be flown to the right, as was the case here? In such circumstances, unless the turns are perfectly balanced, there would be a tendency for fuel to cross the tank divide from the tank which was supposed to hold more, to the tank which was supposed to hold less?
For as long as there is sufficient fuel in the main tank to keep the supply tanks topped off, this situation would correct itself, but once you have insufficient fuel to top them off, and/ or the transfer pumps are switched off, there is no way to correct this situation, so all bets should be off as to which engine would flame out first, and how long a gap there would be between flameouts.
Would the situation not be better if the supply tanks were in fact completely separate from each other, giving greater predictability over what their relative contents would be?
The manual said he had 4 minutes from first flame out to get the aircraft on the ground, and it is very hard to imagine the shock when the second engine flamed out so quickly thereafter. The odds against a successful autorotation from that height in those circumstances were always significant; that degree of shock made them overwhelming.
Which does nothing to address the elephant in the room: why does there seem to be no sign of fuel anxiety in any of the pilots actions? Everything in hindsight screams "land" and yet he was taking on additional apparently routine tasking beyond what would seem any point of reason. I must confess to being a little underwhelmed by the report in its lack of exploration of this aspect. We learn that the initial tasking was to do with an incident on a railway, but what were these routine tasks at the key stage of the sortie which seem to have cropped up at such short notice? Could they have affected the pilots judgement, for example relating to a threat to life, sufficient to persuade him to stretch the elastic a bit further?
I appreciate it is not the AAIBs remit or style to speculate, but the report just seems to fall short.

B407

23rd Oct 2015, 16:34

Been following this accident from a great distance for quite awhile. Easy to have missed this, but the question that keeps me thinking about this is, "why did this helicopter depart on the mission with so small a fuel reserve?" It seems that modern technology encourages fuel planning to the last drop. Numerous accidents have shown that this is fraught with peril.

Sky Sports

23rd Oct 2015, 16:34

Reely340
Therefore he did the final sortie(?) near Bargeddie, with LOW FUEL warnings, w/o being concerned or feeling negligent

Please tell me there aren't other pilots out there, who having just done 1:37 in a 135, would do this!! :eek:

capewrath

23rd Oct 2015, 16:45

That is an interesting point.
Hopefully there will now be a Fatal Accident Inquiry (required by law in Scotland when someone is killed at work). The Sheriff will want to know details of any police communications.

Sky Sports

23rd Oct 2015, 16:55

I know the AAIB got a lot of flak for the time it took to publish this report, but given the amount and depth of testing they did on the aircraft systems, it now seems justified.

MightyGem

23rd Oct 2015, 17:12

why did this helicopter depart on the mission with so small a fuel reserve?
It didn't. It departed with the required full reserve, but flew past it.

smc33

23rd Oct 2015, 17:19

Yes if there were any communications between the crew and a Police control then it would be recorded, but obviously there was nothing or it would have mentioned it in the report.

B407

23rd Oct 2015, 17:23

It departed with the required full reserve, but flew past it.

Well ... OK. No matter the size of the reserve, if ones uses it up, one likely arrives in deep stuff. But, does the required reserve anticipate the possibility of stranded fuel due to malfunction or pilot error, or does it assume everything works perfectly? Its been a long time since I read the threads on this accident, but IIRC the required reserve might have been around 10 min. If so, IMHO, cutting it way close, especially if at night in a densely populated area. YMMV.

Sky Sports

23rd Oct 2015, 17:41

The fact the pilot had 20 audio or visual warnings of his low fuel state, prior to engines shutting down, (table 3, page 33), leads me to believe that he thought they were spurious warnings and decided to carry on with taskings.
But even still, would you risk it?

Heathcliff

23rd Oct 2015, 17:44

"Financially catastrophic for BOND."

What an odd and very unpleasant comment. 10 people died. Why would you even start thinking about financial consequences?

If the AAIB have not apportioned blame, I fail to understand why anyone on these boards would wish to, or try to.

Heathcliff

23rd Oct 2015, 17:57

You seem determined to make out the pilot to be some sort of arrogant, thoughtless idiot. The fact that he was none of the above suggests there was a little more going on than thoughtless, idiotic arrogance, the reasons for which we are very unlikely to find out.

the_flying_cop

23rd Oct 2015, 18:02

Had that been my driver, he would have been getting his head pecked to RTB from the moment that first caption went off. I am aware that different units and even crews have a different level of CRM some are less interested in the aircraft side than others.

I still cannot comprehend how this accident actually came about. I just pray it doesn't happen again.

Mechta

23rd Oct 2015, 18:43

With so much emphasis on the position of the fuel pump switches, I hope some tests were done to determine whether a 70g impact would be sufficient for them to move from ON to OFF.

A 70g impact would also shake up the tank contents a good deal, so any water that was in the tank, for instance as droplets on the capacitance fuel probes, would have been washed off and could conceivably have been in suspension in the drained fuel.

capewrath

23rd Oct 2015, 18:51

But the point is that if there were no communications or any communications that took place gave no indication that they had any relevance then that has to be specifically stated and not just left inferrred or assumed.

Pittsextra

23rd Oct 2015, 19:00

I'm sure this report was a very emotional time for all those affected and you have to feel for them given the timescales involved.

With the final report building upon the same themes as the special bulletin published in Feb 2014 what is not very well understood here is 1) why the AAIB couldn't communicate to that effect at the earliest 2) what elements took so long to conclude from the draft final report that was highlighted way back in May 2015. Was that mere process (i.e. draft final to published final always take circa 6 months?) or was there some element of debate?

Rigga

23rd Oct 2015, 20:03

Pitts,
The AAIB research process does not just involve AAIB staff. They need to make appoinments with others and line up any facilites needed - and then react to any potential findings that may lead to more appointments - and then react to.....along the way.
I'm sure the AAIB did a perfectly good job within their rules and practices.

Reely340

23rd Oct 2015, 20:06

I find it weird that apparently noone considered, that on the way back to base G-SPAO's CAD looked exactly like Figure 11, p.53 (G-NWEM during test) of the final report:
a) Both supply tanks indicated as full,
b) the main tank is seen gradually draining,
c) yet the LOW FUEL 1 and LOW FUEL 2 warning light comming on, time and again.

a) + b) are exactly what normally would happen,
when fwd. xfr pump is on, as I'm sure it typically was on other flights.

When presented with such grossly contradicting information
one might easily tend to trust the graphics and
regard them warning "lamps" as faulty.

NR DROOP

23rd Oct 2015, 20:18

... And the lack of an amber "Fuel" on the CAD would add to the confusion.

biscuit74

23rd Oct 2015, 20:21

MightyGem

23rd Oct 2015, 20:21

does it assume everything works perfectly?
Well, yes.
But, does the required reserve anticipate the possibility of stranded fuel due to malfunction or pilot error,
So, how much would you allow for that?

Had that been my driver, he would have been getting his head pecked to RTB from the moment that first caption went off.
I'm sure that mine would be doing the same. However, as I've said to my CRM classes on occasion, "I will kill you because you will let me". :(

I still cannot comprehend how this accident actually came about.
Likewise. This is probably the only accident during my 30 year career that really got to me, because it just seemed so inexplicable. :confused:

B407

23rd Oct 2015, 20:26

So, how much would you allow for that?

Enough. :E Depends on the design of the fuel system. In this case, not clear if the pilot would have ever turned the transfer switches back on. However, an earlier low fuel caution may have allowed a little more time to figure out what was happening.

Good Business Sense

23rd Oct 2015, 20:48

SASless

23rd Oct 2015, 21:49

Biscuit,

Right after this tragedy occurred I asked the question why the Transfer Pumps were switched on and off at various stages of flight in the 135.

I have flown the 105 and 117 and once we turned the Transfer Pumps ON....they stayed ON until the Shutdown Procedure after landing.

Are there any real reason that could not be the policy for the 135?

I accept there might be additional wear on the Pumps over time but as they do have OverTemp protection....is there any absolute need to shut them off?

Had those Pumps been turned on at Engine Start and left on until the After Landing/Shut Down procedure....would that have had any effect upon the outcome of this accident?

RVDT

23rd Oct 2015, 22:34

Not much in the report that was not already known.

Of interest and not mentioned in the report was the point that the aircraft being in the state it was in (double engine failure),
and if there was enough altitude to recover from the problem i.e. turn the transfer pumps back on and initiate a restart,
in a least ROD Autorotation speed of 60 knots, without having the SHED BUS SW in EMER, you would not
be able to get the fuel to transfer as the AFT TRANSFER pump is on the SHED BUS II unless you switched the SHED BUS SW to EMER.

On the point of shed bus logic and use - for me an Ops Manual change to operate at Night or IMC with it in EMER as the norm
could be appropriate.

Moons a go when operating a B205 in remote areas we operated with it in EMER all the time. Reason being - engine failure =
no HF - which was the only means of Comms = SOP.

There is also a hint that the prospect of an engine failure was not prepared for. When the first engine stopped the second
went into OEI limits. Normal prep for an impending engine failure or prior to stopping one intentionally is to reduce power.

The 135 like all other twins (except the single engine derivatives) have low inertia rotors inherent in the design.
I may have mentioned this before but the FADEC is so good it masks this characteristic.
If you have a failure of the remaining engine from high OEI which in this aircraft is plenty then you possibly need to be a bit sharper
than your SE brethren at entry to autorotation.

I have flown the 105 and 117 and once we turned the Transfer Pumps ON....they stayed ON until the Shutdown Procedure after landing.

Are there any real reason that could not be the policy for the 135?

Old style Globe pumps and the characteristics of the tanks in the 135 may be different. New TESTFUCHS pumps are up for it and that was mentioned
in the report as a future change which will require Software, RFM changes and certification.

This accident is hard to fathom and somewhere there is more to it. If all things were operating as normal which they appear
to have been it would have been lit up like a Xmas tree and barking at you.

As to fitting FDR's CVR's etc. It may have helped fathom a few things but possibly not the reasons for them.
I don't think they are as effective in this case as most would believe but agree that they are better than nothing.

skyrangerpro

24th Oct 2015, 00:02

I am intrigued, and somewhat surprised, by the emphasis by some on the Flight Manual information error, in which a stated 3-4 minutes difference in fuel starvation times actually became around 30 seconds.

Surely to reach that point and expect to make use of it is the last desperate hope. I find it hard to believe that anyone views that error as significant in any real flight safety sense - given the quite clear 'land within ten minutes' (after low fuel warning) instruction, also in the FM. I really can't believe that was in any way in the pilot's mind.

I don't really understand the point you are making. I am not suggesting for a moment that it was in the pilot's mind at any time leading up to the first flame out that he could rely on 4 minutes extra time. But once we have reached the point of fuel starvation and first flame out, whatever the reason, it makes no sense to design the relative sizes of the supply tanks so that the second engine is starved after as little as 30 seconds. They should be designed such that the second engine has at least a few minutes fuel under all circumstances, which also allows critical items like radio-alt and search light to continue to be powered. That would at least give the pilot some chance over a built up area in the dark, rather than everything shutting down almost instantaneously.

There is another point that has not been commented on. In the Feb 14th 2014 special bulletin the AAIB stated that both prime pumps were ON. They have now back tracked on that and say on P46:

"There was significant displacement of the cockpit overhead switch panel
which appeared to have been driven downwards on to the upper surface of
the instrument panel coaming. Photographs taken by the first responders
appeared to show at least one of the prime pump switches in the off position.
When examined by the AAIB after the accident site had been stabilised, both
the No 1 and No 2 prime pump switches were found to be in the on position."

Now to me that calls into question the reliability of the assessment of the position of all switches, particularly in the overhead cockpit that has sustained serious damage and potentially been interfered with by untrained first arrivals. It also potentially blows out of the water the gathering consensus that PRIME and TRANSFER switches were mixed up by the pilot.

Take a completely different scenario where the pilot realised at the very last second, perhaps at the moment the first or even second engine flamed out, that he had the transfer switches OFF and switched the transfer switches back to 'ON' but too late to recover the situation and too late to stop the engines flaming out. And suppose when the scene is examined they were indeed found to be ON. Would we ever have known that they were OFF right until the very last moment? Relying on switch positions after a 100G event seems a leap of faith.

G0ULI

24th Oct 2015, 00:20

Well that was a disappointment. Nothing new to be learned, but a great deal of back covering by the manufacturers.

The fuel sensors were not faulty, the compressor washing procedure caused water ingress to the fuel system - operator error.

The overly complicated fuel system was fully functional but the switches were in the wrong position - operator error.

The pilot ignored visual and audible low fuel warnings and departed from SOPs - operator error.

None of the crew reported any issues with the helicopter despite conditions being appropriate for PAN and later MAYDAY calls - operator error.

Auto rotation from a relatively low altitude and speed with a low inertia rotor not completed successfully within two seconds of second engine spooling down - operator error.

Human factors and cockpit gradient not even mentioned in the report other than a description of each crew members role. An interesting omission as it clearly has some bearing on subsequent events.

Even the most reserved of crew members would surely express concern at two low fuel captions illuminated after a fairly lengthy flight rather than accept another quick tasking? Definitely something not right going on. Of course the pilot could point to the main tank quantity as being more than adequate, and they were only a couple of miles from base, but still...

Well Eurocopter are not at fault, so that's the main thing.

PAX_Britannica

24th Oct 2015, 00:40

NTSB reports where human factors are potentially relevant tend to discuss the pilot[s]' activity in the days before the flight: Did they sleep well ? Did they appear to be in a normal emotional state ? Could they have been fatigued by off-duty activities ?
Perhaps the answers are yes,yes, and no - but these are relevant factors, and it would be helpful for the AAIB to report on them in a little more detail.
1.
The pilot was properly licensed and qualified to conduct the flight, and was well rested.

How did other Police Observers regard the pilot ? - They have some role in CRM. What was the authority gradient ?

How did other pilots regard the pilot ? [recent experience, not on Chinook]

What was the motivation for the detour to Bargeddie ? Was it planned / considered in flight planning ? Was it authorised ? What was the significance of the target ? What was the authority gradient ?
I find it unfortunate that the report doesn't seem to comment on Police responses - or lack thereof - to such questions.

On completion, the helicopter appeared to route back towards GCH [Glasgow City Heliport] but, after nearly a minute, it turned from a west-south-westerly track onto a north-easterly track, towards Bargeddie. Once more, no radio transmissions were received from the crew and, without a cockpit voice recording, it is not possible to know what conversations and discussions took place between the crew members, to explain why the task at Bargeddie was undertaken, with the low fuel warnings having been active for at least eight minutes

Without the Bargeddie detour, the aircraft might have made it back to base, even on remaining supply tank fuel, and would perhaps have landed with total remaining fuel exceeding night/IFR reserve - though in a dangerous state..

SASless

24th Oct 2015, 01:05

Sky,

Would we ever have known that they were OFF right until the very last moment? Relying on switch positions after a 100G event seems a leap of faith.

As the switches were next to one another....and they were found in positions opposite of what they should have been in....Prime Switches ON....Transfer Switches OFF....would your 100G event (apparently nose down when that 100G event loaded the Switches) would that cause the Switches to be in the wrong positions?

I have to assume "Forward" is ON....and Aft is OFF.....and unless I am mistaken they are not gated switches....it would seem all four would have been ON if the G Forces of the impact were to have shifted those switches forward.

Cows getting bigger

24th Oct 2015, 07:26

I'm sure that (almost) all of the above is extremely valid and should be considered/implemented in order to minimise risk in the future. However, whatever happened to the relatively basic mental gymnastics that most of us use on a daily basis? My understanding of the extant SOPs was that Night/IFR final reserve was to be 30 minutes, about 85kg. So, the sortie commenced with 315kg of task fuel available which, at the historical burn rate of 3.3kg, gives 95 minutes of flight time.

I'm a bluff old traditionalist and in my world I would have imprinted 95 minutes on my mind before getting airborne. Any fuel warning, especially beyond the 90 minute point, and I would be going straight home.

It is extremely annoying to know that there was actually enough fuel in the aircraft to safely make it home and, for the sake of some (more ergonomically designed) switchery, we would probably have been left reading a GA occurrence bulletin. However, regardless of the technology, there is no escaping the fact that this aircraft was being operated at (beyond?) the limit of the prescribed procedures. :(

..... and before anyone shouts me down, I spend much of my life wondering about how many more minutes on-task-time I've got left in a very thirsty Piper Chieftain.

DrinkGirls

24th Oct 2015, 08:08

I don't think anyone will try to shout you down Mr Cows. I don't think anyone disagrees with the fact that the pilot made some poor decisions. All we are saying is that things are not Black and White here. This man was not a risk taker, if he was airborne at night with empty supply tanks and two red lights on, he would not have gone off to complete that last ROUTINE task. There was no pressure on him.
SOMETHING must have confused him into believing that all was well in the fuel world. Note my wording, confused him. Even with warning lights and captions, he didn't spot his predicament. No evidence in the memory of a FUEL amber CAD caution is the one that keeps raising my alarm bells. That is triggered by the supply tank indications reaching a certain level on the gauges, NOT by a sensor. If the gauges showed permanent full like G-NWEM, that caption would not have illuminated. And it seems that it didn't.
Whilst that is no excuse for not looking at the clock, no excuse for incorrect drills, no excuse for a poor autorotation, it IS a contributing factor (if it happened of course).
However, what is done is done, we can't take it all back. What we CAN do, is make sure this never happens again. This is a problem, because changing components and procedures is seen as indirectly admitting responsibility. That would be financially catastrophic, so don't flame people for talking about money here, it is actually very relevant to the investigation. Everyone is talking about cockpit voice recorders. Great!! That allows us to see why it happened, but it STILL WOULD HAVE HAPPENED. That leaves education, every new EC135 pilot gets better teaching right now, but in 5 years time, this will be a distant memory. The fact that nothing in the aircraft has changed means that all the holes could line up again.....................

CJ Romeo

24th Oct 2015, 08:55

As a local, I have took a bit of interest in this, and from the start it has nagged at me that if the pilot knew there was a serious problem, why did he overfly a flat park when it could have landed, been easily secured and refuelled, it is only a few hundred yards east of the crash site.

Although not an aviator, I am an engineering designer so understand the fuel system having read through the report and old thread in here.

What is not clear to me, and that you pilots of these machines may know, is that is it really that difficult to establish that one turbine has flamed out, the report seems to indicate that the annunciation are not that clear (might just be me).

A FAI has been mooted politically, it's not hard to see where this will look:

1) The report is silent on why Police Scotland set the tasks to the crew.
2) Is airwave not recorded?, so little on this or the traffic in there.
3) Have other duty pilots assigned to police Scotland been interviewed regarding pressure to fly longer missions than are comfortable and perhaps a culture of exceeding fuel minima's?

Police Scotland are in real trouble, having let two people die by the side of the road and also killed a man during breach of the peace arrest, the chief constable has resigned, and of course the amalgamation of the Scots forces is a political decision.

Surely the Police must assess the risk of putting air support into situations instead of just tasking all sorts and leaving it to the pilot.

I fear scapegoating here, after the farce of the other Glasgow FAI where another vehicle in public service killed members of the public, but from the outset it was clear that the Council were never going to get sanctioned.

