Police helicopter crashes onto Glasgow pub
You suppose the AAIB has hung a 135 in such an attitude to confirm or deny fuel being able to flow back into the tanks?
Then again....what about the Transfer Pump Switches being in the OFF position.....why would that be?
Then again....what about the Transfer Pump Switches being in the OFF position.....why would that be?
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Sid - you are just making a tit of yourself.
For me this accident is but clarified.
1. Failure to manage transfer pumps leading to low fuel in both supply tanks. lets at least be crystal on this point - at his fuel state it is pure folly to continue to fly with neither pump switched on. He should have known this. Whatever the contents indications may or may not be, and there is evidence (Low Fuel Warnings) to suggest they were relatively accurate, basic airmanship should have ensured at least one pump was on. His selection of "PRIME PUMPS" on suggests poor system knowledge or at least cognitive failure during switch selection.
2. Failure to respond to warnings of LOW FUEL (recorded by the system computers) possibly due to overexposure in the past caused by poor systems knowledge and poor culture.
3. Failure to apply the Company MLA policy possibly due to distraction or more likely poor culture.
4. Failure to recognise the impending dangers and therefore failure to prepare, respond to and execute a successful EOL.
The evidence found thus far supports the above. I do not want to blame the pilot as accidents like this are usually associated with cultural or systemic failures leading inevitably to the incident or accident.
However, your failure to face the few important facts and available evidence is allowing you and others to utterly distort the issue which in itself perpetuates the obvious existing confusion amongst some of the EC135 pilots posting here and does a disservice to those EC135 pilots who know and manage their aircraft well.
For me this accident is but clarified.
1. Failure to manage transfer pumps leading to low fuel in both supply tanks. lets at least be crystal on this point - at his fuel state it is pure folly to continue to fly with neither pump switched on. He should have known this. Whatever the contents indications may or may not be, and there is evidence (Low Fuel Warnings) to suggest they were relatively accurate, basic airmanship should have ensured at least one pump was on. His selection of "PRIME PUMPS" on suggests poor system knowledge or at least cognitive failure during switch selection.
2. Failure to respond to warnings of LOW FUEL (recorded by the system computers) possibly due to overexposure in the past caused by poor systems knowledge and poor culture.
3. Failure to apply the Company MLA policy possibly due to distraction or more likely poor culture.
4. Failure to recognise the impending dangers and therefore failure to prepare, respond to and execute a successful EOL.
The evidence found thus far supports the above. I do not want to blame the pilot as accidents like this are usually associated with cultural or systemic failures leading inevitably to the incident or accident.
However, your failure to face the few important facts and available evidence is allowing you and others to utterly distort the issue which in itself perpetuates the obvious existing confusion amongst some of the EC135 pilots posting here and does a disservice to those EC135 pilots who know and manage their aircraft well.
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DB;
Distorting the issue! perpetuating confusion! By merely suggesting that the crashed ac's attitude was quite vertical! How's that then?
I would say it was you making the tit of yourself, mainly by jumping on Sasless's bandwagon!
Sid - you are just making a tit of yourself.
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However, your failure to face the few important facts and available evidence is allowing you and others to utterly distort the issue which in itself perpetuates the obvious existing confusion amongst some of the EC135 pilots posting here and does a disservice to those EC135 pilots who know and manage their aircraft well.
.
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However, your failure to face the few important facts and available evidence is allowing you and others to utterly distort the issue which in itself perpetuates the obvious existing confusion amongst some of the EC135 pilots posting here and does a disservice to those EC135 pilots who know and manage their aircraft well.
I would say it was you making the tit of yourself, mainly by jumping on Sasless's bandwagon!
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The helicopter’s fuel tank group was drained and the contents were measured immediately after it was extracted from the building. It was found that the main fuel tank contained 76 kg of fuel, whilst the No 1 supply tank (left) contained 0.4 kg of fuel and the No 2 supply tank (right) was empty. It has also been confirmed, by examination and measurement of the internal design features, that this was the fuel disposition at the time of the accident. That is; fuel had not moved within the tank group whilst the helicopter was at rest in the building. Also, there was no evidence that fuel leaked from the helicopter before or during the impact with the building.
The No 1 (left) engine fuel filter was found to contain a small amount of fuel whilst the No 2 (right) engine was found to be empty of fuel.
I'd suggest that whether or not such reasons exist, the big lessons are probably already on the table, namely:
1. The fuel system design of this aircraft is flawed.
2. Type rating training and OPCs do not adequately prepare all pilots for real engine failures.
Even if additional technical reasons existed and are found or speculated about, those two key issues will have to be dealt with.2. Type rating training and OPCs do not adequately prepare all pilots for real engine failures.
The first is easy to deal with, but please, no defenders of the existing system. There are other designs out there where the accident configuration simply COULD NOT have happened.
The second is IMHO a BIG issue that will take some courage and resources to confront.
