Police helicopter crashes onto Glasgow pub: final AAIB report
I never saw a dump valve installed as it doesn’t make much sense at the heights helicopters fly and the small amounts of fuel we carry.
No toggling them depending on whether one does a prolonged hover or goes 120kts. Apparently the BO105 pumps have no issues running dry.
Hence I for one would never have approved certification of an a/c whose fuel system mangement is more hassel the its predecessor's.
But then again I, too, would have dismissed a fuel level sensing system that is the opposite of fail save:
e.g. one that indicates way more fuel in the tank than there actually is as soon as a droplet(!) of water gets in between the two concentric fuel sensor tubes.
Mind you it's ok if it is affected by water ingress but it is paramount that it were fail SAFE, meaning in that case it may only indicate LESS fuel that there actually is.
So with 1) a decent fuel supply system and 2) a fail safe fuel sensor system that accident simply wouldn't have happened.
Capable pumps simply stay on till engine shutdown at home.
Fail safe fuel indicators wouldn't have created a laid back attitude toward various fuel warning lights illuminating, where recurrent acknowledgement of them might become standard behavior.
It might be hard to memorize which fuel warning light really means business when lit and which might just indicate a recently hot pressure washed turbine.
Then again I guess I might be way to critical (and/or uninformed) to work in an certification environment.
Here a quote from some BO105 FM Pg. 3 - 14
WARNING LIGHT INDICATIONS LOW FUEL
Conditions/Indications Failure of both main tank pumps, or Main tank empty
– Supply tank fuel quantity below 60 kg (75 l)
Procedure
1. Supply tank fuel level – Check
2. Main tank fuel level – Check
3. Both fuel main pump circuit breakers – Check in
4. Both fuel main pump switches – Check on
If LOW FUEL warning light remains on:
5. LAND WITHIN 10 MINUTES
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The Bo105 certainly did have a fuel dump capability. It was the only way it could get a practical Group A Certification. Engine fails dump fuel and restore OEI performance to something passable ie. you stopped going down.
In 1990 MBB issued a service letter explaining that a review of the certification data had shown an overestimation of performance by 175kg and all graphs relating to performance should be altered accordingly. The following week MBB issued another service letter explaining that due to an improvement in the main gearbox life 175 kg can be added to all graphs with immediate effect provided the MGB was lubricated by (here it gave the spec no. for an Esso oil that I can no longer remember. Read into this what you will but I cannot imagine that the 175 kg performance 'error' truly represented the otherwise meticulous German precision in all things technical. Methinks there was touch of the Neslon's eye about that particular nonsense.
We also had fuel dump fitted to our (BCAL (H) ) Sikorsky S61Ns for the same reasons - we needed to have Group A performance when we crossed the coast outbound but could operate Group B until then. It gave us enough extra fuel to make a difference.
G.
In 1990 MBB issued a service letter explaining that a review of the certification data had shown an overestimation of performance by 175kg and all graphs relating to performance should be altered accordingly. The following week MBB issued another service letter explaining that due to an improvement in the main gearbox life 175 kg can be added to all graphs with immediate effect provided the MGB was lubricated by (here it gave the spec no. for an Esso oil that I can no longer remember. Read into this what you will but I cannot imagine that the 175 kg performance 'error' truly represented the otherwise meticulous German precision in all things technical. Methinks there was touch of the Neslon's eye about that particular nonsense.
We also had fuel dump fitted to our (BCAL (H) ) Sikorsky S61Ns for the same reasons - we needed to have Group A performance when we crossed the coast outbound but could operate Group B until then. It gave us enough extra fuel to make a difference.
G.
Last edited by Geoffersincornwall; 7th Nov 2018 at 22:20. Reason: corrected the 15 to 175 - typing error
and if I ˋm not totally mistaken, the Sea Lynx had also (25 years ago)
I was specifically referring to Part 29 Civilian Certified Helicopters.
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In the H135 the transfer pump and prime pump switches are now of different design, so by feel you know which are which. Once on, you leave the transfer pumps on even if the main tank runs dry, or a pump runs dry due to hover work with lower fuel, IMO a simple system and just two switches to put on along with other switches for other functions as part of the startup checklist.
Tucumseh;
There was a change to the checklist to make it clearer and the CAA mandated a higher minimum landing fuel (90kg rather than 60).
We loaned a 135 to the AAIB for some tests and also flew the CAA. There was a test of the systems fleet wide and the aircraft carried on.
SND
There was a change to the checklist to make it clearer and the CAA mandated a higher minimum landing fuel (90kg rather than 60).
We loaned a 135 to the AAIB for some tests and also flew the CAA. There was a test of the systems fleet wide and the aircraft carried on.
SND
In the H135 the transfer pump and prime pump switches are now of different design, so by feel you know which are which. Once on, you leave the transfer pumps on even if the main tank runs dry, or a pump runs dry due to hover work with lower fuel, IMO a simple system and just two switches to put on along with other switches for other functions as part of the startup checklist.