Finally,on the engineering, a system I designed that almost killed people when mis-managed by the operator. Several experts criticised the complexity of the system, yet each one had recommendations that made it even more complicated to operate. I must say that I wouldn't from an engineering perspective like to rely on sensors to stop and start overheating/dry pumps from and always on perspective, and if they operated automatically on level sensors, my personal belief is that this would be prone to malfunction.

The bus coupler device to operate the essential instruments does seem ridiculous in this instance, not having this in an accessible location in a single pilot operation. I would have thought (and I don't know if aviation permits the approach) that essential instruments circuits automatically transfer and let the circuit breakers do their job in case it's the instrument circuit itself that's faulty.

Very sad situation all round.

Reely340

24th Oct 2015, 08:58

SASless: I have flown the 105 and 117 and once we turned the Transfer Pumps ON....they stayed ON until the Shutdown Procedure after landing.

Are there any real reason that could not be the policy for the 135?
Depends if you view the AFM as real reason :E
(p. 3 - 26):
.F PUMP FWD
(MISC)
Conditions/Indications
Failure of forward fuel transfer pump, or dry run.
Procedure
1. Fuel level in the main tank – Check
If main tank fuel quantity is sufficient to keep both fuel pumps wet:
2. FUEL PUMP XFER-F sw – Check ON
3. XFER-F PUMP circuit breaker – Check in
If F PUMP FWD indication remains on:
4. FUEL PUMP XFER-F sw – OFF
If main tank fuel quantity is low:
2. FUEL PUMP XFER-F sw OFF
NOTE Each fuel transfer pump is capable of feeding more fuel than both engines will
consume. In forward flight conditions the unusable fuel can be up to 59 kg. The quantity
of unusable fuel can be reduced to 3.6 kg when flying with 80 KIAS or less.

Firend of mine is flying HEMS in EC135 and confirmend that one has to switch between XFER-F ON and XFER-A ON between cruise and hover, IF you did not gass her up fully, because you were anticipating you have to climb to high places to rescue someone.

I accept there might be additional wear on the Pumps over time but as they do have OverTemp protection....is there any absolute need to shut them off?

Had those Pumps been turned on at Engine Start and left on until the After Landing/Shut Down procedure....would that have had any effect upon the outcome of this accident? If they were oscillating between "hover" attitude (< XX kts) and cruise flight maybe the run dry lamp would not have come on...
IIRC the was a statement in the report that them pumps can survive 20min of running dry. Didn't sound as if ignoring dry running were a professional/safe thing to do.

edit: I've got to talk to said friend, as he is FI on BO105, too.

Never Fretter

24th Oct 2015, 09:51

This is not the first double engine flameout over a city
Fatal Japanese Police AW109 accident (http://aerossurance.com/?p=1260)

Reely340

24th Oct 2015, 10:53

skyrangerpro (http://www.pprune.org/members/422652-skyrangerpro) quoted the AAIB report: "There was significant displacement of the cockpit overhead switch panel
which appeared to have been driven downwards on to the upper surface of
the instrument panel coaming. skyrangerpro (http://www.pprune.org/members/422652-skyrangerpro) same post: Now to me that calls into question the reliability of the assessment of the position of all switches, particularly in the overhead cockpit True.
Especially as being "driven downwards onto the upper surface of the panel"
would mean that any switch that touched said panel during being driven
would be flipped into the "back" position, typically meaning OFF. :ugh:

[email protected]

24th Oct 2015, 11:49

CJ Romeo - one of the biggest problems pilots have is that engineers design the aircraft and its systems to solve the engineering problems not to make pilots' jobs easier or safer.

In an engineer's brain, having to switch pumps on and off is a straightforward task that anyone can do - right up to the point where that person is flying the aircraft, prioritising tasks and making weather decisions whilst operating in a cockpit with lots of other brilliantly designed systems, in the dark and over relatively inhospitable terrain.

SASless

24th Oct 2015, 12:01

Reely,

Beating your head on the wall.....really?

Why would the same exact pairs of switches be in the same position even though right next to one another in the over head panel.

What is more interesting is the configuration noted by the AAIB is exactly opposite of the switch position one would assume would be the case for normal operations.

This switch position thing is one of many issues that needs explaining if we are to make sense of what happened that night. Sadly, there is not going to be anyway to know definitively how they came to be in the positions they were found.

They could have been moved there by the Pilot, moved there by the Impact, or a combination of both....how does one determine the truth of the matter?

falcon900

24th Oct 2015, 12:12

The AAIB report makes reference to issues with the fuel probes on G-SPAO earlier in the year, and explains that these were resolved. It does not explain whether the faults became apparent while the aircraft was in flight, and who was flying it at the time. I am wondering whether the accident pilot had some history with spurious fuel warnings on this aircraft.
Having re read the report this morning, I am curious as to why so little is said about the Bothwell/Uddingston/Bargeddie taskings. Without these interventions, the aircraft would have made it back to base, even with the transfer pumps off. The Bothwell and Bargeddie taskings are described as routine, (no description is offered for the Uddingston tasking) , but we are not told what constitutes routine for a police helicopter. It seems absolutely inconceivable that nothing was said over airwave during this period. Surely the aircraft would at least have had to have reported on the outcome of one task before moving on to the next? The nature and perceived urgency of these requests would have had a direct and material bearing on the workload and behavioural dynamic in the cockpit, and could not be more relevant.
Also missing is any form of analysis of the operational records of the Police helicopter unit. I would have thought for instance that some form of review of fuel loads at landing compared to MLA might have provided a meaningful insight into culture?

Sky Sports

24th Oct 2015, 12:34

Let's put the switch position debate to bed once and for all.

The AAIB are very professional and thorough. If there was the slightest possibility that the switch positions had been changed by an impact with the instrument console, then they would have looked to see if the switch was bent, or witness marks/paint transfer were evident.

There is no conspiracy here on the part of the AAIB or the manufacturer.

If you are told you are low on fuel, you RTB.
If you think there is a defect in a system, you RTB.
If you have been flying a 135 for 1:37, at night, over a city, you should be RTB.

DrinkGirls

24th Oct 2015, 15:18

If you are told you are low on fuel, you RTB.
If you think there is a defect in a system, you RTB.
If you have been flying a 135 for 1:37, at night, over a city, you should be RTB.

Thanks for that Sky Sports, that's genius, we hadn't thought of that. :D

But he didn't, did he? He wasn't a risk taker, so why did he do it??
I don't have the answer, but knowing Dave well, I don't THINK he would have been so cavalier in his flying. SOMETHING made him feel that all was ok. Personally, my OPINION is that he saw the same 'picture' as G-NWEM had in the report. It made him doubt the warnings (incorrectly) and when he realised what had happened, he made incorrect switch selections under EXTREME pressure.
So you can't put the switch position thing to bed with the information that has been released in the report. It doesn't exonerate the burden on the pilot, but it could start to explain why he did it.

falcon900

24th Oct 2015, 15:32

Air Police,
I hear what you say, but the report specifically refers to Routine surveillance tasks, and refers to their completion before proceeding to the next task. If the crew were acting autonomously at this point, and there were no communications, how have the AAIB been able to conclude that there were discrete tasks, that they were routine surveillance, and that they had been completed? I take it you would agree that if the aircraft had been assigned to a task, it would be odd to assign it another without knowing the first was complete?
I also wonder whether Police Scotland were able to shed any light on events on the ground that night?
Events in the Bothwell area that night seem to me to be at the crux of this tragedy, and worthy of closer examination.
As for reviewing the landing fuel state records, I again hear what you say, but given how fastidious the AAIB have been in outlining all of the other steps they have taken, it would seem odd to exclude this one. Interesting that they note the operators increase of MLA in the aftermath of the accident though

DrinkGirls

24th Oct 2015, 17:02

The operators MLA increase was in response to NWEM, not SPAO

Heathcliff

24th Oct 2015, 17:10

"Thanks for that Sky Sports, that's genius, we hadn't thought of that.

But he didn't, did he? He wasn't a risk taker, so why did he do it??
I don't have the answer, but knowing Dave well, I don't THINK he would have been so cavalier in his flying. SOMETHING made him feel that all was ok. ... It doesn't exonerate the burden on the pilot, but it could start to explain why he did it."

Well said. (Sorry, I don't know how to quote but that is the perfect answer to Well I'm a really good pilot and I would never do x y and z".)

Reely340

24th Oct 2015, 17:24

SASless

Beating your head on the wall.....really?

<snip>
This switch position thing is one of many issues that needs explaining if we are to make sense of what happened that night. Sadly, there is not going to be anyway to know definitively how they came to be in the positions they were found.

They could have been moved there by the Pilot, moved there by the Impact, or a combination of both....how does one determine the truth of the matter?Sorry, my bad, let me detail that "beating my head onto the wall" :
That tiny half sentence of the report describing that the over head switch board got dislodged and moved downward over the cockpit panel, totally changed the weight of the"fact" where the switches were found to be!

In flight they could have been exactly as there were found post crash, or directly opposite or any mix in between, unless someone determines by abrasion analysis or other magic how they came to be in the positions found.

Hence the head banging simply referred to the extreme deterioration of that "fact" caused by said little sentence
in relation to how many people hinge all their blame (on pilot or manufacturer) on that rather soft evidence.

G0ULI

24th Oct 2015, 18:10

Reely340
The supply tanks to the engines were found to be empty. The pump switches that supplied fuel from the main tank which still contained fuel were found in the off position. The adjacent prime switches were found in the on position. If the impact forces in the crash were sufficient to change the switch positions, all the switches would have been found to be either on or off and not as found, two on, two off. The switches were found to be in the exact reverse positions to those expected in normal flight. Only one person on the aircraft was responsible and permitted to operate those switches, the pilot. QED.

SASless

24th Oct 2015, 18:41

Reely makes good points as does Gouli but the truth is we are assuming the Pilot moved the Transfer Switches to the OFF position prior to the Crash and that the Prime Switches were turned ON by the Pilot.

As odd as those Switch positions were....they do in fact make sense in a left handed way if one assumes the Pilot mistakenly activated the Prime Switches thinking he had turned the Transfer Switches to the ON position.

That the Overhead Switch Panel made contact with the Glareshield Coaming does not guarantee any switches were moved by that contact or the G Forces sustained during the crash.

We do have to correlate other indications of what position the Transfer Pump Switches were in and had been in for at least long enough to generate the Caution/Warnings seen in the memory of the various systems.

It does appear the Pilot mistook the Prime Switches for the Transfer Switches in my view....as the suggestion during a Low Altitude loss of all engine power and the resulting loss of Avionics and other systems....the Pilot would be using the Prime Switches in an effort to restart the engines....but forget to ensure the Transfer Switches were in the ON position...seems a bit far fetched to me.

If I got a Fuel Low light in the 105/117/135....with their similar fuel system design....the first thing I would have done is ensure the Transfer Switches were on.....and would have done that check when I saw fuel low Lights illuminating.

In the dark....Single Pilot....with things going wrong...it would be very easy to confuse Transfer Switches for Prime Switches.

Flying Bull

24th Oct 2015, 19:42

Hi all,

we can discuss forever - cause we won´t get the answers cause there was no recording....

What we can do is learn a lesson.

Which is - start to listen to your bird.

With every action taken on bord the helicopter, we get a feedback from it in one way or another.
Lets not assume, that the action will take place - check, that the results correlate with our actions, the lights go on/off, pressure builds up and so on.
Thats the way to find mistakes we make with touching the wrong switches, doubletap ones, switching defect equipment and so on - in time.

And - I have to grab my own nose - keep up with the handbook - it is astonishing, how much information ones brain blurres, if time goes by...
Stay villigant - and stay alive

"Flying Bull"

Sky Sports

24th Oct 2015, 19:53

Thanks for that Sky Sports, that's genius, we hadn't thought of that.
SOMETHING made him feel that all was ok.

DrinkGirls, I can appreciate that Dave was your mate and until that night he wasn't a risk taker, but the point I'm trying to make is that of basic fuel calculating.
Forget switch positions, warning lights, audio warnings etc. for one minute. He knew his fuel load on take-off, he knew the burn rate, he knew his endurance, he knew his flight time. He/they accepted that last tasking with an aircraft fuel state that was already lower than the aircraft had landed with in the last 125 sorties.
Even if the aircraft systems were all lying to them, and they had no warnings at all, Dave must have been thinking, I've been up for 1:37 this is going to be tight.
After that kind of flight time, what could possibly make him think that all was ok.

rakker

24th Oct 2015, 20:56

What can we (possibly) learn from this accident (just my thoughts and appologies for my very limited understanding of the Britisch language) ?

1. The fuel system needs to be changed: Why does the pilot has to put the XFER pumps ON or OFF depending on helicopter attitude ? The XFER pumps should be left on all the time, the system should switch OFF the respective pump if its running dry for 5 minutes and it should switch ON if it senses Fuel again AUTOMATICALLY. Do not bother the pilot with this task. Remove the XFER pump switches.

2. The CAD system should be black when flying in normal conditions. No room for advisory lights here. No room for the fuel indication also. There is too much going on on the CAD. I often dont bother to look at it at all.

3. The Master caution light has to be placed in a lower position. I cant see it even when my chair is in the lowest position.

4. Make the difference between the left and the right supply tank larger. So you have at least 5 minutes to understand that you are in a bad situation (and not a few seconds depending on aircraft attitude and movement).

5. Do not fly missions all the time using all the fuel there is. Everybody wants you to do this and we as pilots like to please our "customers". Land with at least 30 minutes of fuel, get more (night) refuel spots easily available.

6. Put your swivable landing light and the internal communications on the Essential busses. When two engines fail you are busy enough.

7. Fly realistic simulator sessions for at least six hous per year.

Just my thougts but the accident has got me thinking (for what its worth) about my own flying in the 135, certainly at night.

Reely340

25th Oct 2015, 06:45

..and pratice EOL in twins twice a year.
In situations mirroring your kind of work.
(read: in the night if you work at night).

Lacking that skill was the major reason why all had to die.

SilsoeSid

25th Oct 2015, 07:44

There is so much wheat and chaff in this thread that I hope any lawyer building a case based on the information gleaned in this 'professional pilots forum' gets it sifted. (Reely340's last post about practise EOL's being a classic example)

Eg;
Did three people really totally ignore all those warnings?
How do the NVG impinge on the roof when in the stowed position?
Would one really consider an engine restart at 1000' agl over a city?
How much use is the equipment that the EM Shed Buss will give you back?

Etc etc

Reely340

25th Oct 2015, 08:06

There is so much wheat and chaff in this thread that I hope any lawyer building a case based on the information gleaned in this 'professional pilots forum' gets it sifted. (Reely340's last post about practise EOL's being a classic example)Please elaborate :confused:

If pilots do not regulary pratice "twin EOL" (at least with power recovery at 10ft AGL), how should they be able to survive twin flame outs?

I'd say besides all switch position mishandling and warning bells ignorance the main issue here is
the demonstrated inability of a +5000h CPL to properly autorotate to somewhere close to ground.
(according to the report he did try, passing the 97% rrpm threshold multiple times)

Or would you pull out the exposure time vs. probability regime
and file such incindents under **** happens? :(

Sir Niall Dementia

25th Oct 2015, 09:19

Afraid I'm with SkySports on this;

How on earth do you accept another job after flying for so much time? Was there a culture of landing below MLA? The police guys on board heard the warnings, the one in front probably saw them. We don't know what conversations took place, and I suspect this is where the AAIB are coming from.

I've flown 135's for ten years (not in a police role) and have always found the CAD really simple, as is fuel planning. During those ten years I've twice had fuel indication snags, both times I've landed knowing that although the supply tank was showing empty, there was fuel as the relevant engine was running, I was well inside my planned endurance and there were no RED FUEL LOW warnings. When the sensor fails in my experience the affected tank goes black if its' a supply tank and gives ratty data if its' the main.

I have (in a different type) found myself really tight on fuel, at night in a hostile environment and I was mighty scared. But, since my earliest instructor banged on at me about fuel guages and the importance of knowing how long your fuel could last my final action before take-off is to hit a stopwatch. Should the indications fail you instantly have a time indication as a final check.

SND

DrinkGirls

25th Oct 2015, 09:52

In your experience it goes black?
So not much experience of the fault then?

If the sensor fails, it does indeed go black.

However if the sensor is water contaminated, it shows the supply tank to be permanently full.

Listen, no one on this thread seems to doubt that Dave did wrong, even with the possible alternate scenarios on dodgy fuel gauges. My crusade is that IF the gauges fatally confused him, this could happen again. Surely it is better to say, "we don't know if gauges were involved, but there is an element of doubt, let's fix that possibility".

chopjock

25th Oct 2015, 10:15

SND
my final action before take-off is to hit a stopwatch. Should the indications fail you instantly have a time indication as a final check.

Of course that would only be of use if full tanks on take off.

Heathcliff

25th Oct 2015, 11:47

"Listen, no one on this thread seems to doubt that Dave did wrong, even with the possible alternate scenarios on dodgy fuel gauges. My crusade is that IF the gauges fatally confused him, this could happen again. Surely it is better to say, "we don't know if gauges were involved, but there is an element of doubt, let's fix that possibility".

Indeed, though I suppose if you keep convincing yourself you know everything that happened in the cockpit that night, and that you'd never ever do x y or z because you're such a good pilot, it distracts you from the fear that one one it might happen to you.

Rakker, your English is better than some I have read on this board ;) and you make good points. If anything good comes out of this horror let it be lessons learned and changes made. Nothing else can.

Good Business Sense

25th Oct 2015, 12:10

Of course that would only be of use if full tanks on take off

Every commercial company, airline I'm aware of has a system for checking fuel before departure involving arrival fuel, pick up etc - any material discrepancy is investigated ... applies from 747s down. It's not often airliners/most aircraft fill their tanks - some not for years on end. The statistical history of this pre-departure check forms a quality control check on the gauges and burn figures.

Don't know a pilot who wouldn't monitor the time in flight (chrono etc) against fuel whether you're flying a 747 or something smaller.

Turbines are very easy to monitor as fuel flow is very accurate- having said that, I imagine, that it must be a lot more difficult with helicopters when hovering etc etc as opposed to straight line cruise A to B.

Cows getting bigger

25th Oct 2015, 13:59

In many respects, this accident has the same hallmarks as the Mull of Kintyre Chinook. We'll never know what happened, precisely, but there are a large number of things that can be taken on board to reduce the chances of it happening again.

SASless

25th Oct 2015, 14:07

I think I am like most, Dave was one of us, had a similar background and training as most of us, and in all likelihood could very well have been anyone of us except they way things go when it comes to being in the seat that night.

What we are trying to work out is why this happened to Dave as it could have been one of us instead except for Luck, Fate, or sheer happenstance.

I am trying to make sense out of what we know...and trying to put myself in Dave's Shoes that tragic evening.

Everything tells us it should not have happened to him....yet it did.

That is what is frightening about all of this...it could very well have been anyone of us if it could happen to Dave.

