Police helicopter crashes onto Glasgow pub: final AAIB report

[8Pieced]

Not all Q's answered yet?

I wrote a post the other day but then my internet crashed and I lost it all, but the effort is worth it again as I believe I must express my views:


I'm one of the many who believe, GSPAO suffered a similar failure to GNWEM, an unknown failure to any 135 pilot at the time. Having NOT IGNORED but DISMISSED the low fuel warnings as they were contrary to an indication of full supply tanks, this then led to an extremely difficult Auto situation, again unknown to anyone at the time, that the pilot would only have 32 secs between Engine failures due to fuel starvation. I think the tasking and incorrect supply tank indication simply shifted the awareness of time and the longer they flew like this, the easier those red warnings slipped from their immediate attention, to the point of calmly conducting another task, as they were so convinced of a malfunctioning warning system.


The crew were probably very comfortable flying together and trusted each other's abilities, perhaps having done previous tasks in bad weather etc. I'm sure we would hear the pilot explaining that they should be seeing a fuel caution before the red warnings, and look my supply tanks are full, if there was a CVFDR fitted.


I've always flown the fuel I have in my tanks, if you fly on some tasks at 65kts you can gain another 10 minutes or so. Of course now I don't 100% trust my fuel readings as I'm aware of the GNWEM failure mode, and I suppose no one ever should fully trust their gauges now, an example of over reliance on modern technology. Does anyone know what time was the aircraft clock was indicating out of interest?


I believe the Turbomecca engines were more susceptible to the ingress of water/Ardrox contamination from cold washes - and I believe certain aircraft were more susceptible than others (having cold rinsed a specific 'T' for 3+ years, it was ok luckily for me), although Bond said it was random in the report. GSPAO seems to be very susceptible to this fuel sensor problem having read through its previous history, and it was cold washed only a few days prior to the accident - the perfect storm. With the subsequent chain of events, I fail to see any other explanation?


I'm sure that the pilot would have turned off his F PUMP FWD whilst at Dalkeith iaw procedures when it dry run, and am slightly disappointed that the AAIB or Manufacturer failed to show that this was possible - as right from the outset of the report, it then starts people wandering how the first pump was switched off, and how could he ignore pump cautions if he switched it off at any other time, etc which is complete nonsense. He has purposely turned off his Forward transfer pump, and the caution sits there in the middle of his CAD, all normal stuff, so to explain:


Simple, Strong NWl'y winds over the mountains, 25-30 kts at 2000- 5000 Feet, even the winds at 1200 AMSL are going to be quite different from the rather benign surface wind at Edinburgh of 300/8 kts. GSPAO is flying from 3000 AMSL ish to 1200', descending, decelerating (Nose up) and then doing some 'hovering there for 5-10 minutes', an actual max time of 5 mins in the end. The helicopter could quite easily have been drifting with the wind in a hover attitude (from the poor traces which I could see)or just at 5-10 kts IAS, but doing 30 kts ground speed! The AAIB tested 30 - 50 kts g/s based on their analysis and the manufacturer flew at 40 kts IAS?????? WHY? The FLIR arc was only 30 odd seconds of filming, extremely limited, what about the other 4-5 minutes including the descent from altitude? So we need to ask the question, what attitude would it need to be in order to dry run the pump for 3 minutes at roughly 200kgs? I believe, the F PUMP FWD caution was cancelled when dry running iaw normal procedure then simply forgot to be reset on leaving the hover, no reminders are there to do this and it is easily forgotten, remaining there in the middle becoming normality. I've done it before and will do again - unless AH kindly change their system.