Since when is this the case? A buddy of mine flying HEMS in an EC135 confirmed that the AFM demanded pump toggling when the active one is running dry due to fuselage attitude. That was a couple of years ago.
IIRC the EC135 has pump temp sensors that would activate a pump-xyz light suggesting to switch off the associated pump until it will be reemerged in fuel or something.
The switches and the alert logic have changed in the EC135.
The switch change (dual action) became standard from s/n 2027 so will be build standard on all new P3H and T3H. It is also available as SB (SB EC135H-28-001).
The logic to illuminate the AFT and FWD FUEL PUMP has changed on P3H and T3H. The alert no longer illuminates for dry running pumps so no drill to switch them off. The amber caution is replaced with a white advisory MAIN FUEL LOW to bring to the crews attention that fuel is running low.
The pump alert is not driven driven by a temperature sensor. It is driven by a shunt that senses the current and triggers the alert.
The switch change (dual action) became standard from s/n 2027 so will be build standard on all new P3H and T3H. It is also available as SB (SB EC135H-28-001).
The logic to illuminate the AFT and FWD FUEL PUMP has changed on P3H and T3H. The alert no longer illuminates for dry running pumps so no drill to switch them off. The amber caution is replaced with a white advisory MAIN FUEL LOW to bring to the crews attention that fuel is running low.
The pump alert is not driven driven by a temperature sensor. It is driven by a shunt that senses the current and triggers the alert.
As someone who was deeply involved in the Policing side of Police Air Operations during the whole of the 1990's and then after as a Liaison officer employed by the then Eurocopter as an interface with Police units, so my familiarity with Police Air operations remained up to date. In addition I visited all units including the one being used by this particular aircraft. All of the Police Air Observers constantly impressed me by their professionalism and knowledge of the finer points of their specialism's. The same admiration was levelled at the Pilots who operated in my opinion to the very highest standard commensurate with their role. Indeed once into the job they became just as enthusiastic thief catchers as the Police crew.
It is for that reason, and in the full Knowledge that all Police radio transmissions are recorded at Force Control Rooms, I have never understood why the last 15 minutes or so of Police radio conversations never appeared to feature in that investigation.
The aircraft had been on a long deployment and was returning to base at the maximum of its endurance. The Police officers on board were experienced and would have not missed the warning light that fuel was low. At some point whilst making its direct route into its base the A/C appears to have diverted to be over the Pub. Why? What caused it to do that? From my own experience all of those factors would have been communicated to Force control?
Were those tapes examined? If they were and contained nothing of significance then say so. But I will never accept that the crew knew nothing of the low fuel situation they were in.
TF
It is for that reason, and in the full Knowledge that all Police radio transmissions are recorded at Force Control Rooms, I have never understood why the last 15 minutes or so of Police radio conversations never appeared to feature in that investigation.
The aircraft had been on a long deployment and was returning to base at the maximum of its endurance. The Police officers on board were experienced and would have not missed the warning light that fuel was low. At some point whilst making its direct route into its base the A/C appears to have diverted to be over the Pub. Why? What caused it to do that? From my own experience all of those factors would have been communicated to Force control?
Were those tapes examined? If they were and contained nothing of significance then say so. But I will never accept that the crew knew nothing of the low fuel situation they were in.
TF
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Really?
How about when my gauges read 47/26/43 and both the red lights came on pretty close to each other. There was just over 40kg total on board.
How about when my gauges read 47/26/43 and both the red lights came on pretty close to each other. There was just over 40kg total on board.
Why are we going round the houses again?
We (police pilots) know what happened:
He went for one final recce enroute RTB.
He was virtually visual with home when he carried out a quick hover, thinking he could 'shave' a couple of minutes off the night fuel reserve because he was so close. The Tx pumps were off (had been for ages). No lights were showing.
One engine starved of fuel.
He did what he did to manage the situation whilst in the hover over town, at night. During this 'management process' the other donk stopped.
He lost control of Nr.
A/c fell out of the sky.
Correct me if this has, in any way, diverged from the original assumptions over the years?
We (police pilots) know what happened:
He went for one final recce enroute RTB.
He was virtually visual with home when he carried out a quick hover, thinking he could 'shave' a couple of minutes off the night fuel reserve because he was so close. The Tx pumps were off (had been for ages). No lights were showing.
One engine starved of fuel.
He did what he did to manage the situation whilst in the hover over town, at night. During this 'management process' the other donk stopped.
He lost control of Nr.
A/c fell out of the sky.
Correct me if this has, in any way, diverged from the original assumptions over the years?
Tightgit
We (police pilots) know what happened:
We might make an educated guess.
Our guess may prove to be correct.
But we don't know!
But why that final Recce on route back to base? What Instructions had been given from Control? That is why I am asking why were Police C/R communications during that time not explored?
TF
TF