I don't know him...doubt I ever met him....but I know in my heart he was a good guy with good training and apparently made some mistakes.

I don't fault him personally and only hope to see it all figured out so we can learn from this sad loss of lives and hopefully prevent future losses to the same causes whatever they turnout to be.

Distant Voice

25th Oct 2015, 14:55

Mechta

25th Oct 2015, 15:53

This may appear to be a daft question to some of you specialist, but why do we have main tank and a co-located split supply tank? Why not have a split main tank with gaps in the baffle feeding the engines?

Presumably because as the aircraft attitude changes, some parts of the main tank will be left dry. The engine feed tanks are kept full, thus giving a constant head of fuel supplying the engine and a considerable time delay between change of aircraft attitude and loss of fuel pickup. A feed tank could be thought of as a glorified float chamber on a carburettor.

Whilst it would be possible to have one tank feeding both engines directly, compromises would have to be made to the shape of the tank and the shape of the helicopter to get a reliable supply.

skadi

25th Oct 2015, 18:05

Question: Was this particular helicopter equipped with fuelflow and endurance indication on the CAD?

skadi

NR DROOP

25th Oct 2015, 18:10

Question: Was this particular helicopter equipped with fuelflow and endurance indication on the CAD?

skadi

Not fitted.

Sir Niall Dementia

25th Oct 2015, 18:12

DrinkGirls;

Just my experience of what happened with supply tank indication failure.

Chopjock;

Fuel pick up is (should be always balanced) against what you had and what the bowser gave you.

SND

RVDT

25th Oct 2015, 18:39

This may appear to be a daft question to some of you specialist, but why do we have main tank and a co-located split supply tank? Why not have a split main tank with gaps in the baffle feeding the engines?

Even though it is a Part 27 aircraft it does have a Cat A Supplement so it must meet most of the design requirements of Part 29 Cat A as there are no criteria within Part 27.

Therefore -

29.903 Engines.

(b) Category A; engine isolation. For each category A rotorcraft, the powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or the failure of any system that can affect any engine, will not—

(1) Prevent the continued safe operation of the remaining engines; or

(2) Require immediate action, other than normal pilot action with primary flight controls, by any crewmember to maintain safe operation.

29.953 Fuel system independence.
(a) For category A rotorcraft—

(1) The fuel system must meet the requirements of §29.903(b); and

(2) Unless other provisions are made to meet paragraph (a)(1) of this section, the fuel system must allow fuel to be supplied to each engine through a system independent of those parts of each system supplying fuel to other engines.

With the usual caveats -

chopjock

25th Oct 2015, 19:02

it must meet most of the design requirements of Part 29 Cat A as there are no criteria within Part 27.

And these requirements are meant to make a Cat A aircraft safer? Makes you wonder eh?
Perhaps keeping it simpler would be safer.

Sky Sports

25th Oct 2015, 20:12

No doubt that those requirements were written as a result of, or experience of, a previous accident.

paco

25th Oct 2015, 20:59

Or the designers were just too lazy, like requirng a busy pilot to count the number of times the collective is rasied as on the 350.

Phil

Thomas coupling

25th Oct 2015, 22:52

Is anyone in any doubt any more, why this all went horribly wrong?

Four things are FACT:

1. Fuel switches were in the incorrect position.
2. The 10 minute to land warning was ignored.
3. The pilot was unable to carry out an EOL successfully.
4. The pilot was very very experienced.

On that dark, wet night over Strathclyde all the holes in the swiss cheese - lined up.

NO -ONE is infallible. WE ARE NOT COMPUTERS.

G0ULI

25th Oct 2015, 23:41

Looking at this incident from another direction, every experienced car driver can recall a journey where they started off and arrived at their destination with no recollection of the journey itself due to being distracted by other thoughts.

Is it unreasonable to suggest that a very experienced helicopter pilot might not also be capable of going through the motions of flying a helicopter while not being totally focused on the job?

At the time the supply tank switches were switched off in response to a warning they were running dry, it would appear the pilot was reacting normally. At some point between then and when the low fuel messages appeared, something appears to have distracted the pilot to such an extent, he was effectively just going through the motions. The warnings were acknowledged but not actioned. Only when the first engine flamed out did the pilot snap out of his distracted state and was probably very confused as he struggled to catch up with what the helicopter was doing.

The second engine spooling down would just add to the confusion and possibly utter bewilderment as nothing appeared to be happening as described in the manuals.

So the question is, what event could happen in mid flight that would give rise to such a level of distraction in an experienced pilot? We can say with reasonable certainty that there was no significant equipment failures in the helicopter and it was basically airworthy and with enough fuel to return to base safely, although below the mandated safety limits. So what else could have occured during the trip back from Edinburgh towards Glasgow?

Would anyone on this forum admit to having been flying along in a soporiphic state only to be startled into awareness by the Nr horn sounding, or a sudden engine failure? I can't imagine it hasn't happened before.

SASless

26th Oct 2015, 01:24

I once attended a Training Course where the Conditions White, Green, Yellow, and Red of Pilot Attentiveness was discussed.

It made a lot of sense back then and bears repeating.

White.....you are somewhere warm, cozy, smelling of fine perfume and freshly washed Hair....or whatever equivalence does that for you. Things are safe, your mind is anywhere but in the Cockpit.

Green....you are in the Cockpit, everything is going fine, the weather is great, bags of fuel, things are just going as planned.

Yellow....You are in the Cockpit and sitting a bit more upright than normal...something is not quite right but nothing dire noticed yet.

Red....You are sat straight up....you Heart is over speeding....you stomach is in your throat...butt cheeks clinched tight enough you could trade the Shoulder Harness and Lap Belt for a Trailer Hitch Ball and be firmly fixed to the seat....and lots of stuff is going badly wrong.

Transition from each Condition/Mode should be gradual, unhurried, and planned ahead....the rate of change causes distress the quicker it happens....with a significantly reduced accuracy in reaction time and appropriateness of that reaction.

We should never go more than one Condition per change....and never knowingly operate in either White or Red Modes.

Green is fine....but Yellow is the best.

That means you are awake, thinking, checking what needs to be checked, monitoring what needs monitoring, and making sure your plans are still intact and if not you are aware of it and taking corrective action.

If some thing goes wrong....it will not be a surprise or shock to you...even if you only generate a mere second or two of advance warning.

Get yourself a Yellow Sticker and put it somewhere you will see it in your Cockpit....it works!

FH1100 Pilot

26th Oct 2015, 01:48

Progress. I think about it a lot. Like the transmission in the Sikorsky S-92 with the dual oil pumps that can not independently supply sufficient pressure to preclude an emergency situation if one fails. Now there's some great design progress, eh? :ok:

My experience is not with the EC-135. I flew the old, antique Bo-105. It has a similar fuel tank/supply setup as the EC-135 apparently. You had to turn transfer pumps on to move fuel forward from the main tank to the little supply tanks in which were the "real" fuel pumps that sent it up to the engines. The transfer pumps did not have caution/advisory lights to tell you when they were off. PHI (knowing that we dumb pilots would sooner or later forget them) added white "Transfer Pump OFF" lights to the dash. Turning the pumps on extinguished the lights. The system was not foolproof. The lights were white. On a bright, sunny day they could "disappear" under the glare shield. Ask me how I know. Wait- don't ask.

As SASless says, no self-respecting Bo105 pilot would *ever* deliberately turn the transfer pumps off in flight. If you did, you'd run out of fuel in about twenty minutes (on a good day) when the supply tanks ran dry. Or maybe it was eleven minutes - I don't remember. What I *do* remember is that we never shut the transfers off.

The fuel quantity indicator system in the Bo-105 was stone-simple.

You had a fuel gauge with two needles. One was for the main tank and the other, the supply. Because of where the fuel quantity sensor was located, in forward flight (about 10 degrees nose down) the main tank fuel indicator would show empty even when there was plenty of fuel in it. You did not use the gauge for the main tank in cruise; you used your watch. (For aviation-savvy but non-pilot passengers who were new to the Bolkow, it was kind of scary on a long flight to see the fuel gauge go to zero.) But if you ever saw your supply tank needle coming down, your LZ better be in sight.

I cannot believe that Eurocopter made the EC-135 "better" by requiring the pilot to periodically switch the transfer pumps off and on. That's ridiculous. That's not progress, is it.

Now then... We all know good pilots who've inexplicably come to grief in helicopters. It's hard for us to wrap our heads around it: How someone we know and admire could make such a dumb, fatal mistake? We arrogantly think that *we* ourselves would never do such a thing - so how/why did someone as good as "X" do it? Would a CVR have told us? Not necessarily. Would more training in full-down night EOL's have helped? I doubt it, but YMMV. Once that first engine quit I'll bet it was fair pandemonium in that cockpit, or at least a lot of, "What the hell is going on??" and a lot of cuss words. Things were surely happening fast.

I've said before and I'll say again: Helicopters are very easy to crash. The helicopter does not care how much experience you've got or how good a pilot you are or what your friends think of you. And neither you nor I are immune to making the same kind of fatal mistakes as the ones who've sadly, tragically gone before us. I know how close I've come over the years and I get shivers up and down my spine when I recall them. Grace of God and all that.

Look at those two guys who crashed the AW-139 taking-off in the fog from that rich guy's estate a couple of years ago. Should have been a "simple" vertical take-off through the fog layer. Set the hover attitude and then straight up: easy-peasy. But no, as he pulled pitch the PF started (inadvertently?) pushing forward on the cyclic. Did neither of the *two* pilots onboard see that the nose was going down, down, down? Did neither of them notice that the rate-of-climb indicator wasn't showing a climb? Apparently not. We think they had plenty of time to recognize what was going on, but I'll bet things happened pretty fast for them as well. Two qualified and experienced professional pilots killed everybody onboard that night.

We all make mistakes. Why the pilot of the EC-135 continued to fly beyond 1:30 makes no sense especially when he'd already received low-fuel warnings. "Everybody" knows the -135 doesn't have all that much endurance. He *had* to know he was about empty. And why he was messing around with the transfer pump switches with so little fuel left is extremely puzzling. That the engines ran dry with fuel onboard is simply inconceivable. What was he thinking?? Even a CVR cannot tell us.

There are a lot of unanswered and unanswerable questions. Some accidents are like that. Sometimes you never know. Sometimes all you can do is shake your head, accept that the pilot screwed up and move on with the knowledge that in our world sometimes things just don't make sense.

DOUBLE BOGEY

26th Oct 2015, 07:54

FH100 Great Post. Should be the postscript to this thread...but I doubt it will be.

Solar

26th Oct 2015, 08:02

Second Double Bogey on FH100's post.
Especially the reference to the CVR, couldn't see how that would have made any difference here.

DrinkGirls

26th Oct 2015, 08:07

Can't see how it would help?

Have you been drinking?

DOUBLE BOGEY

26th Oct 2015, 08:15

Drink girls, I believe what he means is the presence of a CVR in this case would not have made any difference to the outcome. Of course as AAIB point it it may have provided better insight to the circumstances leading up to the accident. Don't let your emotion cloud your reading skills!

Lascaille

26th Oct 2015, 10:06

That the engines ran dry with fuel onboard is simply inconceivable.

This is the problem. Absent mechanical failure this situation cannot happen in any number of other vehicles including the absolute simplest and safest.

If we need to turn fuel pumps off there is a feature for that, it's called a circuit breaker.

Operable switches for flight critical components need two positions only: AUTO / ON.

If there's a light to tell you when the pumps run dry there's an Auto feature available right there, and ON is the only sensible override. OFF override would be via the CBs which gives you a good clue you're doing something that's special circumstances only.

Unless you value the lifespan of the fuel pumps over the lifespan of the people inside, what else makes sense?

G0ULI

26th Oct 2015, 11:54

SASless and FH1100 Pilot

Thank you for your posts. Very helpful in trying to make sense of this tragedy.

rantanplane

26th Oct 2015, 12:31

On that dark, wet night over Strathclyde all the holes in the swiss cheese - lined up

as far as I remember conditions were CAVOK.
nice views over x-mas ready illuminated Glasgow.
perhaps a bit to dreamy, the conditions?
and it was Friday. Was it their last job? with the head half way on the way to the pup?

Just speculations, no CVR would tell us Dave's thoughts as it has been made clear. Thanks for the posts SASless and FH 1100. Nail on the head, I had goose skin afterwards. It's such sad story for a place which does not need accidents like this, especially if the good ones disappear.

Heathcliff

26th Oct 2015, 13:18

SASless and FH1100 Pilot

Thank you for your posts. Very helpful in trying to make sense of this tragedy.

Seconded; intelligent, well worded and sensitive. Thank you.

SASless

26th Oct 2015, 13:52

As to a CVR helping....oh yes indeed it would.

If all crew stations were monitored and we had the last thirty minutes of conversations amongst the Crew....we would know a great deal about their thinking re Tasking and any discussion the Crew about them.

I am quite sure there was some discussion by the Crew during the Flight and it would certainly give us far more insight into decisions made by the Crew that night.

We pretty much know "What" happened....but we are far from knowing "Why".

We would also know of any discussion about Warning/Cautions or fuel state.

We would have an audio record of any discussion about Emergency Actions such as landing out or diverting to a safe landing area.

Very adamantly I support the noting that a CVR would have provided much information that would go towards answering the "Why" part of this Investigation.

Reely340

26th Oct 2015, 15:51

But even with all logging and recording equipment imaginable,
what we still won't know is why the pilot lacked a helicopter pilot's basic
skill: autorotation.

That's not a beauty contest, but there's lot in between a 100G impact and a successful AR.
This was not pitch dark countryside, it was Glasgow at 10pm, lots of illuminated tarmac.

It certainly doesn't have to be perfect, even dropping the ac from 20ft with 0 rrpm would have them walk away.
Hell, an EC135 can even fall down 7 stories from a hospital's helipad and all survive:
http://versa.bmvit.gv.at/uploads/media/FU-1.5.06-Endbericht_03.pdf
(Sound like Cabriesque safety to me.)

If I were the CAA,
I'd mandate annunal demonstration of all engine-at-idle autorotations to 10ft skid height.
If you can't do that in all ships you were issued a TR go back to flight school.

And of course I'd threaten to rest all EC135 airworthyness until they get the zero attention fuel pump switches I was outlining before or the BO105 fuel pumps SASless was describing. :ok:
And not having essential electronics (rrpm, ias, radalt) driven by battery and generator, an ac's night VFR certification would be voided.:E

huntnhound

26th Oct 2015, 15:51

This was a tragic event. In my limited amount of time on board four aircraft types over twelve years I dont ever recall being in such a "low fuel" situation.
Whilst the enquiry seems to point directly at pilot error, I cannot let it pass that the all of the pilots I flew with were consumate dilligent professionals, and its thanks to them that I have been drawing my pension, unlike the two officers on board that evening.
Thank you guys.

Torquetalk

26th Oct 2015, 16:40

"If I were the CAA,
I'd mandate annunal demonstration of all engine-at-idle autorotations to 10ft skid height.
If you can't do that in all ships you were issued a TR go back to flight school."

What do think happens during an LPC? And an OPC for that matter.

chopjock

26th Oct 2015, 16:51

What do think happens during an LPC? And an OPC for that matter.

Do LPCs on twins get both throttles chopped and an auto rotation to the flare ?

Or briefed that double engine failure will never happen so just practice OEI procedure?

Thomas coupling

26th Oct 2015, 17:03

I got flamed for mentioning this previously in this thread but for those in the know, they understand where I am coming from. It may be a language issue:
This particular pilot hadn't done an EOL auto for possibly decades.
In his time prior to becoming a police pilot (UK) he flew Chinooks. I believe (stand corrected) he flew them for 13 years?
Chinook pilots don't practice switching all engines off and having to physically fly tons of inert metal down onto the ground. In fact 'almost' all mil pilots no longer exercise this luxury - it's too expensive to train like this in the event of a mistake.
Then he joined the police (maybe AS355) and flew the Ec135 twin.
NO police pilots fly EOL's to land.
Almost ALL mil and police pilots practice autos (and my definition of an auto is bringing both engines back to FI, flying the profile and then recovering to a set minimum height with both engines constantly 'on tap' throughout ANY mishandling of Nr during the descent. It is an OK process, captures most issues, most of the time. BUT it is not the same as a proper E.O. descent where all engines are removed from flight and unavailable throughout - Nr takes on a totally different trajectory. Lose it below Nrmin at your peril.

I think - overall, David was not only shocked/surprised when both donks stopped (the silence must have been very spooky, possibly frightening) but when Nr then went walk about on a spectrum he was unfamiliar with - he didnt have time left to 'get accustomed' to an old regime he probably saw and recognised 20+ years ago.
Add to that no rad alt or L lamp, wet rooftops and road surfaces and before you know it - Nr< 60-70. Goodbye Vienna.

Hughes500

26th Oct 2015, 18:28

Just curious here, I am essentially a VFR single engine pilot. Any sudden yaw to the left ( normally fly US machines ) has my left hand about to punch the lever down. This has become muscle memory and in grained over 7000 hours of flying. When doing my first twin rating found it very hard not to put the lever down when having one donk put back to idle even though my brain knew there was another keeping us flying ( well just in an F2 355 !!)
Now the pilot in Glasgow flew twin engines for almost all his career so was it the reverse of my case that happened, i.e. one donk goes pull the lever up second goes natural reaction pull the lever up. Hence the Nr almost nil ???

Might go and find my bone dome and hide in a trench from the incoming :uhoh:

Reely340

26th Oct 2015, 18:40

Thomas coupling (http://www.pprune.org/members/19161-thomas-coupling), my hat is off to that honest statement of yours! :D:ok:
It is perfectly in sync with what a freind of mine told me (then HEMS in BO105, now HEMS in EC135 in winter and long lining in AS350 in summer, FI for both BO and EC):
"One doesn't practice engine-idle autos to 10fr skid height like you newbies in S-300C. Reason: too expensive when something with reapplying power gos foul and this szenario is deemed so extremely unlikely."

So my take is that an unknown but quite sizable amount of non-pprune :E CPL in service quite probably have no recent experience of idle engine autorotations.

A) If we fix dangerous user interfaces (overhead switch vs. NVG stowed, tactile differences of controls) of the machines and remove unnecessary but potetially dangerous setups (like non dry-run safe fuel pumps) we actually could leave the recency of experience requirements as they currently are. Manufacturer "pays" the cost.

B) Or we go the long way and make sure that every helo pilot does know how to safely autorotate to safe height. Then we all pay the cost via insurance premiums/higher lease rates.

W/o wanting to sound atrocious, both regimes can be argued in favour of, but implementing none of those two options is unacceptable.

jellycopter

26th Oct 2015, 18:55

I find it difficult to comprehend the argument that the pilot didn't have the skills, or presence of mind to enter and sustain autorotation.

The report makes mention that the variation of Nr above and below 97% corresponding to a reduction in speed shows an attemp to enter autorotation. Flare might well have made the initial recovery of Nr possible but then after flare effect diminished, it became unsustainable.

I can't find any mention in the report of a check of collective control rigging.
Also, what about snagging the collective? I've not flown the 135 or indeed know what is carried in the cockpit but could a foreign object have found its way under the lever and stopped it being lowered fully? It wouldn't be the first such accident in helicopters.