The next pump would have been switched off in the transit of course as per normal procedure when dry running, so we are in the both pumps off situation. This is interesting as the flashing caution is cancelled by acknowledgment and the pilot would simply look up and switch the pump off - BUT NOT NECCESSARILY CHECK THE CAD AGAIN, SO NOW THERE ARE TWO PUMP CAUTIONS SITTING IN AN AREA WHERE WE COMMONLY ACCEPT (OR GET USE TO HAVING) ONE CAUTION AT LOWER FUEL STATES, AND NORMALLY ACCEPT TWO (GET USED TO HAVING TWO) WHEN LEFT WITH SUPPLY TANK FUEL ONLY!!. I once turned off both my pumps a few years ago, landed on, Police jumped out and I continued to do a ground run as some other bit of kit was playing up (distraction!), only to get my FUEL Caution appear - oops - I looked up and put both my transfer pumps straight back on! I wish I had MOR'd this in hindsight, you never know, if enough of us had done so, and I know there were others who must have done this, then EC/AH may have considered altering the design earlier. Lesson - let the authorities know of your experiences as they happen and then they can decide if you were just silly or whether the system needs changing. I don't believe the pilot on this night was protected with the benefit of a FUEL caution (due to my belief of a fuel sensor fault like GNWEM) - the immediate drill which would have been to check transfer pumps!


The checklists were only changed after the GWNEM incident and after the GSPAO accident, now stating that the pilot should believe the Fuel Warnings ahead of any other fuel indications as the Manufacturer was now aware of this new fault. The pilot of GSPAO did not have this specific warning and thus with some thought dismissed the LOW Fuel warnings as spurious. Checklists usually cover all spurious indication scenarios, ie a Caution showing but the gauge is ok etc. The GNWEM type of failure was not known about or pre-empted by anyone.


The report states that first responders photographed 1 prime switch off, so don't forget that please?! I don't believe this pilot would fly around with Prime Pump cautions. Both the prime switches were not on before the AAIB got there!! Both switches were subsequently found on, so this is a red hering? It could be conceivable that 1 of the primes was placed on if the fuel pressure reduced with the last bits of fuel being sucked up. So the pilot may have placed the prime pump on. My bet would be that the prime pump switched on was of the first engine to fail, no time to do this in auto for the second engine failure, let alone being able to find that shed bus switch in a dark cockpit, along with flying the aircraft!! So why can't we be told which switch in the first responder photograph was on, its not that difficult is it? If AAIB said one pump was off in the photo, which one?? But please don't start writing about scenarios with two prime switches on subsequently, if its rubbish anyway. Again it has the effect of making people believe that the cockpit panel was full of cautions and warnings, all ignored, but I don't believe it was, except of course the now super critical 2 Low Fuel Warnings which override everything......now.


Twin engine autos must not be overlooked, we don't do these enough, but have to successfully demonstrate them every 6 months to hover. A real autorotation, engine off in something like a single engine has probably become the equivalent training requirement of the FW pilot's lack of any real stall training. This was one highly experienced autorotation pilot, but may he not have had the opportunity apart from 1 or 2 in the last 6 months. All that said, it would still be an extremely difficult situation to successfully auto from in my opinion, even if I was warned prior to the event.


Lastly, when in auto, don't have a GONG for a Battery discharge which is the same GONG as when your NR rises through 106% Someone has previously talked about this but was slated by someone who I'd rather not fly with as he/she seems to know everything. The time shots for the warnings show a degree of NR control, NR ok, NR decayed to 97% but still within limits, NR OK, NR decayed to 97% but the snapshots do not have an elapsed time. It could be that the BATT discharge GONG and the Auto pilot GONG could be confused in this extremely critical time. In training a subconscious reaction to a warning GONG in autorotation is to pull in a heap of lever in order not to ground the heli at 112%. Please lets at least agree to change the sound of a GONG in an instance where it might be confused, don't just dismiss it. Something else which needs a further look at anyway.


The views above are purely mine. By all means please rip it apart as usual on here, but don't be satisfied that the experts always get things right. I think that there is some more flight testing to be done. I would also have been happier to see some kind of summary statement to the effect of 'It could have been possible that the particular pilot on that night was faced with a situation having never ever been considered as a failure mode by EC/AH, and thus would not have had the benefit of a FUEL Caution and so may have dismissed (not ignored) the Low Fuel Warnings. Checklists have now been rewritten to reflect this fault.......and reiterating that the autorotation would have been extremely demanding, the simple flying of which would probably have used up all remaining capacity, without the ability to activate a rather poorly placed Shed bus switch or even talk on a radio'.