Torquetalk

26th Oct 2015, 19:04

Chopjock, you will, I am quite sure, be aware that simulators are used for "real" autorotations in twins. They do a very good job of this and for crews who havent got much of an experience base in autos, allow errors to be made without the consequences being ruiningly expensive.

I think the reaction time from flying twins is an important point. SE pilots get drilled to react quickly. My guess is that pilots flying twins regularly react less quickly. This is not always a disadvantage as things can go wrong with the engine or fuel system which wont be helped one bit by lowering the lever quickly without a quick diagnosis of whats wrong.

Practicing autos in big expensive aircraft is loaded with risks of overspeed and mismanaged landings. Personal opinion is that any operator putting their entire flight crew through real aircraft EOL training would be quite barmy. And it is probably no coincidence that they are not required to and dont.

I seem to recall that 25% of all helicopter accidents in the US are practice autos gone wrong.

Did Dave get regular (annual?) sim sessions?

[email protected]

26th Oct 2015, 19:06

If I were the CAA,
I'd mandate annunal demonstration of all engine-at-idle autorotations to 10ft skid height.
If you can't do that in all ships you were issued a TR go back to flight school.Presumably at night as well as by day to provide adequate assurance that no-one will crash into a pub........no, didn't think so.

Heard a rumour that the transfer pumps create interference with the camera or its downlink and it is considered normal to turn them off - this would explain why an experienced pilot cancelled the low fuel warnings several times.

jellycopter

26th Oct 2015, 19:10

Crab

"Heard a rumour that the transfer pumps create interference with the camera or its downlink and it is considered normal to turn them off - this would explain why an experienced pilot cancelled the low fuel warnings several times."

Surely if this was the case, the investigation would have unearthed it?

NR DROOP

26th Oct 2015, 19:10

Presumably at night as well as by day to provide adequate assurance that no-one will crash into a pub........no, didn't think so.

Heard a rumour that the transfer pumps create interference with the camera or its downlink and it is considered normal to turn them off - this would explain why an experienced pilot cancelled the low fuel warnings several times.
Transfer pumps cause no interference.

[email protected]

26th Oct 2015, 19:20

Other 135 pilots appear to differ with your opinion but perhaps it is a historic issue that has been engineered out. As I said - a rumour.

The investigation would only have known it if someone told them or they thought to ask the question...did they??? I don't know.

Can someone come up with an explanation for why the low fuel warnings were cancelled so often without further action?

handysnaks

26th Oct 2015, 19:21

Crab, I second NR Droop. You can cast that rumour into the same bin that holds the Roswell Alien and Moon landings were fake rumours.

ShyTorque

26th Oct 2015, 19:43

Hughes500,

Now the pilot in Glasgow flew twin engines for almost all his career so was it the reverse of my case that happened, i.e. one donk goes pull the lever up second goes natural reaction pull the lever up. Hence the Nr almost nil ???

I haven't been able to work out why you think any helicopter pilot would do this; it certainly defies logic.

[email protected]

26th Oct 2015, 20:12

Handysnacks - you and NrDroop may well be right but why would you repeatedly cancel a fuel low warning unless you were expecting it to happen and were in the habit of automatically cancelling it?

Thomas coupling

26th Oct 2015, 21:04

Hi Crab: because of the nose up attitude in the hover, the pumps run dry at low fuel levels. So, you have the option to depart the hover and level the a/c immersing the pumps in fuel and extinguishing the captions, OR, cancelling the captions every few minutes, OR switching the pumps off until you depart the hover at a time to suit you and then switch them back on.............................................if you remember:eek:

handysnaks

26th Oct 2015, 21:19

Crab, if I had to guess, then I would say that he was actually cancelling the red low fuel warning to get rid of the audio gong that would accompany the Low Fuel 1 and/or 2 warning. The red low fuel warning would still be illuminated on the warning panel.

[email protected]

26th Oct 2015, 21:23

TC - but as I understand it, the pumps have a run-dry capability of 20 mins - more than enough for a short job in the hover, especially when you know you are low on fuel.

It seems that a poor design feature has been 'worked-around' and it has been seen as 'better practice' to turn the pumps off and deliberately cancel the warnings - that is not a healthy ethos.

Handy = yes, I agree, it seems the visual warning captions remain -I don't know if it is a single gong or a repetitive one.

Jet Ranger

26th Oct 2015, 21:46

Repetitive one

Thomas coupling

26th Oct 2015, 22:51

Crab:

I can only talk for myself and my actions when I did this job.

At night in particular, I wanted always to have a clear caution panel in front of me - in preparation for that unexpected mal;function to flash up.. If the low fuel warnings kept illuminating whilst I was in the hover, I would either (with the permission of the crew who were tracking someone for instance - on camera and didn't want to lose that target), "nod" the cab fwd thus immersing the pick ups in fuel and extinguish the light(s),which gave me breathing space before the run dry caption(s) came back on again - OR, if it was a prolonged hover and I was unable to manouevre temporarily - switch the pumps off. I drilled myself to ensure they came back on again after departing the hover (but as we see - this is not foolproof).

I hasten to add - in mitigation - this was a reasonably rare occurence because this scenario only manifested itself at the edge of my endurance and I would always be of the mindset that this would have to be the last hover, or close to calling it a day (or night).
MLA @ night was higher than day (90kg vs 60Kg from memory) leaving me an adequate barrier between these constantly illuminating captions telling me "low fuel" and actually having low fuel.
Where I struggle with this crash is that the pilot "probably" did what I did - possibly several times over during prolonged hover - each time eating into his night MLA reserve and apparently creeping inexorably closer to his 'actual' minimum useable fuel remaining. It may have been that he was within touching distance of landing at base and this might have given him false security.
The EC135 'density compensator' type fuel capacitors that indicate fuel content weren't in my opinion - rocket science technology. They always gave sporadic changes in the amount remaining, they always 're-adjusted' themselves after landing (level attitude). One couldn't always rely on them to give out exact digital data that was stable. One simply built this into one's processing and planning.
So one would be sitting in the hover for a considerable few minutes (say 10+) and the cops would ask for time remaining airborne and you would go thru the basic maths minus the MLA. Then - after leaving the hover and stabilising in the cruise, one would find that endurance had then 'magically' improved? So there was always this doubt in one's mind as to exactly how much endurance one had - to the minute.

Once the engine(s) shut down - I think this required a totally new mindset. It required the human brain to ramp up from simply being 'aware/alert'.........instantly......to the limits of arousal, bordering on stress and even resignation as the situation gets further out of control.
This is where training by rote kicks in................but one needed to have done the relevant repetitive (EOL) training for that to happen...and I believe this was not the case.

SilsoeSid

26th Oct 2015, 23:17

It would seem from the report that most if not all of the systems were found to be working correctly. 'System tested no fault found.'
Funny that in times gone by we used to fix the old TV set by giving it a quick thump :suspect:

G0ULI

27th Oct 2015, 01:14

SilsoeSid that is wickedly funny. :D

megan

27th Oct 2015, 02:08

Do LPCs on twins get both throttles chopped and an auto rotation to the flareAll our medium twin instructors gave autos, straight in, 180 and 360, with the throttles being brought up during the flare. One, if he judged you were doing a good job, would leave the power at idle and let you do it to the ground, this part being unbriefed, and you only realised what was happening when the collective pull on levelling decayed the revs. Was a one off event per student, great confidence builder, but don't know how he slept at night putting so much on the line for the benefit of the student. He never had a student stuff it up, so says a great deal for his judgement of the students ability during the auto in question. Many thanks Bruce Townsend, one of natures true gentlemen.

[email protected]

27th Oct 2015, 07:19

TC - it would seem then that the fuel system on the 135 is not fit for purpose in the Police role since that involves a lot of slow speed/hover surveillance.

One of the solutions - the nod - seems to be counter-productive since it sends fuel away from the tanks that directly feed the engines.

Pragmatic solutions to get the job done but all to overcome poor engineering design.

RVDT

27th Oct 2015, 08:35

TC sez,

in preparation for that unexpected mal;function to flash up

Duh? Any successive caution will bring up the MASTER CAUTION no?

OR, if it was a prolonged hover and I was unable to manouevre temporarily - switch the pumps off.

WTF? This will NOT extinguish the CAUTION caption "F PUMP" so why bother? Why paint yourself into a corner as well as NOT OPERATING IAW WITH THE RFM.

The EC135 'density compensator' type fuel capacitors that indicate fuel content weren't in my opinion - rocket science technology. They always gave sporadic changes in the amount remaining, they always 're-adjusted' themselves after landing (level attitude).

Granted they have been around for a while but what else is there that is approved and certified? They will "re-adjust" themselves as they are "pitch compensated" and dampened via the CAD software.

Crab sez,

One of the solutions - the nod - seems to be counter-productive since it sends fuel away from the tanks that directly feed the engines

Er no it doesn't. TC is talking about the main tank not the supply tanks.

Do you guys make this sh1t up as you go along?

And when TC is referring to "low fuel" he is referring to a "F PUMP" CAUTION light not a "LOW FUEL" WARNING light I am sure or at least hope so. If there is fuel in the MAIN tank enough to cover the pump which you can determine by your current speed and the quantity on the CAD then the fuel pump shall be ON. Anything else is contrary to the RFM. The procedure in the RFM is to determine if you have a F PUMP failure or not which would be best to know as it may have consequences.

I was discussing this recently with an old school friend who went to planks with QF about 20 years ago after about 12K on helicopters. He mentioned when he was on the 747-400 LAX-SYD it was common to have transfer pump warning lights constantly on approaching SYD after ~ 13 hours. The phenomena is not unique.

efish

27th Oct 2015, 10:45

I keep asking myself, under what circumstances you could keep cancelling the low fuel captions and having no one else in the crew questioning your actions. And I keep coming up with the same scenario.
You tell the crew that we have plenty of fuel in the main tank and that your switching off the transfer pumps because you wish to see or demonstrate when low fuel 1&2 come on. So as the fuel in the supply tanks runs down the low fuel 2 comes on and you cancel it and then cancel it a further 2 times waiting for low fuel 1 to come on, it comes on you reach up and turn what you thought were the transfer pumps on and continue with that one last routine task. The low fuel lights illuminate again, but its OK you tell everyone I've turned the transfer pumps on and the lights will go out shortly. Then it all goes terribly wrong!

handysnaks

27th Oct 2015, 10:58

Efish. You cannot cancel the Low Fuel Warning or caution. You can only cancel the audio of the warning or the attention getter for the caution. The captions will still be there on the warning panel or CAD.

Reely340

27th Oct 2015, 12:13

Thomas coupling: OR, if it was a prolonged hover and I was unable to manouevre temporarily - switch the pumps off. I drilled myself to ensure they came back on again after departing the hover (but as we see - this is not foolproof).Interesting. If going for the switched at all, why not toggle between "front on" for cruise and "rear on" for hover?

SilsoeSid

27th Oct 2015, 12:26

"I keep asking myself, under what circumstances you could keep cancelling the low fuel captions and having no one else in the crew questioning your actions. And I keep coming up with the same scenario.
You tell the crew that we have plenty of fuel in the main tank and that your switching off the transfer pumps because you wish to see or demonstrate when low fuel 1&2 come on. So as the fuel in the supply tanks runs down the low fuel 2 comes on and you cancel it and then cancel it a further 2 times waiting for low fuel 1 to come on, it comes on you reach up and turn what you thought were the transfer pumps on and continue with that one last routine task. The low fuel lights illuminate again, but its OK you tell everyone I've turned the transfer pumps on and the lights will go out shortly. Then it all goes terribly wrong!"

Apart from the 'demonstrating the Low Fuel warnings' part which imho is utter nonsense, a big flaw in your scenario is that in addition to already having both transfer pump captions, when the prime pumps are switched on (inadvertently) the master caution flashes and the CAD lights up which has to be acknowledged. Additionally, the two Prime Pump cautions will be displayed on the CAD until the pumps are switched off.

However, the biggest flaw in your scenario is that it was the Low Fuel 1 that came on first, twice, before the Low fuel 2 came on and stayed on; I refer to table 3 of page 33.

efish

27th Oct 2015, 12:29

I doubt there's much ammo there for lawyers, as its a scenario which would be impossible to prove. As far as the indications on the CAD goes. I would assume that he had been operating on NVG and then removed them to operate over the city. One thing that has always annoyed me about the NVG switch is when switching from normal lighting to NVG lighting the CAD and VEMD displays always revert to fully dim and you have to turn the brightness up.
I know pilots do choose to remove the goggles to Relieve the neck strain. Personally I leave mine on as I think it puts you in a much better position to pick that landing site should you need it immediately. Even when operating over a city those black holes that you thought were parks and are actually factory roofs become apparent.

SilsoeSid

27th Oct 2015, 13:10

P.96Contributary Factors

2. The RADALT and steerable landing light were unpowered after the
second engine flamed out, leading to a loss of height information and
reduced visual cues.

Hmmm;:hmm:

Rad Alt over a built up area.
Would one be able to rely on that height information for judging the height during an auto over the city. Could the preset ht warning (600' +), before the verbal ht warning be a further distraction?

Where to steer the light.
A steerable landing light would be steerable, but steered to where? Perhaps to a position at which the non steerable light, on the Ess bar, is already at? Or maybe straight ahead, but how high, for the flare or for the level?
Where is that steerable light pointing when you switch it on?

efish,

A good point about the dark spaces in built up areas; parks, roofs, car park, woods, cemetery, allotment or waste ground … feeling lucky!

As you goggle and I don't, how close are the goggles to the roof when in the stowed position? (fixed your seats up & down yet? ;) )
If you were to take them off, to relieve the neck muscles, where do you place them? (Surely not on the floor, loose articles and all that)

I once, while landing, had a set knocked off by the GOA in Kuwait that ended up between my feet. Now that was an interesting couple of minutes in the dark hole of a desert :eek:

ShyTorque

27th Oct 2015, 14:26

Not having flown one, I've been quite surprised to read about the intricacies of the 135's fuel system. Having to push fuel around like this at low fuel states on a small helicopter seems to me to be a design "gotcha", if ever there was one.

I'm glad to know that the airframe fuel system of the small twin I "fly" is far less complex, being almost completely gravity fed. A transverse main tank drains naturally into a pair of 100kg supply tanks. A booster pump for each engine picks up fuel from a sump at the bottom of each of the supply tanks. Fuel naturally gets to those sumps by gravity. Unless you go horsing the aircraft around at very low fuel states (and the FM warns you not to), all but 5kgs of fuel gets to the engines. Nose up attitudes aren't a problem because the sumps are near the rear of the supply tanks. If a booster pump fails, the engine driven pump is entirely capable of sucking up its own fuel. This is verified by the after start checks.

If a helicopter gets to a really low fuel state, the pilot will generally be thinking about slowing down, making an approach, then landing. All of those things require a nose up attitude....... Yet on a 135, this is precisely when there is a potential fuel supply problem. Flawed design, imho.

megan

27th Oct 2015, 14:45

Any 412 pilot would be well advised to understand the implications of failure to have the transfer pumps on as well, depending upon the initial the fuel load prior to flight. It's normal to have them on at all times it must be said.

jayteeto

27th Oct 2015, 14:53

No no no no no no no

There are so many people making incorrect assumptions here about the fuel system.

I have 3000 hours on type, the majority being night police. I cycled the switches on hundreds of occasions, it's NOT complicated or dangerous. There SHOULD be plenty of clues well before things get dangerous. There are two pumps to allow for different attitudes and flaring on landing has zero effect because the fuel is in the supplies.

Really, it's not that complicated or terrible as long as the gauges are not stuck on full of course

[email protected]

27th Oct 2015, 15:52

Do you guys make this sh1t up as you go along?
No, you don't read what is written RVDT.

In order to recover the transfer pumps in the main tanks with fuel (which will after a while cancel the F pump caption even with the transfer pump switched off), TC said they used a nod -ie nose down - which moves fuel from the supply tanks (the ones which feed the engines) to the main tanks through the overflow pipes.

Without the transfer pumps running, it would need enough nose up for the fuel to flow back from the main tanks, through the overflow pipes to the supply tanks in order to keep the level in the supply tanks high enough.

It is possible - as the report shows, for more fuel to be shunted forward than expected and for the 4 kg difference between 1 and 2 supply tanks (to prevent both engines flaming out together) to be eroded if the aircraft is manouevered at low speed out of balance.

Fortyodd2

27th Oct 2015, 16:00

Crab,
"In order to recover the transfer pumps in the main tanks with fuel (which will after a while cancel the F pump caption even with the transfer pump switched off)" No it won't - Transfer pump OFF = Caption ON.

"which moves fuel from the supply tanks (the ones which feed the engines) to the main tanks through the overflow pipes."

No, it doesn't. It allows the fuel settled at the rear of the MAIN tank to slosh forward over the front transfer pump - which will clear the caption.
We are talking about a gentle nod - nothing aerobatic.

[email protected]

27th Oct 2015, 16:16

Fortyodd - apologies, you are quite correct, I misread the report about the transfer pumps.

However, the nose down will, even just 5 degrees, according to the report allow fuel from the supply tanks to move to the main tank - doesn't it?

I gather it was widely known that the 'nod' would deplete the supply tanks by a few Kg, but not by as much as the tests showed.

Fortyodd2

27th Oct 2015, 16:20

Crab,
Yes it will - if the level in the supply tanks is high enough to let it do so - where, if the transfer pumps are switched on, they will pump it back again. See the appendix B at the end of the report where it give a good set of illustrations.

efish

27th Oct 2015, 16:22

Goggles in a woolly hat in door pocket works. I'm 5'10" and have my seat fully up and the goggs don't touch the roof in the stowed position. But taller pilots have problems with clearance, our aircraft has marks on the perspex to prove it.

SilsoeSid

27th Oct 2015, 16:25

JayteetoNo no no no no no no

There are so many people making incorrect assumptions here about the fuel system.

I have 3000 hours on type, the majority being night police. I cycled the switches on hundreds of occasions, it's NOT complicated or dangerous. There SHOULD be plenty of clues well before things get dangerous. There are two pumps to allow for different attitudes and flaring on landing has zero effect because the fuel is in the supplies.

Really, it's not that complicated or terrible as long as the gauges are not stuck on full of course

Well said :D

Reely340

27th Oct 2015, 17:00

jayteeto
I have 3000 hours on type, the majority being night police. I cycled the switches on hundreds of occasions, it's NOT complicated or dangerous.But you'd cycle between fwd-pump_ON + aft-pump_OFF and fwd-pump_OFF + aft-pump_ON,
you'd never switch them both off, right?

Is there ANY airborne situation at all, where you'd switch off fwd AND aft transfer pump?

chopjock

27th Oct 2015, 17:22

Is there ANY airborne situation at all, where you'd switch off fwd AND aft transfer pump?

I can answer that, YES. When flying with plenty / full tanks! or when main tank is empty!

SilsoeSid

27th Oct 2015, 17:25

Reely340;
Is there ANY airborne situation at all, where you'd switch off fwd AND aft transfer pump?

chopjock
I can answer that, YES. When flying with full tanks!

If I may take that one with a serious answer, yes when the cautions come on which could be for two reasons;

1. Pump failure.
2. Pump running dry.

skyrangerpro

27th Oct 2015, 17:29

Reely said: "My vision of possible occurrences after reading the final report:

- both supply tanks did falsely indicated full on the CAD
(a 0.5ml (!) water globule at the capacitance based fuel sensors can do the trick, see p. 54, G-NWEM)

- "Low Fuel" Warnings (driven by correctly functioning thermistors), were considered as acting up "shi**y EC".
The were acknowledged as being irrelevant, because of (incorrect) triple "plenty fuel" indication on the CAD.
That is the reason why he flew that final task, although he just had acknowledged the Low Fuel warnings, multiple times!"

I have now read the report front to back three times and I have come to the conclusion that this is the most likely scenario. (I also went back and re-read the 170 odd pages of the first thread which was, errr, interesting).

I found 1.16.2, the G-NWEM incident, (just two weeks after this incident!), shocking. Not only were the supply tanks stuck on full during the ground test but the indicated level of the main tank was depleting with xfer pumps off! It would be easy for none of the crew to question that - (confirmatory bias). It would not prompt a check of the xfer pumps. I note with trepidation that neither would the fuel caution caption come on, and xfer pump captions do not come on if a pump that was switched off after running dry would not come on again if re-immersed. It only comes on after 3 mins of the pumps running dry or after 3 minutes of being switched off while immersed.

Falcon900 said "The AAIB report makes reference to issues with the fuel probes on G-SPAO earlier in the year, and explains that these were resolved. It does not explain whether the faults became apparent while the aircraft was in flight, and who was flying it at the time. I am wondering whether the accident pilot had some history with spurious fuel warnings on this aircraft."

This is a really good point, we are all influenced by our past experience. It is easy to sit in an armchair and say it is inconceivable that 3 people ignored obvious warnings. Firstly, two of those people might have been comforted by a digital blue display more than a red lamp and audible tone (that the pilot had already acknowledged and cancelled several times).

Supposing I said to you the the oil pressure reading for your main rotor gearbox fluctuated wildly then suddenly went to zero, and that you knew that if it was correct you had 8 minutes max before you dropped like a stone out of the sky. Would you stake your life on that reading being wrong? I bet not a single person here would say that they would fly on and try to make base.

But that is exactly what happened here:

Investigation: Faulty filter cover, pilot error caused fatal Marine helicopter crash (http://www.marinecorpstimes.com/story/military/2015/10/25/investigation-faulty-filter-cover-pilot-error-caused-fatal-marine-helicopter-crash/74288256/)

The pilots were influenced by recent MRGB pressure sensor and transducer maintenance work and they were prepared to stake their life on a false indication.

The finding of the position of the prime and xfer pump switches are largely irrelevant, and in fact proven to be unreliable, although the photographic evidence favours at least one prime switch being OFF. I do not believe the pilot has confused the prime and xfer pump switches, for one thing, the caution captions for the prime pumps would have gone on if he has reached up for the xfer pumps in response to a xfer pump caution light coming on.

It has been said that the cause of the accident was the xfer pumps being off. Not strictly true, the cause of the accident was the pilot failing to put them on, their OFF position is the symptom not the cause.

I believe he had conflicting information and unfortunately, possibly due to past experience (someone on the previous thread mentioned running the tanks down to zero on a ground test and the Warning Unit red LOW FUEL 1 and 2 never coming on) chose to ignore procedure and rely on one of two information sources.

Reely340

27th Oct 2015, 17:38

I was just trying to picture a plausible situation, where a +5000h pilot won't look like a crazy risk taking doofus but someone plagued by knowingly unreliable electronics.

RVDT

27th Oct 2015, 17:49

I can answer that, YES. When flying with plenty / full tanks!

Er no - not if you operate IAW the RFM.

Is there ANY airborne situation at all, where you'd switch off fwd AND aft transfer pump?

Yes - if you have exhausted the fuel in the MAIN tanks.

That would of course leave you with the contents of the SUPPLY tanks remaining.
Depending on your operation IFR, VFR or Ops Manual or NAA reserve requirements that may never or rarely happen if remaining within those constraints.

What do you think drove the design with respect to the SUPPLY tank size?

Interestingly should you fit the "FUEL FLOW" option kit - Time to END is predicated only on the contents of the MAIN tank.

ShyTorque

27th Oct 2015, 18:09

Really, it's not that complicated or terrible as long as the gauges are not stuck on full of course

But if there is a gauging fault......

SilsoeSid

27th Oct 2015, 18:36

22:06 - Arrived on task with approx 122 kgs of fuel………... Completed task then went on another task.
[76 kgs in main tank, 46 kgs (25/21) in the supply tanks]

22:09 - Arrived on task with approx 113 kgs of fuel………... Completed task then went to another task.
[76 kgs in main tank, 37 kgs (20/17) in supply tanks]

22:14 - Arrived on task with approx 100 kgs of fuel……...... Completed task and prepared to rtb.
[76 kgs in main tank, 24 kg (14/10) in supply tanks]

22:19 - Prepare to rtb with approx 86 kgs of fuel………...…... Informed ATC of intent rtb, no concerns.
[76 kgs in main tank, 10 kgs (7/3) in supply tanks]

I realise the AAIB can only report the findings, but something was not quite right and it's not, imho, simply the switch positions !

Pozidrive

27th Oct 2015, 20:13

Sid; 22.09 figures have an error in the arithmetic. Could there be a typo somewhere?

RVDT

27th Oct 2015, 21:25

Also interesting that apparently there probably was no F PUMP FWD or AFT CAUTION to prompt selecting the pumps off if the numbers are correct in the reconstruction and flight testing. What prompted the action to turn them OFF? There should have been a CAUTION after they were selected OFF though.

This is also backed up by the amount of fuel found in the aircraft.

Also it is apparent that if you fly a ball width to the right out of balance that you can reduce the differential in the SUPPLY tanks to "not much at all" ~ 32 seconds.

In "balance" the 135 flies left wing down - take a look at the STBY AI installation or the primary AI on level ground. So the differential if flown in balance might actually be greater than 4 kg.

MightyGem

27th Oct 2015, 21:56

I can answer that, YES. When flying with plenty / full tanks!
Err...no. With both pumps off in the cruise, the contents of the Supply Tanks start reducing with approximately 250kgs left in the Main Tank, rendering that unusable unless you raise the nose to spill it through the overflow channels.

kevin_mayes

27th Oct 2015, 22:11

Thats an interesting snippet in the report, page 58 section 1.16.7 concerning the warning unit taking too much current (how much), it implies that a capacitor wasn't spec'd with a high enough working voltage during manufacture, could a situation arise where the current drawn by the failing capacitor tripped a circuit breaker shutting off other systems (i.e fuel sensor) or the extra current drawn pulled the voltage down allowing false readings, some of the wires can be of a small cross sectional area, drawing a lot of current would easily produce a voltage drop, has anybody taken a look at the wiring diagram to see what other systems are connected to the warning panel supply at the same time...?

Never had a tantalum capacitor pack up due to mechanical stress here on things I make, its always due to over voltage, mainly due to fitting the wrong voltage type...

Just my observation.

Kev.

chopjock

27th Oct 2015, 23:22

Err...no. With both pumps off in the cruise, the contents of the Supply Tanks start reducing with approximately 250kgs left in the Main Tank, rendering that unusable unless you raise the nose to spill it through the overflow channels.

Yes, but when main tank is full or nearly full(ok I said plenty), the fuel in the main tank overflows into supply tanks, so transfer pumps are not needed, so they could be switched off. That's what I meant to say.

skyrangerpro

27th Oct 2015, 23:30

A couple more notes I made from the report.

Suppose we take the scenario where everything is supposedly functioning correctly and this is a 100% pilot error incident. Well doesn't that mean that just before the first engine starts sucking air the situation in the cockpit is that 3 people are staring at a CAD that has counted down inexorably to showing fuel of something like 2/77/0 in the fuel display, the primer cautions are allegedly on, we have LOW FUEL 1 and LOW FUEL 2 red captions warnings on the WU and the FUEL caution is also on in the CAD. We know that was the real fuel situation (2/77/0) approximately according to the report, but was it really displaying that? I don't buy it.

Neither do I find it odd that the xfer pumps are off at this stage, given the total amount of fuel on board, it would have been normal for them to be switched off anyway at this stage in the sortie as all the remaining fuel (79 odd) should have been in the supply tanks. So xfer pumps off would not have been a particularly odd configuration, it's most unfortunate that the caption is not triggered when a pump becomes immersed again if it was turned off after running dry.

P23: "When the manufacturer tested the fuel sensors that were returned from the worldwide fleet, for repair, it found about 70% had no fault."

Well helloooo. Did nobody think to question that? Isn't that a bit odd, your customers send in alleged faulty components and 7/10 have no fault! Footprints in the snow, ice that has melted then evaporated are the analogies that come to mind. The evidence has long since left the scene. I would be thinking, 'well unless my customers are crazy, there is something intangible going on here, that warrants further investigation in the field."

The AAIB have executed their remit, but it is solely data gathering and analysis, it is for us to read between the lines. They aren't infallible and neither are the authorities. No doubt they read this forum. They corrected the misspelling of Uddingston in the report (that I pointed out last year) on p6 but didn't correct it on p73. As someone has already pointed out, the new GCH is 1.5nm WEST of Stobcross not East as stated on p28. And there's been a bit of a backflip on the whole primer switch thing when a photo revealed that they weren't in the same position (ON) that they found them in later, assumed and publicised. If that photo hadn't come to light the whole primer/xfer switch pilot mix up bandwagon would probably never have got derailed. Small things but having had nearly 2 years to compile the report and umpteen people proof reading it, I'm surprised considering their exacting standards.

There was also the ghastly revelation in the post mortem that one of the victims was still alive under the heli for up to 17 hours but the scene could not be moved as someone had decided to lock it down for Health & Safety reasons.

Pozidrive

27th Oct 2015, 23:53

Skyranger,

What is the source of information for your last paragraph?

None of the protocols I've ever read prohibit recovery of casualties, even if that means disturbing wreckage/evidence.

SilsoeSid

28th Oct 2015, 01:09

The low fuel action is to land within 10 minutes.
At that stage the low fuel warnings would have both be on at about 22:09 hrs, with the fuel readings being 20/76/17. (36 kgs) This is the time at which they were about to commence a job, they then did another, followed by the start of the trip back to base.

Why would they do all this while being presented with;

LOW FUEL 1...................LOW FUEL 2

PRIME PUMP...................PRIME PUMP
......................FUEL
..................F PUMP AFT
..................F PUMP FWD

......20…….........76…….........17

(Possibly not the prime pumps but maybe)

Interesting to note that on three occasions when the low fuel one warnings were acknowledged, the caption also cleared.

After the normal start-up sequence warnings had cleared, the next recorded snapshot showed that a low fuel 1 warning (caption and audio) was triggered, relating to the level of fuel in the supply tank cell supplying the left engine.
The audio attention-getter was acknowledged and then the caption cleared. The low fuel 1 warning was triggered again, the audio attention-getter was acknowledged once more and the warning then cleared for the second time.
The next warning was low fuel 2, relating to the level of fuel in the supply tank cell supplying the right engine. The audio attention-getter was acknowledged and the caption on the WU remained for the rest of the flight.
This was followed by another sequence of a low fuel 1 warning, the audio attention-getter being acknowledged and the caption clearing. A further, final onset of this warning was followed by the audio attention-getter being acknowledged and the warning caption remaining for the rest of the flight.

But everything was working and indicating ok .... wasn't it !

page 95.
No significant pre-impact technical defect was identified in any part of the aircraft or its systems.

Mechta

28th Oct 2015, 01:11

Skyrangerpro wrote:

P23: "When the manufacturer tested the fuel sensors that were returned from the worldwide fleet, for repair, it found about 70% had no fault."

Well hello. Did nobody think to question that? Isn't that a bit odd, your customers send in alleged faulty components and 7/10 have no fault! Footprints in the snow, ice that has evaporated are the analogies that come to mind. The evidence has long since left the scene. I would be thinking, 'well unless my customers are crazy' there is something intangible going on here, that warrants further investigation in the field.

I'm glad you noticed that too. As I recall Eurocopter (as they were at the time) said,

The issue, discovered by Bond Air Services, appears to be that the probes are indicating a fuel level higher than actual. Investigations showed that the incorrect signals that the probes transmit to the indicator may also inhibit the amber “fuel caution” light. Tests confirmed the problem starts with water contamination. As of December 23 (2013), 264 sensors had been tested. Of those, 12 needed to be cleaned but were fully functional afterward, while two failed and needed to be replaced. Meanwhile, the “low fuel” warning system is independent and remains reliable, Eurocopter said.

EC135 Faces Fuel Sensor Fault | Business Aviation News: Aviation International News (http://www.ainonline.com/aviation-news/business-aviation/2013-12-26/ec135-faces-fuel-sensor-fault)

That means twelve sensors which should have been working were not, because they were contaminated with something.

Pozidrive,

None of the protocols I've ever read prohibit recovery of casualties, even if that means disturbing wreckage/evidence.

My interpretation of the report was that the accident scene was so unstable due to the danger of the wreckage collapsing into the Clutha basement, that it was not safe to extract the injured person until the basement ceiling had been shored up.

G0ULI

28th Oct 2015, 02:04

Health and Safety and scene preservation have nothing to do with the recovery of victims. Sometimes the risks are too great to proceed without specialist equipment or shoring, which takes time to arrange. Just diving in will end up with more casualties among the rescuers as debris shifts and collapses and will almost certainly hasten the demise of any victim(s).

The fuel sensor issues and possible misleading display of fuel levels are to some extent a red herring. Fuel gauges in all aircraft are notoriously trouble prone and are only an indication that some fuel is probably in the tanks. I was taught to manually dip the tanks to check fuel levels before every flight and calculate maximum endurance accordingly and subtract 30 minutes. That was the point I should be back on the ground, no matter what.

Even if the fuel had been in the supply tanks and not the main tank, the helicopter would have landed back at base well below the mandated minimum fuel load. What excuse would have been used to explain that? What sanctions would have been taken against the pilot, if any? Could the severity of any penalties for breaching minimum landing fuel have been preying on the pilot's mind? That would certainly be a distraction especially with doubts already being raised about fuel gauge accuracy in the EC135.

Maybe accepting the last tasking was simply resignation that the helicopter was below minimum fuel anyway, and it was only a couple of miles back to base. Might as well get hung for a sheep as a lamb.

skyrangerpro

28th Oct 2015, 09:01

Families hope FAI will finally give answers over Clutha crash | News | The National (http://www.thenational.scot/news/families-hope-fai-will-finally-give-answers-over-clutha-crash.9138)

“An FAI should give me answers as to why my father was left under that helicopter alive and according to the post mortem report he was alive for over 17 hours after the crash.

“I believe my dad could have been saved and I want to know why he wasn’t freed while he was still alive.

DrinkGirls

28th Oct 2015, 09:34

Since the accident, a lot more has been learned about the 135 fuel system. Some of you experienced operators commenting here don't realise yet that what you thought was correct is in fact not true. Until recently, I would have agreed with you.
The main fact is about spillage between the main and supply tanks if you pitch the aircraft. Whilst there can be some transfer, the tanks are not like the diagrams, they have gaps between them. Any transfer is a trickle only and is not significant. Therefore pumps need to be on, even if the main is full.

Second, when the supply tanks are full to the brim, they hold more than the gauged 90kg. The excess fuel is added to the main tank indication. The 90kg amount is basically for certification (ish). This affects in 2 ways.
First, when the actual main tank is empty, there will be a small amount of fuel showing on the main gauge.
Second, when carrying out the supply tank drain ground run, after you turn the transfer pumps off, the main tank continues to show a reduction for a few minutes. Then the supply tanks start to reduce. This is that little bit of fuel 'above' the supply tanks burning off. Initially, pilots thought that fuel was still transferring.
This is not my opinion, this is fact

skyrangerpro

28th Oct 2015, 10:42

Even if the fuel had been in the supply tanks and not the main tank, the helicopter would have landed back at base well below the mandated minimum fuel load.

From the report the fuel policy that was in place at the time was:

"2.1.3 Fuel policy

The PAOM Part 1 provides guidance for fuel planning, advising that fuel for
30 minutes at endurance speed (burning 170 kg/hr) should be included for a
flight over a non-hostile environment at night, in addition to fuel for start, run-up and taxi allowance, as appropriate, and the duration of the task.

At the time of the accident, the operator’s Operations Manual stated that the
Final Reserve Fuel IFR was 85 kg, with a Minimum Land on Allowance (MLA)
of 40 kg, and that:

‘Company policy is that the aircraft should not land with less than
60kg of fuel in the tanks.

If it appears to the aircraft Commander that the Final Reserve Fuel
may be required, a PAN call should be made. If the Final Reserve
fuel is then subsequently reached, this should be upgraded to a
MAYDAY.’

Since the helicopter had 76 kg of fuel on board at the time of the accident, the pilot might have been expected to make a PAN call, upgrading it to a MAYDAY on reaching the Final Reserve Fuel IFR, if he was aware of the fuel state. Again, due to the lack of evidence that might otherwise have been provided by cockpit voice and flight data recorders, the investigation was unable to determine the reasons for this apparent omission."

No surprise that with three different numbers in the mix there, that these policies were updated shortly after the incident to clarify:

"Following the accident, the operator amended their Operations Manual
procedure on fuel calculations, replacing the Minimum Land on Allowance
(MLA) with Final Reserve Fuel (FRF), and increasing the VFR and IFR/night
FRFs to 90 kg."

Now it's easy to sit in an armchair with a calculator and see that it is tight starting with 400kg and running for 1hr 40 (Both 3kg/min and 3.3kg/min have been used as quoted consumption figures, dependant on task type). But IF the display was stuck at 45/x/49 where x is some number, then it is not clear to me that the pilot would think that he is 'well below' any of those levels. What measure does he have other than the CAD display over rough mental arithmetic in his head to cross check?

ShyTorque

28th Oct 2015, 11:24

(Both 3kg/s and 3.3kg/s sec have been used as quoted consumption figures, dependant on task type).

I would check those figures again, if I were you.

SilsoeSid

28th Oct 2015, 11:47

Drinkgirls;

Since the accident, a lot more has been learned about the 135 fuel system. Some of you experienced operators commenting here don't realise yet that what you thought was correct is in fact not true. Until recently, I would have agreed with you.

First, when the actual main tank is empty, there will be a small amount of fuel showing on the main gauge.

This is not my opinion, this is fact

http://i52.photobucket.com/albums/g11/silsoesid/main%20zero_zpsyovyg7iv.jpg

DrinkGirls

28th Oct 2015, 12:04

Badly explained by me Sid. What I am trying to say is that when the last drop of fuel is pumped from the main tank itself, the display still shows a few kg of fuel in the main tank display. This is because a small amount of fuel ABOVE the supply tank is actually displayed as main tank contents.
This then is used until we reach your picture.
Really, this is true and not Pprune guff, it's from Airbus

You have assumed that when I said "when the main tank is empty", I meant empty on the gauges

DrinkGirls

28th Oct 2015, 12:13

In your picture, it implies that once the main tank is above the "fence" fuel spills into the supplies, it doesn't. The tanks are separated with overflows back to the main. Airbus have issued an updated schematic in which it all makes sense. This is where we had it explained about the metered fuel. The supply tank actually holds more than 90kg, it is DISPLAYED as 47/43 (ish) and a bit is added to the main contents as well.
Really, it IS fact

SilsoeSid

28th Oct 2015, 12:31

You have assumed that when I said "when the main tank is empty", I meant empty on the gauges

How could I possibly assume that? You were quite clear in that you were saying that when the actual main tank is empty, the gauges will still indicate a quantity.

More seriously though, what you are suggesting Drinkgirls is that the tests that were completed on the manufacturers EC135 Articulated Fuel System Test Rig, from page 54 in the report, were incorrect.

"The supply tank actually holds more than 90kg, it is DISPLAYED as 47/43 (ish) and a bit is added to the main contents as well.
Really, it IS fact"

page 59;
One test point replicated the orbit at Dalkeith, as much as possible. The orbit was flown at 30 kt, with an indicated nose-up attitude of 5-7°, in level flight. The fuel on board at the start of this test consisted of 47 kg and 43 kg in the left and right supply tank cells respectively, with 97 kg in the main tank. After four minutes, the indicated fuel in the left and right supply tank cells remained the same and the amount in the main tank had reduced to 82 kg.

(Main tank started with 97 kgs, 4 minutes later had 82, consistent with a 3.5 kg/min burn rate.)

DrinkGirls

28th Oct 2015, 13:03

Drinkgirls;

Page B-3

http://i52.photobucket.com/albums/g11/silsoesid/Screen%20Shot%202015-10-28%20at%2012.56.50_zpscjpxxi4y.png

Thank you, that diagram is the one. It explains what I meant far better than I could.

SilsoeSid

28th Oct 2015, 13:06

If only you could have described what you meant better :ok:

Mmm, where's that gone? Pic is on page B-3
https://assets.digital.cabinet-office.gov.uk/media/5628ea4ded915d101e000008/3-2015_G-SPAO.pdf

DrinkGirls

28th Oct 2015, 13:24

I know, I know! I'm a divvie. But what I was trying to say is in agreement with you, people are commenting and have no idea on reality. It is frustrating, just like a certain chinook thread.

SilsoeSid

28th Oct 2015, 13:59

Just to highlight what the pilot sees when the Prime Pumps are switched on;

8_KvlaIYyIo

Best seen on the youtube site in full screen, in a darkened room :ok:
https://www.youtube.com/watch?v=8_KvlaIYyIo

chopjock

28th Oct 2015, 14:01

DrinkGirls,
In your picture, it implies that once the main tank is above the "fence" fuel spills into the supplies, it doesn't.

How does fuel get into the supply tanks during fuelling?

Flying Bull

28th Oct 2015, 19:14

Hi Chopjok,
not quite sure about the 135 - but in the BK117 you switch the transferpumps on, to get the feeder tanks filled.....
Wich you seldom need, cause you normaly land with them filled....

TeeS

28th Oct 2015, 19:40

Hi chopjock

The refuelling point is into the main tank. This will fill the main tank until it reaches the level of the two pipes that connect the main tank to each of the supply tanks; at this point, fuel will 'overflow' into the supply tanks and fill them. The exceptions to this are:

1) If the battery is on and transfer pumps are selected on, the FWD transfer pump will be filling both supply tanks during the refuel

2) If the battery is on, shed bus switch is activated or ground power is applied and transfer pumps are selected on, then both transfer pumps will be filling both supply tanks during the refuel

Ignore any mention of a 'fence' in this process - the fence exists between the two supply tanks and happens to be at approximately the level of the two connecting 'overflow' pipes.

Cheers

TeeS

RVDT

28th Oct 2015, 20:08

Information Notice AHD EC135 IN 2693-I-28

Starts at page 111 in the report pretty much explains it.

With respect to your dialogue it pretty much covers it.

Wageslave

29th Oct 2015, 00:15

It is frustrating, just like a certain chinook thread.

I've been thinking this for a long while and I hope we are grown up enough to consider the following without taking it a personal criticism of anyone. Far from that it is intended as an overview of human frailty rather than that of individuals.

Someone flies beyond their ultimate endurance as quantified by consumption over time and even when faced with a drawn-out barrage of low fuel indications carries on tasking and falls out of the sky in a failed attempt to achieve the most fundamental of a helicopter pilot's emergency manoeuvres; autorotation. This is, by anyone's standards utterly inexplicable yet it happened.

And everyone who knew him said "he was such a brilliant pilot he couldn't possibly have done this..."

Someone flies VFR into fog, returns towards base and while apparently texting (!) on his phone in IMC in controlled airspace while under SVFR tries to carry out an unplanned diversion into somewhere without visual contact and hits a crane...This is, by anyone's standards utterly inexplicable yet it happened.

And everyone who knew him said "he was such a brilliant pilot he couldn't possibly have done this..."

A mil heavy flies in marginal VMC into a mountain that they knew was there and was planned into their nav kit (the rights and wrongs of whether another type should have been used is irrelevant) This is what happened. This is, by anyone's standards utterly inexplicable yet it happened.

And everyone who knew him said "he was such a brilliant pilot he couldn't possibly have done this..."

A superbly IFR equipped 2 pilot corporate twin ploughs onto the ground 600m from it's take off point in 20m vis. Thew crew apparently couldn't perform a towering IFR departure - had never been taught??? The company involved already had similar previous. This is, by anyone's standards utterly inexplicable yet it happened.

And everyone who knew him said, "he was such a brilliant pilot he couldn't possibly have done this..."

How many other cases can we provide to support this theory?

How many pilots have shut down the wrong engine, and all their colleagues indignantly cry,

"he was such a brilliant pilot he couldn't possibly have done this..."

How did 3 Korean pilots inc. at least one line trainer drag the keel of a 777 over the round-down and damn near scribble 300 people? This is, by anyone's standards utterly inexplicable yet it happened.

"they were such experienced pilots they couldn't possibly have done this..."

A Hawker Hunter ploughs into a main road after a manoeuvre involving a bizarre cranked half cuban entry into a loop or somesuch,

And all who knew him protested "he was such a brilliant pilot he couldn't possibly have done this..."

The Display Safety Officer at a show at Duxford, .... He'd just briefed everyone else not to do it, then promptly did it himself. This is, by anyone's standards utterly inexplicable yet it happened.
And everyone who knew him said "he was such a brilliant pilot he couldn't possibly have done this..." But he had.

And a dozen or more others.

Yet in each case they did do it, and in each case without the tiniest shred of evidence - evidence mind you, not emotion, evidence - or even a credible theory - to suggest anything but pure pilot error.

Isn't it about time we grew up enough to accept that even the best of pilots can and occasionally do make the daftest seeming mistakes? It may hurt us, by association, to admit this as it infers fallibility in the rest of us which is never a comfortable admission, but the reality is that this simply is the case in a surprising number of accidents.

Every time there is an accident it seems that max effort is put into "proving"the pilot - that infallible God-like being made in the image of the rest of us, could not possibly have had anything to do with it even when it is abundantly clear that there is no shred of evidence for anything else.

I do not accept legal quibbles re "proof beyond reasonable doubt" which in today's wacky logic means "proof beyond any other statistical possibilty" which isn't the same thing, is reason to deny the likelyhood of the cause - to do so is to bury our heads in the sand and deny the possibility of human error which is repeatedly proven to be by far the most likely cause.

From a position of both logic and such evidence as we have from previous events where no other feasible cause is found it seems obvious beyond reasonable doubt that the rational thing is to question the pilots's actions or inactions.

In this particular case there is apparently no suggestion of malfunctions (as opposed to design errors) within the fuel warning nor any other system system so what explanation can there be except that the pilot, for some unknown reason, continued the flight beyond any reasonable rationale.

We'll never know that rationale, we probably could not even know it had a flight data/voice recorder been fitted but even when every helo, glider and microlight is encumbered with one with one I think we can be assured that every now and again someone is going to fly into predicted cumulo granitus, blindly clobber a construction crane or just try to fly for an hour on fifty nine minutes of fuel in the hope that - well - what?? We'll never know, except that he did.... It's simply human nature. And a mystery. Mandatory recorders will almost certainly reinforce the fact that many, if not most accidents are not related to technical malfunctions at all and though in some cases we'll gain clues from what is said or recorded we'll still be totally flummoxed by the greater proportion.

I don't think we advance the science of air safety by resolutely denying the likelihood of pilot error simply because he "was a good bloke" and we think him to be a "good pair of hands" and therefore incapable of error - or rather that in the reflected limelight we prefer to think ourselves as infallible as we wish him to have been...
It's a bit of a generalisation but statistically a pretty sound assertion that if it looks like a duck, flies like a duck, quacks like a duck than it probably is a duck and thus most likely didn't fly into the ground in vmc by virtue of some inexplicable and unreproduceable avionics failure or fuel system design fault.

A desire to absolve fellow pilots of responsibility for an accident is all very commendable but when blindly continued - as so often happens - in defiance of all evidence it begins to look like no more than tribalism, self indulgence or nepotism. Or a kind of transferred self-denial. And that is a blinker that Aviation Safety could do without.

Doubtless I will be flamed into ashes now for daring to say such heretical things, this concept will not be to everyone's taste, but can you fault the general logic?

G0ULI

29th Oct 2015, 00:35

Wageslave
You make a good point. The AAIB reports tend to focus on the mechanics of flight and problems with the aircraft, rather than the pilot. Where no mechanical issues are found, then it is put down to pilot error. But, there is seldom any detailed analysis or report about the personality of the pilot, relationship problems, and other issues that may have influenced his or her behaviour at the time of the accident. At best we get, the pilot was well rested having flown x number of hours y days before the accident flight and had a class 1 medical. No drugs or alcohol were found in the body. Often the reason for this is cited as not wishing to intrude, embarrass or further distress grieving relatives. The German Wings crash was a notable exception to this general rule.

A common factor in many accident flights is that pilots are (or feel) pressured into making a flight when their own best judgement should be screaming NO! If the man with the money says fly, you fly. Good well paid flying jobs are hard to come by.

Fortyodd2

29th Oct 2015, 01:00

Wageslave,
Well said.

Wageslave

29th Oct 2015, 01:26

The Boss Man saying "FLY!" was undoubtably a big factor in two of the scenarios I mentioned, but I feel that this accident went deeper than that.

What on earth makes someone carry on flying with the whole warning panel is screaming "low fuel" and the stopwatch is backing that up?

Was it "Oh, we'll just squeeze it back home, it'll be OK and we'll keep shtumm" or simply shocked denial of all the evidence and suppression of the facts, or some sort of fear-induced bravado? Maybe even simple flat denial. Panic perhaps? Low fuel! Sheeeet! and perhaps continue the motor task but freeze mentally? We can't afford to reject any of these possibilities.

Lack of rest, family troubles or the Boss saying "Fly!" are all stressors and decision making influences but I feel that something much deeper, much more fundamental to the task occurred, something more akin to target fixation perhaps. A Professional pilot on a complex mission in challenging conditions getting so wrapped up in the task that he allows the tactical situation to overwhelm his judgement? This is far beyond mere fatigue or boss-induced stress, this is a kind of hypnosis or tactical tunnel vision that obscures the rest of his judgement? I don't know, I just can't see a scenario that is remotely familiar to me that could explain it, and lets face it, the engineers can't explain it so like it or not it is most likely to be down to something on these lines..
Look how those A300 pilots flew repeated approaches to Mogadishu last week and finally ran out of fuel downwind - it's not as if they didn't see it coming with each successive go-around, but something gripped their minds so comprehensively that they finally launched into the luft with only enough fuel for half a circuit. How could that be? Yet they did it. Their broad tactical view had somehow been compressed into looking down a toilet paper tube, and ultimately down one with a plug in it. Yet they still flew on imagining a picture it couldn't possibly have shown them. They were far from the first, and they certainly won't be the last. CRM doesn't begin to explain how this sort of thing happens despite it being a recognised cause of accidents. Why is that? It is clearly a not infrequent occurrence.

We'll never know but I'd bet Clutha was sometjhing similar. I'll be looking to the psychologists rather than engineers for an answer to this accident now, and I'm not holding my breath.

I'm just so sorry the relatives were mislead into expecting that the AAIB report would provide definitive answers when it was pretty clear from the start that it could not. I hope and pray they are not similarly deceived by the media over the equally fallible powers of the Fatal Accident Enquiry which, in the absence of any new facts, has no more hope of providing an answer.

DOUBLE BOGEY

29th Oct 2015, 04:41

Wageslave - two very insightful posts well written.

Sir Niall Dementia

29th Oct 2015, 08:18

Wageslave;

Well written, and saying what I believe so many are thinking. You have concerns about being flamed, you shouldn't. I don't believe anyone can argue such concise and well thought out posts.

SND

ShyTorque

29th Oct 2015, 08:19

Although I see the point of view put forward by "wageslave", I would never agree to the principle of every aircraft being fitted with a CVR.

Why not? Because not all aircraft are used for public transport and as a general principle, I'm against a surveillance society.

skyrangerpro

29th Oct 2015, 09:16

The whole premise of twin engine operations is based on probability. The probability of the first engine failing (P1) for whatever reason (fuel starvation etc), and the second engine failing (P2) on any given sortie is deemed to be so infinitesimally small (P1xP2) that the operation of twin engine craft are seen as a better option than single engine in many applications.

The trouble with this theory is that this incident has proved this isn't so and that once the pilot places the craft into a certain configuration (xfer switches off), for whatever reason, and leaves them off when they need to be back on (for whatever reason) after a certain period of time, P1 will become 1 (certainty), but worse, P2 will also become 1.

The fact that millions of hours have been accumulated in this type with no incident is irrelevant, when you are dealing with low probabilities, you have to wait millions of hours for something to happen. It seems a weak design to have something that needs to be in the correct position for continued and safe flight, out of direct line of sight, unlit and next to other switches of a similar look and feel.

If it really is impossible to design a pump that is able to be put in an automatic mode and we are stuck with xfer switches that are dependant on pilot management, they should at the very least be in direct line of sight and even better, positioned right below the relevant captions in the WU.

maddmatt

29th Oct 2015, 10:30

ShyTorque

CVR's have nothing to do with with big brother watching, if they help investigators identify root cause of an accident why would you not want them? This current thread is a prime example of an accident that will leave loads of unanswered questions, speculation and second guesses.

It will not provide closure to those affected by the accident and it will not help the industry's ability to improve operational or emergency procedures, or pilot training.

There has been a lot of comments on this thread, some I agree with and some i think are pure fantasy and made with little knowledge. Wageslave pretty much summed it up. There are facts and they are unanswerable questions

Reely340

29th Oct 2015, 11:45

skyrangerpro: If it really is impossible to design a pump that is able to be put in an automatic mode and we are stuck with xfer switches that are dependant on pilot management, they should at the very least be in direct line of sight and even better, positioned right below the relevant captions in the WU. A friend of mine, who was assisting a HEMS Corp. fleet admin, claimed EC135 come (came?) with different types of transfer pumps. There are pumps (model years?, configurations?) that can run dry up to 5 min only, then there are those we're talking about which can run dry for 20min (AAIB report) and apparently there are transfer pumps (in the BO105 for sure) that noone ever has to switch off, no matter how low the level in the main tank is.
N.B. Said company owns multiple BOs and one EC135, so they should know.

Anyone here knowledgable about types of EC135 transfer pumps?

Reely340

29th Oct 2015, 12:19

There is hope, at last:

The manufacturer is also developing fuel quantity sensors that are less susceptible to water contamination, expected to be available in the fourth quarter of 2016. For the next update to the EC135, scheduled for certification next year, Airbus Helicopters is simplifying operation of the fuel transfer pumps to remain ON at all times during flight without dry-run indication warnings, reflecting the improved dry-run capabilities of new-generation pumps. :ok:

And of course where there is light there has to be shadow:
However, this change is not proposed for the current EC135 fleet, as the existing fuel pump caution signal does not differentiate between a dry-running pump and pump blockage.:{ :ugh:

Both quotes taken from Final Clutha crash report leaves many questions unanswered | Vertical Magazine - The Pulse of the Helicopter Industry (http://www.verticalmag.com/news/article/FinalCluthacrashreportleavesmanyquestionsunanswered)

ericferret

29th Oct 2015, 13:01

Dry running pumps have been available for years. Jet pumps (venturi fuel driven pumps) as used in the AS365/EC155 and others. In this case having Jet pumps in the main tanks would mean that the pilot had no need to worry about pumps running dry. As long as the boost pumps (replacing prime pumps) in the supply tank were operating then fuel would transfer.

I remember an engineer friend of mine discussing the unecessary complications built into modern design. He described a modern system to regulate water flow and level, describing level sensors and controlled valves. He concluded with of course you could always use a ballcock!!!

SASless

29th Oct 2015, 13:11

Why not? Because not all aircraft are used for public transport and as a general principle, I'm against a surveillance society.

I like to know why accidents like this one happened in the first place. In the second place if we knew why this one occurred we might just be able to prevent others from dying.

Public Transport or not....some very innocent people died as a result of this crash.

How many have to die before your desire for privacy is trumped?

andyy

29th Oct 2015, 13:57

By Wageslave:

"I'll be looking to the psychologists rather than engineers for an answer to this accident now, and I'm not holding my breath".

Good posts, Wageslave, and I think you are right not to hold your breath.

AAIB is a largely engineering led organisation and, I understand, do not have any Human Factors specialists on the team.

MrsY is a Human Factors specialist involved in accident investigation and was shocked by the lack of Human Factors knowledge/ experience/ interest after meeting with AAIB personnel.

HeliComparator

29th Oct 2015, 14:00

How many have to die before your desire for privacy is trumped?

Probably not as many as had to die to achieve the personal freedoms and privacy we enjoy these days.

ShyTorque

29th Oct 2015, 14:14

SAS,

There are many car accidents, far more than those in aircraft, which injure and kill members of the public, thousands of them. So, are you prepared to have a CVR in your private car?

Your private boat? People have boating accidents, some fatal.

In your private house? There are huge numbers of fatal accidents in the home.

Where do I draw the line?

CVRs in all PT aircraft, by all means, but not in all aircraft. In any case, the use of them in private aircraft would be totally unregulated, and regulations regarding their usage unenforcable.

I once worked for a non AOC operator who had a CVR retro-fitted. No big deal until we discovered he was regularly reviewing the aircraft CVR tapes. Nothing to do with accident prevention. He wanted to weed out those speaking against the company.

Helicomparator,
Probably not as many as had to die to achieve the personal freedoms and privacy we enjoy these days. Excellent point. I think the USA should review its gun laws first...many lives to be saved there, too. How many have to die before "the right to carry" is trumped?

SASless

29th Oct 2015, 14:19

If an Oil Company can require CVR's why should the Police not be able to do the same thing?

Even BALPA is backing down from their stance on releasing CVR Recordings it would appear from recent news.

Why the concern over a lack of privacy at your work place?

It is not your home, your car, your girlfriend's flat, it is your place of work.

If you had a CVR....would you do anything any different than you do right now?

ShyTorque

29th Oct 2015, 14:21

So you think we should just rollover in total surrender?

SASless

29th Oct 2015, 14:30

I have flown many helicopters with CVR's and have absolutely no concern about them being used.

Perhaps, I know when to make snarky comments about my employer and realize the Cockpit is not the place to do that.

I damn sure know that is not the place when there is a CVR.

Yet, If I stick to the business of flying the aircraft in compliance to all the Rules, Regulations, SOP's, Checklists and the like then I am quite happy for the Boss Fellah to check up on me. If I get out of step for some reason i am quite comfy explaining why I did what I did.

If I snuffed it in a crash I would want the CVR to clear me of any intentional misconduct and prove me to be as much a Victim as my passengers.

I bet if you asked Dave's Family and Friends....they would tell you they would like to know the answers to the many questions still remaining about how this Tragedy occurred....having a CVR probably would provide many of those answers.

On a lighter note.....

Borrowing a post from Ericferret in the Military Aviation Forum about the lack of Commonsense in the US Military.....

Currently North Sea helicopter crews are wearing bright orange emmersion suits with reflective strips. To go out to the aircraft they have to wear a high viz. No hope whatsoever for the survival of the human race with this level of idiocy.

Shy.....Yes.....I think you lot have rolled over and surrendered.

Thomas coupling

29th Oct 2015, 15:53

Wageslave, I don't think everybody is skirting around the real cause of this accident. I for one (and before the results came out) felt that even if there was a technical hitch with the fuel system on this a/c, the pilot had mishandled the subsequent EOL.
Since the report, I have re-inforced these views.

I am onboard with your views.

To ERR is to be human and people need to understand that occasionally the soft fleshy bit at the front of the aircraft - malfunctions, just like inanimate parts do.

CVR and FDR's have been long overdue in the police world. We talked about them in the late 90's. The CAA should have mandated them over a decade ago.
I FULLY expect there to be a statement shortly in this regard.
Either black boxes or twin pilot. For police ops.

ericferret

29th Oct 2015, 16:27

and Air Ambulance?

FH1100 Pilot

29th Oct 2015, 17:39

Now that the AAIB report is out and digested, and the goofy fuel system of the EC-135 has been explained, we've come to a point where we have a pretty clear idea of *what* happened, if not the *why* of it. And I don't think we'll ever know exactly.

But I have an idea!

First of all, I think the pilot was intentionally flying the main tank down to zero, using the fuel in the supply tanks as his reserve. "Legal" or not, within SOP or not, that's what he was doing. He was really close to the base, and I'm sure (conjecture here) that one way or the other he was landing as soon as that particular task was complete. And 78kg was probably "close enough" to his required reserve to be acceptable.

Heck, I've done that in a 105, albeit inadvertently: On a long flight I misjudged the fuel required and ran that dang Main down to zero knowing I had twenty minutes in the Supplies. We were close to our fuel stop, but even so when I saw that supply tank needle start to move down I was one tense piloto. The mechanic who was flying in with me from offshore was not a happy camper.

So what caused the EC-135 pilot to shut *both* transfer pumps off? Well, it has to do with these "rigid-rotor" helicopters: The cabin attitude between hover and cruise changes a lot! And we know that the fuel in the main tank moves around a lot between cruise attitude and hover attitude. The fore and aft transfer pumps become uncovered...then they get covered again. Speed up to cruise...slow to loiter...speed back up to cruise...etc. At low fuel levels, in forward flight the aft transfer might be sucking air. Come to a hover and the forward transfer pump unports.

These were not long legs from one tasking to the next. Perhaps Dave just got tired of the captions coming on and off and just said, "Screw it," and turned both transfer pumps off, intending to turn them back on before the supply tanks got "too" low. My guess is that when he finally did reach up to turn the transfer pumps back on he inadvertently got the "primes" instead. Hey, it's dark, and they're right next to each other. Who among us has never hit the wrong switch at night? My hand ain't up.

I'll bet that first engine failure caught him completely by surprise. Below 1,000 feet there's not a lot you can do, troubleshooting-wise: Pitch for best single-engine speed and set OEI power. By the time it was all sinking in, that second engine quit. "What the...?" He did the best he could, I'm sure. But he didn't have much time. It was all over eight seconds after the second engine quit. Not a whole lot of time.

Although I've voiced my educated guess, I cannot think of a single genuine reason a pilot might want to shut *both* transfer pumps off in flight. That is probably the biggest unanswerable question of this accident. But hey, we're all humans here.

So in the end, I guess I agree with Reely340 and others. The transfer pumps in the EC135 ought to have an "auto" setting that will take their operation away from the pilot.

Sky Sports

29th Oct 2015, 18:40

I'm only playing devils advocate here, but here we go anyway.

There is a train of thought that suggests pilots should have things to do, should be kept busy, to concentrate the mind. Automation can be a wonderful thing in other walks of life, but in aviation it can lead to inactivity and a loss of concentration and system status.

Yes, the transfer pumps could be automated on the 135, giving the pilot less to do, but what then? If we stick with the 135 he/she could find themselves with enough time on their hands to start messing around with twist grips/training switches and knacker two engines.

On one of the early 135's, the NHP with nothing to do wondered how much effort was needed to press the fuel shut-off button. You guessed it. He pressed the button and one engine spooled down in flight.

The switches were modified with the cross shaped metal guards. This lead to another pilot in a boring cruise to wondering if he could get a pen between the guard squares. You guessed it. He could and the engine spooled down. That's why the latest mod is a Perspex guard.

Away from the 135, the classic example is Air France flight 447. A trans-atlantic flight that was so automated that the aircrew only had about 3 minutes of work at each end of the flight. And we know what happened to that.

So while we all like to do less for the same money, in some cases there is a really good reason to keep people busy.

ShyTorque

29th Oct 2015, 18:59

I bet if you asked Dave's Family and Friends....they would tell you they would like to know the answers to the many questions still remaining about how this Tragedy occurred....having a CVR probably would provide many of those answers.SASless, Davy Traill was one of my ex RAF colleagues.

Anyway, I'd agree with your quote above. It was a public transport flight. I wrote that I would not be happy about CVRs on every aircraft. Had you read my initial post on this (#195) properly and in context, you would have already realised that I have no objections to CVRs on PT aircraft.

ShyTorque

29th Oct 2015, 19:03

Sky Sports

So while we all like to do less for the same money, in some cases there is a really good reason to keep people busy.There is always something job related to occupy police pilots on task! And there is only one pilot.

nigelh

29th Oct 2015, 19:06

If you are all so worried about privacy then why not have the recorder sealed and only the AAIB can open it in the event of an accident ?? That way we can all continue having a crafty cigarette and slagging the boss off without worry ??

[email protected]

29th Oct 2015, 19:07

I think a police pilot, at night with busy tasking and limited endurance, has quite enough to do without fannying around with fuel transfer pumps.

A better design in the first place would have removed the dick-dance required to manage the fuel system

However, following on from wageslave's comments - there is an adage in the instructional world that 'it's the good student that will be the one who tries to kill you'.

Everyone runs out of capacity and talent at sometime and the better skilled and more competent often get themselves into stickier positions before that happens.

Unfortunately, running out of talent for someone who has some is frequently a 'cliff-edge' event rather than a gradual decline, especially if their perception is that they are operating inside their comfort-zone.

MichiScholz

29th Oct 2015, 19:25

Even when there are thousand of flight hours logged with this type of helicopter, from my point of view it must be said, that there could be a better design of the essential fuel system.

1) placement of prime pump switches right beneath the transfer pumps. The prime pumps are only needed during startup as far as I know, so why not placing them riight beneath the fadec switches, or integrate them in the fadec startup logic?

2) Unreliable display of FUEL quantity in the supply tanks. At least the fuel low is now independent from the sensors. Fuel low - land as soon as possible!

3) Expecting 4 minutes on fuel starvation get cut down to a few seconds, I think only a few, maybe nobody can handle such an emergency during night, but maybe this scenario should be trained in a simulator.

Wageslave

29th Oct 2015, 22:36

The big question, surely is CVR or FDR, or both?

I can see no rational objection to either on moral or ethical grounds. I've flown many thousands of hours with both and never gave it a moment's thought. If you don't trust the management then erase the CVR after landing as you are entitled to do.

But surely a CVR is of limited use at best i the single pilot environment unless pilots are given to talking to themselves whereas a FDR is far more valuable.

What is also certain is that the feelings of relatives should play no part whatsoever in the decision to fit, these must be for air safety reasons and air safety reasons alone. We cannot allow monitoring to become established in the name of 3rd party emotions or we'll be heading down a very dark and hazardous one-way street.

3rd party emotions are already becoming far too big a factor in the media over this particular accident and the sooner it is made clear that the AAIB report has no remit to answer there the better. This isn't being harsh, it is a necessity to keep professional rand safety requirements quite separate from personal feelings and inappropriate expectations. They do not make a useful mix, quite the contrary. Vide the distasteful hue and cry about the Shoreham Hunter pilot "still walking around" "without having been grilled by the police yet", a quote that chills me to the bone in it's unjust and aspiring vindictiveness and implied accusation.
Accident investigations are the strict and sole purview of cold, analytical enquiry and emotions must never be brought into it.

megan

30th Oct 2015, 01:44

Perhaps Dave just got tired of the captions coming on and off and just said, "Screw it," and turned both transfer pumps off, intending to turn them back on before the supply tanks got "too" low. My guess is that when he finally did reach up to turn the transfer pumps back on he inadvertently got the "primes" instead. Hey, it's dark, and they're right next to each other. Who among us has never hit the wrong switch at night? My hand ain't up.The most succinct piece of reasoning on the thread explaining the possible "why". As you suggest, been done before. Aircraft ditched following a bolter on a carrier because the flaps were raised rather than the gear. Handles next to each other. Fuel low lights came on shortly after night take off. Fuel dump turned on rather than landing light off. Switches next to each other. Ergonomics.

DrinkGirls

30th Oct 2015, 10:20

A couple of points:

1. Its not a dick dance to manage the system. Even when extremely busy, you should be regularly scanning Ts+Ps. With this system, if you forget to switch the tx pumps back on, you get LOADS of information to remind you that you have forgot, AGES before it becomes a safety issue. (unless of course your supply tanks are showing permanent full).

2. Some are saying that they should look to see the history of landing fuel states. If they show regularly landing near to limits, something should be raised.
WHY???
Those limits are imposed by the authority to ensure a safe operation, a safety allowance is given in case of error or delay. If a unit regularly lands just above minimum fuel limits, they should be congratulated on being safe.
If the limits are not safe, the authority should change the limits. This is just like the military....... Boss says be there for 0800, SNCO says be there for 0750, JNCO says be there for 0745, erk gets there at 0740 'just to be sure'.

3. Despite people assuming that we are trying to say Dave wasn't at fault, I don't see anyone trying to excuse the ignoring of red fuel captions. The only thing that I am trying to say is that all may not be as black and white as we think. To EC135 operators, sit in the cockpit and imagine those supply tanks are nearing zero indicated. Not partially depleted, but actually NEARING ZERO. Even imagine that you are a serious risk taker....... Your TFO says "Dave, lets do one last quick important task before RTB". With 2 red lights and virtually empty supply tanks, I do not think that even Johnny Knoxville would seriously attempt that. So, despite him being at fault, SOMETHING caused/fooled/pushed him into continuing to fly............

Do I think Dave was at fault? Sadly, yes.
Do I think something distracted him? Almost certain of it
Do I know what? No, but the fuel gauges showing full are favourite
Should he have coped with that if it were true? Yes he should, but it didnt help
Would a CVR have helped? A no brainer, they should be in NOW

andyy

30th Oct 2015, 10:42

A CVR will help in the subsequent accident investigation, but how about trying to reduce the chances of that accident happening by designing aircraft that,

Dont have a "goofy" fuel system (to quote someone in a post above).

Dont have important switches next to each other so its easy to switch the wrong one off.

Dont give false senses of security from gauge readings.

As someone else has said, Its ergonomics, and it still seems to be sadly lacking.:ugh:

Humans make mistakes, dont do the logical or sensible things, push on when they shouldnt - but the chances of that happening will be reduced if the aircraft has been designed well in the first place, and CVR isnt a piece of good design, its an aid to finding out what was badly designed and what procedures were ignored in the first place.

Wageslave

30th Oct 2015, 10:44

A CVR would probably have told us nothing about this event except for timing of audio warnings.

We risk barking up the wrong tree here. Surely what really is needed is a FDR, not a voice recorder. Sure, while you're at it add the audio side, but it is systems data that would tell you the most in a silent single (non vocalised) pilot operation.

SilsoeSid

30th Oct 2015, 10:47

Well said Drinkgirls :D

SilsoeSid

30th Oct 2015, 10:56

My guess is that when he finally did reach up to turn the transfer pumps back on he inadvertently got the "primes" instead. Hey, it's dark, and they're right next to each other.

One would only say that if one didn''t know what would happen should the prime pumps be inadvertantly switched on.....

Video;

8_KvlaIYyIo

Perhaps there's a reason why the system is designed such that the cautions light up, the CAD bars flash and Master Caution illuminates when you put the prime pumps on.

[email protected]

30th Oct 2015, 14:54

A CVR would probably have told us nothing about this event except for timing of audio warnings. Except we would know what passed between the crew which could have been vitally important.

Presumably the FAI will include transcripts of the Airwave tasking and explain what would have been so important that an aircraft on fuel minimas had to be used.

MightyGem

30th Oct 2015, 18:27

I think a police pilot, at night with busy tasking and limited endurance, has quite enough to do without fannying around with fuel transfer pumps.
That's why I never used to turn them off if the captions were on due to the aircraft's attitude. I knew that I'd be changing the attitude shortly and the pumps would come back on.

[email protected]

30th Oct 2015, 18:45

Sounds an eminently sensible practice - was it SOP?

jellycopter

30th Oct 2015, 19:40

Why no autorotation?

There's a vast amount of comment about the fuel pumps and running out of fuel, but that's not ultimately what caused the crash.

The lack of a successful autorotation caused the crash. Had Dave auto'd safely down, we'd probably all be thinking that he was a 'good pair of hand for getting it down safely, but a bit of a ****** for running out of fuel'.

I find it extremely hard to imagine, that in the heightened sense of arousal after the first donk stopped, that he didn't do his damnedest to autorotate. Knowing his UK mil background and how engrained the reaction to low NR has to become, I'm very confident he was perfectly capable, albeit maybe out of practice for 'full downs'. We know from the report that the RRPM dropped below 97% and he managed to get it back once so he was clearly on his game, but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......

Reely340

30th Oct 2015, 20:15

jellycopter (http://www.pprune.org/members/34915-jellycopter) but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
Well, people in the know pointed to "Excessive lack of practize":
Thomas coupling (http://www.pprune.org/members/19161-thomas-coupling) This particular pilot hadn't done an EOL auto for possibly decades. See full post: http://www.pprune.org/rotorheads/569553-police-helicopter-crashes-onto-glasgow-pub-final-aaib-report-6.html#post9158989

Flugplatz

30th Oct 2015, 22:53

Ergonomics? He had plenty of hours to get familiar with all such 'Gotcha's'.

Too many opportunities for the pilot to intervene were not acted upon. Tired perhaps? or just been doing it for so many years that this one night he somehow just couldn't been bothered (oh look a light has come on... there's another one... whatever, I'm just so bored with this s**t).

I think that this incident, and the other recent 'mystery' accidents should prompt us at this stage to be thinking about an element of psychological review of the flightcrew in addition to the AAIB investigation. People go through a lot in life, at diifferent life stages, sometimes quite low for no obvious reaasons.

Flug

Wageslave

30th Oct 2015, 23:51

but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......

There can't be many possibilities. The only two I can think of are a visual miscue (height judgement) but to my mind that's unlikely as I can't see anyone setting up an auto into a dark built up city block. Why would you when the completely unobstructed river is right next to it?
The other, far more likely is simply panic. Seeing nowhere to go, not visualising the river as a clear area and an automatic motor response to arrest the descent occurring by reflex in what looked like a hopeless situation.
It's what people do, I'm afraid.

FH1100 Pilot

31st Oct 2015, 02:08

Sid, I get what you are saying. On a completely dark instrument panel, when you're looking directly at a screen focusing pretty much on the CAD display, then...yeah, those indications are pretty hard to miss. But the aircraft was VFR, over a city that was fairly well-lit. So there was probably plenty of light in that cockpit at the time. Not only that, but the evidence kind of shows that Dave was *not* looking at his instrument panel.

*IF* we believe that the EC-135's fuel quantity measuring and display system were functioning properly (and no concrete evidence was brought forth to suggest they were not), then how could Dave have *not* noticed his Supply tanks draining to zero? (What did he think was causing the low-fuel gongs?) Answer: He wasn't looking at the panel; his attention was directed somewhere else.

He cancelled the low-fuel gong multiple times. It is inconceivable to me that during that time he would not have looked at the gauges at least once! How is that possible? How do you misinterpret that graphic fuel quantity depiction?

Maybe...and like I said it's just a guess...but maybe when he reached up and turned the Transfers back on he wasn't even looking inside the cockpit (thus he didn't see the indications of Supply/Prime pump activation). We surely don't have any other plausible explanation why such a good pilot would make such an awful mistake. Maybe that's what bothers me the most about this crash.

And about Dave's auto? Like all of us, my ego makes me want to sit here and think to myself and promise you that *I* surely would have done a better job in that situation. But I cannot guarantee that. Perhaps I would have done the same thing, basically sitting frozen on the controls for those eight brief seconds. I like to believe I'm Chuck Yeager/Aaron/Norris all rolled into one awesome human bean. Most of the time though I'm just Chuckles the Clown. I cut that Dave guy a lot of slack.

handysnaks

31st Oct 2015, 02:47

And about Dave's auto? Like all of us, my ego makes me want to sit here and think to myself and promise you that *I* surely would have done a better job in that situation. But I cannot guarantee that. Perhaps I would have done the same thing, basically sitting frozen on the controls for those eight brief seconds. I like to believe I'm Chuck Yeager/Aaron/Norris all rolled into one awesome human bean. Most of the time though I'm just Chuckles the Clown. I cut that Dave guy a lot of slack.

Amen to that, brother!! :ok:

Special 25

31st Oct 2015, 08:10

There seems to be a surprising focus on the failure to make a successful auto following double engine failure. Perhaps this is due to the report which states that the reason for unsuccessful autorotation is unknown.

If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto.

You're low level
The first engine fails
You delay for a couple of seconds with shock, then carry out immediate actions
You're scanning the instruments and switches trying to work out why you have this confusion
You secure the engine
Suddenly the second engine goes
Multiple lights illuminate
The outside lights go dark
The NR has already dropped below safe
You have no option but to bottom the lever
Dropping through 300ft trying to recover Nr
Knowing you are descending way too fast and you have no accurate height figure
You know you have to raise the lever or certain crash

The difference between a Flaring too high, successful auto or crashing to the ground, probably about 2-3 seconds either way. Good luck perfecting that when you're also trying to look for somewhere safe to put the aircraft down and also trying to understand what has gone wrong.

The fact is the aircraft was upright and level when it hit the roof, just a few seconds after the second engine failure. Looking at the wreckage, it almost looked survivable and it possibly nearly was. A few seconds later before instigating the final 'pull', and it might have just had enough energy to arrest the descent into a heavy but survivable landing. Little point in debating this final element which the report acknowledges was in exceptionally demanding conditions.

As to the FDR/CVR. Its absence made no difference to this accident, just our understanding subsequently. As warnings are recorded by the onboard systems, this has yielded useful information. Just a shame that there isn't a time stamp on those captions as that would be an easy fix and would have provided more useful info.

Ergonomics, switch positions and 'what if' scenarios are being debated in the report and on this forum and within them is quite likely the answer to what went wrong. It probably doesn't matter which one of them is correct, as EC135 pilots are identifying possible scenarios that all need to be eliminated to help prevent similar accidents happening again.

SASless

31st Oct 2015, 09:04

Special,

Trying to write a Screen Play are you?

The Old Fat One

31st Oct 2015, 09:12

It seems odd to me that with so many chopper pilots now singing from the same page re this accident, that the AAIB put the AR failure down to "unknown". Have accident reports really become so anodyne that that there is zero tolerance to even educated speculation and, if so, are they not losing sight of the their real raison d'être? (to prevent re-occurrence, not that anybody should need to be told that)

Hyds Out

31st Oct 2015, 10:40

I have read through all the posts and I can't find any mention of when it is necessary to turn the Prime Pumps on. There are a lot of comments about the Transfer Pumps being off, and that the pilot inadvertently turned the prime pumps on when he meant to turn the transfer pumps back on.

Basically, with the fuel starvation, the engines would have started to suck air, and you get FUEL PRESS caution on CAD. The actions for this is to turn the PRIME PUMP(s) ON. This would explain the position of the switches, if that is how they were before impact.

Of course, not knowing what the fuel display actually indicated to him on the CAD, we will never know.

Another point raised by a colleague; once your electrical power is only being powered by the battery (following a double engine/generator failure), you constantly get a red BAT DISCH warning and audible gong appearing.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.

So put yourself in a position of looking out, at night, in auto over a city and you keep getting a red warning visible out of the corner of your eye, and the gong telling you (you assume) that the Nr is high (106%) and rising, so you raise the lever to contain (because that is what you are trained to do!! - forgetting in the heat of the moment that NR is your friend and it doesn't matter(to a point) if it gets too high) - where as the audio gong is for the BAT DISCH, and you cannot hear the Intermittent Low tone for LOW NR.

And it's proven that in high workload, it is your hearing that goes first. But as has been said, without a CVR/FDR....

biscuit74

31st Oct 2015, 11:45

FH1100. A very thoughtful post.

Your comments describe precisely what bothers me about this accident : I'm struggling to figure out what on earth can have been going on in that cockpit and more importantly in the mind of an experienced and evidently, in normal circumstances, entirely competent pilot, over quite a period of time.

As much as anything because of that sneaky horrible feeling ; if it can happen to someone like him, what chance have I got?

Hyds Out ; your description of the likely final sequence makes sense and also makes for dreadful reading/visualisation.

The human factors aspects are what intrigue and puzzle me.

SilsoeSid

31st Oct 2015, 12:11

I have read through all the posts and I can't find any mention of when it is necessary to turn the Prime Pumps on.

Probably because it was mentioned early on in the original thread.

Basically, with the fuel starvation, the engines would have started to suck air, and you get FUEL PRESS caution on CAD. The actions for this is to turn the PRIME PUMP(s) ON. This would explain the position of the switches, if that is how they were before impact.

Possibly, however imho the Eng Fail caution would trump the Fuel Press caution. Don't forget that even the Fuel caution cannot be confirmed as having been displayed, so any possible caution that should have illuminated may not have.

Another point raised by a colleague; once your electrical power is only being powered by the battery (following a double engine/generator failure), you constantly get a red BAT DISCH warning and audible gong appearing.
This is the same audio gong and another red warning in close proximity to the ROTOR RPM warning, which he probably also would have had in auto.

You'll continue to see the Bat Disch Warning, but the audible warning is cancelable.
The only Nr Warnings were for low Nr, which is a tone and not a gong.
The Batt Disch did not come on until the fourth Low Nr Warning was activated. (P.33)

Nr Low - <97% ---Steady light & intermittent low tone (800 Hz)
Nr High ->106% - Flashing light & warning gong
Nr High =>112% - Flashing light & continuous high tone (2400 Hz)

- forgetting in the heat of the moment that NR is your friend and it doesn't matter(to a point) if it gets too high) - where as the audio gong is for the BAT DISCH, and you cannot hear the Intermittent Low tone for LOW NR.

Forgetting you need Nr, really!!!
You can also hear the actually sound of the gearbox/Nr dropping Or rising itself.
Again, the Batt Disch did not come on until the fourth Low Nr Warning was activated. (P.33)

And it's proven that in high workload, it is your hearing that goes first. But as has been said, without a CVR/FDR....

I thought you just told us the sound of the gong was off putting to anything else that might have been going on :confused:

SilsoeSid

31st Oct 2015, 12:22

Hopefully the FAI will bring out any human factors issues that may have been present within the crew or unit as a whole, and ask any questions that the AAIB may not be able to.

SilsoeSid

31st Oct 2015, 12:56

Special25, I know what you are saying about sims, scenarios, situations and setups, but you paint a very different picture than that of the real situation;

"If I was putting someone through their paces in a simulator, would we fail one engine, and then while they were sorting out the first failure, give them a second failure at 600ft, low speed, at night, no landing light, over a city?? Of course not. You'd be setting them up to fail. It might be a demonstration of why not to get yourself into that position in the first place, but I can't imagine that many would turn that into a successful auto."

However, the real version of events, from page 7, is;

The helicopter tracked towards GCH at an altitude of about 1,000 ft amsl, with a ground speed of approximately 100 kt. Between 2221:35 hrs and 2221:45 hrs, when the helicopter was about 2.7 nm east of GCH, the right engine flamed out, leaving the pilot with one engine inoperative (OEI). Approximately 32 seconds later, about 1.8 nm east of GCH, the left engine flamed out.

Totally different situations.

jellycopter

31st Oct 2015, 13:10

Silsoe

you beat me to it

J

Hyds Out

31st Oct 2015, 13:35

Yes the ENG FAIL would trump the FUEL PRESS, but you still get FUEL PRESS first, hopefully.

With regards the warning for ROTOR RPM, the report says
"The next recorded warning was rotor rpm signifying an Nr of less than 97%".

Yes, the visual warning was recorded, but without an FDR, how it is not known that all of the 4 ROTOR RPM warnings related to low Nr. It doesn't stipulate exactly.

That was why I was highlighting the similarities between the high Nr gong at 106% and the BAT DISCH gong. Without a timescale for these warnings, they could have all merged into one. That is what I meant by the sound of the gong from the Battery may have affected other audio warnings.

My point about Nr control; is that when you are trained and tested in the real aircraft, you aim to keep 100-103% Nr, to prevent damage to the head/MGB. This gets ingrained, so that when you have something for real, you don't automatically let the Nr rise, because pilots rarely/ever train full done autos in the real thing in a MET helicopter.
This has been proven is some military helicopter accidents where the pilot only flew to the practice single engine Tq figures, as opposed to the real limits (pull the lever up to your armpit) because that's what they always did in training.

But overall, despite all the bells and whistles sounding, and looking at the table 3 on page 33 of the report, there were a few audio warnings, any pilot under a high workload with no spare capacity gets tunnel vision. That was my point about a person's hearing being the first thing to go. (Gongs vs Low tone vs gearbox noises vs cockpit noise). But again, things like that cannot be proven in a case like this.

You can see the difference in the evidence availability between this incident and the Norfolk 139.

Two's in

31st Oct 2015, 13:50

Have accident reports really become so anodyne that that there is zero tolerance to even educated speculation and, if so, are they not losing sight of the their real raison d'être? (to prevent re-occurrence, not that anybody should need to be told that)

There's more than enough information in the report to avoid another accident like this. All the speculation about what happened when it all went to rat**** is par for the course here, but a stopwatch set to RTB time would have avoided any need for superior skills.

sycamore

31st Oct 2015, 14:45

Flug, I think it was `Ergonomics` that killed the crew and others in this accident, and specifically `role` related,ie single pilot,night,V/IFR,police,SAR. Different from day V/IFR,VIP/pax.
As an ex-mil TP when assessing a particular cockpit for a particular `role`especially at night,one would spend hours working through scenarios/emergencies to determine the ideal postion of switches/lights/controls,and their shape /colour/feel/importance/relevance.
In the end ,one reached a compromise/best guess,as the manufacturer had already decided,unless one could change due to essential safety of flight considerations,supported by `higher authority`.
So,the first `gotcha` is the position of the fuel pump switches on the roof panel,not in line of sight,similar to other switches,not `beta lit`,and should be operated On/Off as required at low fuel states/low-speeds/attitude changes.Unsatisfactory,but people `worked around` the situation.
Not a problem for your VIP pilot,A-B,lightweight headset,no NVG, quick look-up,turn on switch,easy....
Second `gotcha` is the `Shed -Bus `switch,positioned at the rear /top of the panel....Not too difficult/dramatic if it` day VFR,but at night/IFR,if both genes.fail....and then a transmission/t-rotor,or double engine fail,do you have enough hands to get the lever down and fly the aircraft....?
Has there been any move to have a `shed-bus `switch in parallel ,mounted on the cyclic/collective,so that it is not necessary to go grovelling around the roof at this critical moment when you need lights and the rad.alt,as per the EASA requirements.....???? If not, why not...?
What happens when one has a double gene. failure? does the AFCS/A/P drop out; is the collective held by a `friction `knob or an electro clutch..can they be manually over-ridden..?do the hydraulics have accumulators for the control jacks..?
Why is the `Bat Disch` warning a `red` and a gong..surely it is only cautionary...

SilsoeSid

31st Oct 2015, 14:46

With regards the warning for ROTOR RPM, the report says
"The next recorded warning was rotor rpm signifying an Nr of less than 97%".

Yes, the visual warning was recorded, but without an FDR, how it is not known that all of the 4 ROTOR RPM warnings related to low Nr. It doesn't stipulate exactly.

I think it does if you read the rest of the paragraph, the same paragraph that says there were three Low Nr Warnings ... not your four;

"The next recorded warning was rotor rpm signifying an Nr of less than 97%. This warning cleared, returned, cleared again and then returned and remained active. The subsequent bat disch warning indicated that the battery was providing electrical power. The final warning was related to the autopilot."

"That was why I was highlighting the similarities between the high Nr gong at 106% and the BAT DISCH gong. Without a timescale for these warnings, they could have all merged into one. That is what I meant by the sound of the gong from the Battery may have affected other audio warnings.

If you look at Table 3, 'Warning Unit - warnings recorded in the NVM' on page 33, the time line clearly shows that the battery discharge gong didn't go off until after the third Low Nr Warning illuminated and remained on.

My point about Nr control; is that when you are trained and tested in the real aircraft, you aim to keep 100-103% Nr, to prevent damage to the head/MGB. This gets ingrained, so that when you have something for real, you don't automatically let the Nr rise, because pilots rarely/ever train full done autos in the real thing in a MET helicopter.

We train to settle the auto with the Nr between 97 and 106, ie the region outside of which you get an Nr warning. However please feel free to look up the power off Nr limitations :ok:

This has been proven is some military helicopter accidents where the pilot only flew to the practice single engine Tq figures, as opposed to the real limits (pull the lever up to your armpit) because that's what they always did in training.

Can we have some references please to these military double engine failures resulting in an autorotative landing please, or is that an opinion?
(Lever up to the armpit would surely only apply at the 'cushion on' stage at the end. We cant have the General spilling his G&T now, can we!

But overall, despite all the bells and whistles sounding, and looking at the table 3 on page 33 of the report, there were a few audio warnings, any pilot under a high workload with no spare capacity gets tunnel vision. That was my point about a person's hearing being the first thing to go. (Gongs vs Low tone vs gearbox noises vs cockpit noise).

Referring to Table 3;
Eight Audio Warnings were acknowledged, two of which were after both engines had stopped, so they must have been heard and acknowledged during this high workload, no engine, auto scenario at 100 kts, 1000'. The only audio warnings not acknowledged were the last three in direct succession; Low Nr, Batt Disch & AP ATrim ... right at the very ,very end.

You say nothing can be proven in a case like this, but at least have the respect for everyone involved to look at the facts as presented to you.

Hyds Out

31st Oct 2015, 16:03

Sorry I couldn't count. Having recounted, the table shows there were 5 audio and visual warnings relating to ROTOR RPM. But the point I was making is what data do they have to say those were in relation to high or low Nr?

Could one of the last BAT DISCH gongs at the end have been mis-interpreted as a high Nr gong, and therefore raising the lever to contain, when the Nr was already low? By this time there were a minimum of 4 red warning lights lit.

And regarding autos, as I said, AIM for 100-103%, which therefore keeps you nicely within the power off limitations.

And I have more than enough respect for those involved, but feel there are always learning opportunities, especially when audio warnings sound the same for different warnings. I am not picking holes in anyone else who had posted but hope the points I have raised invoke thought to the aircraft system beyond the fuel tank.

SilsoeSid

31st Oct 2015, 17:19

Sorry I couldn't count. Having recounted, the table shows there were 5 audio and visual warnings relating to ROTOR RPM. But the point I was making is what data do they have to say those were in relation to high or low Nr?

Actually the table shows that there were three audio and visual warnings relating to Low Nr.
I don't know what data the investigators had, but they reported that they were for the same reason, Low Nr;
"The next recorded warning was rotor rpm signifying an Nr of less than 97%. This warning cleared, returned, cleared again and then returned and remained active."

Could one of the last BAT DISCH gongs at the end have been mis-interpreted as a high Nr gong, and therefore raising the lever to contain, when the Nr was already low? By this time there were a minimum of 4 red warning lights lit.

Probably not as the Nr Warnings were for low Nr.
There was only one Batt Disch activation.
When the Bat Disch Warning came on there were only three Warnings showing, the two Low Fuels and the low Rotor Rpm.

And regarding autos, as I said, AIM for 100-103%, which therefore keeps you nicely within the power off limitatio

One minute you say there a very hard workload, the next you want someone to keep within a very tight rpm margin. A quick glance to look at the needle is probably the best you'll be getting from most.

And I have more than enough respect for those involved, but feel there are always learning opportunities, especially when audio warnings sound the same for different warnings. I am not picking holes in anyone else who had posted but hope the points I have raised invoke thought to the aircraft system beyond the fuel tank.

As with any incident, we are all going to learn and even change our practises and outlooks in large ways, every day is a learning day.
The Batt Disch Warning you continue to go on about to qualify your point was right at the very end of the timeline and only came on the once. Looking at the timeline this probably occurred within the last couple of seconds.

Of course I t is good to have different ways of looking at the same incident, however we should be very careful that we don't look at the published facts and shift them around to fit our version of events. When we have so many facts in front of us, opinion should start to take a back seat.

SilsoeSid

31st Oct 2015, 17:21

One thing that we may wish to consider here, is the effect of the lighting being on NVG mode.

chopjock

31st Oct 2015, 20:35

And regarding autos, as I said, AIM for 100-103%, which therefore keeps you nicely within the power off limitations.

All very well and dandy when practising. However, talking from first hand experience, (single engine only) when the donk quits unexpectedly, your eyes are outside looking for a place to land and the lever is all the way down whilst holding last attitude. Never once did I look at the gauges or pay attention to lights and gongs etc. not enough time to look back inside...

jayteeto

31st Oct 2015, 21:00

Maintain between 100 and 103% in a 135?

Good luck with that

MightyGem

1st Nov 2015, 10:30

Sounds an eminently sensible practice - was it SOP?
Not according to what others on here say that they do. In fact I didn't know that other people were turning the pumps off and on until after this accident.

I always read the FRC action as actions for a Transfer Pump failure, as it states in the FRCs. As I knew that the pumps hadn't failed, I didn't turn them off.

DrinkGirls

1st Nov 2015, 11:46

Problem is....... whilst you know it isn't a failure, you don't reallyknow, do you. If the caption has come on for the 10th time, THIS time might actually be a failure.

Distant Voice

1st Nov 2015, 12:18

First of all I feel that we are dealing with a "Mickey Mouse"fuel management system, with fuel slopping between supply tanks, and supply tanks and the main tank. On top of that we have to rely on a manual intervention to ensure that vital fuel transfer pumps are switched on, using unguarded switches.

I believe that the pilot and crew thought they were dealing with spurious"Low Fuel" lights; this belief is supported by a history of in-flight fuel content defects and subsequent No Fault Founds. In addition, prior to the illumination of a Low Fuel light there should have been an amber FUEL light. However, we read that in the case of an incident on 13th Dec 2013 that the fuel quantity in the supply tanks could be overestimated and that a "Low Fuel" light could appear without any "Fuel" caution being displayed before it. So, with quantity of fuel displayed appearing OK (but overestimated), and no Fuel light, it is only reasonable to assume that any "Low Fuel" light is likely to be spurious, given the history.

But why were the transfer switches OFF? Probable because the pilot received F PUMP FWD and F PUMP AFT warning captions when the contents in the main tank became low, lower that what it ended up with. At some point, due to manoeuvring, fuel from the supply tanks found its way back to the main tank (up to 35 Kgs was possible), and created an even distribution of fuel in the supply tanks. However, fuel going back into the main tank and covering the transfer pumps would not put the F PUMP FWD and F PUMP AFT warning captions on; so no warning. An even distribution of fuel in the supply tanks would account for the time between the two flame-outs being reduced from over 4 mins to just over 30secs. Design Failure

Bottom line is, I cannot believe that three people sat there and listen to alarms going off, watching fuel contents gauges for the supply tanks reducing to zero and did nothing about it, which includes informing ATC, and police on the ground. I also belief that one prime pump switch going from ON to OFF between first responders and the AAIB examination, is a clear indication that the "crime scene" was contaminated. Having said that, the notes do say that the prime pumps are switched on for engine start and certain emergency conditions. I am not sure which prime pump switch was affected, but if it relates to the first engine to flame out then it is possible that he was trying to do are-start, believing that he still had fuel in the supply tank.

Finally, Autorotation. The lack of RAD ALT and spot light must have been major contributing factors to the failure. The report and I think the pilot's notes, state that the power change over switch could be difficult to locate in an emergency. So why was it left like that? Why wait until someone tells you to have an automatic system? And how long does it take for the Rad Alt to run up and give accurate readings once the switch is found; probably a lot longer than the time taken to fall 300ft. DesignFailure.

DV