If back drainage did in fact occur, flame out might not have been the cause and the low fuel warnings possibly only came on (no time stamp remember) post crash, as the levels decreased.
First LOW FUEL for each engine, afterwards LOW RRPM. That would rule out you above mentioned theory.
skadi
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Yep, good point skadi 
"The Warning Unit has provided information on the order in which warnings were triggered during the flight but not when they occurred. The unit recorded the normal warnings associated with starting the helicopter, followed by a warning free status. It subsequently recorded intermittent LOW FUEL 1 warnings for the left fuel supply tank, then a permanent LOW FUEL 2 warning for the right fuel supply tank. This was followed by a further temporary LOW FUEL 1 warning, before it became permanent for the remainder of the flight.
An alarm gong was also recorded followed by intermittent warnings relating to low rotor rpm. The penultimate warning recorded related to the battery discharging, which occurs when there is insufficient engine-driven generator power. The last warning related to an autopilot system failure."
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"The Warning Unit has provided information on the order in which warnings were triggered during the flight but not when they occurred. The unit recorded the normal warnings associated with starting the helicopter, followed by a warning free status. It subsequently recorded intermittent LOW FUEL 1 warnings for the left fuel supply tank, then a permanent LOW FUEL 2 warning for the right fuel supply tank. This was followed by a further temporary LOW FUEL 1 warning, before it became permanent for the remainder of the flight.
An alarm gong was also recorded followed by intermittent warnings relating to low rotor rpm. The penultimate warning recorded related to the battery discharging, which occurs when there is insufficient engine-driven generator power. The last warning related to an autopilot system failure."
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Last edited by SilsoeSid; 10th Mar 2014 at 10:13. Reason: Wanted to show my 'milk container' 135 fuel system model, but not worth the hassle!
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I think puntosaurus's quotes from the AAIB are key here. The tanks weren't damaged, and the wreckage was nose down. The front bottom of the supply tanks are closed, and so what was found in there should have been there on impact, give or take a tiny bit of splashing through the overspill holes.
If the aircraft had come to rest tail down, then it might have been ambiguous, as some of that 76kg of fuel could perhaps then have made its way through the overspill holes from the main tank into the supply tanks. The investigators have a lucky break that it didn't.
If the aircraft had come to rest tail down, then it might have been ambiguous, as some of that 76kg of fuel could perhaps then have made its way through the overspill holes from the main tank into the supply tanks. The investigators have a lucky break that it didn't.
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pitts-x (#2670) - The first point is correct, and so is the second . . . IF YOU FOLLOW THE FLIGHT MANUAL. Transfer of fuel from main to supply tanks, after having turned on the transfer pumps in the normal start sequence, IS automatic. The only changes come when fuel gets to a stage where one pump runs dry - as has been discussed in great detail - and that requires pilots to understand how the system works, and not deviate from the flight manual, just as in any other aircraft.
D-B (#2705) - I'm afraid you've hit the nail on the head, IMHO. If you are flying with both transfer pumps off and absolutely no fuel in the main tank, certainly UK Police by night, you should already be approaching to land - not 2 miles away, but descending & slowing with the helipad in sight, FULL STOP. Any pilot continuing to fly with both pumps off is putting their machine in a significantly risker profile than necessary, since they're not giving themselves the best chance to put any spilt/splashed/errant/attitude-corrected fuel into the safest place - i.e. the supply tanks!
punto - in the light of the above, I would refute your suggestion that the 135 fuel system design is flawed, as it has been working perfectly well for millions of hours and for many hundreds of pilots who've been flying this aircraft, (i.a.w. the Flight Manual) for 15 years or so.
D-B (#2705) - I'm afraid you've hit the nail on the head, IMHO. If you are flying with both transfer pumps off and absolutely no fuel in the main tank, certainly UK Police by night, you should already be approaching to land - not 2 miles away, but descending & slowing with the helipad in sight, FULL STOP. Any pilot continuing to fly with both pumps off is putting their machine in a significantly risker profile than necessary, since they're not giving themselves the best chance to put any spilt/splashed/errant/attitude-corrected fuel into the safest place - i.e. the supply tanks!
punto - in the light of the above, I would refute your suggestion that the 135 fuel system design is flawed, as it has been working perfectly well for millions of hours and for many hundreds of pilots who've been flying this aircraft, (i.a.w. the Flight Manual) for 15 years or so.
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Puntosaurus I completely disagree that the fuel system is flawed. It is designed to ensure a steady head of fuel to the engines when there are significant attitude changes but like all fuel systems it needs managing when the fuel states are low.
The type has flown 2.8 million hours without problems hitherto.
No aircraft will survive if critical fuel pumps are selected OFF at the point when they are most needed. The lesson here is that the fuel system requires knowledge and management but above all MLAs are in place for a reason. They mitigate the natural risks associated with very low fuel states.
SID you still won't face the facts.
The type has flown 2.8 million hours without problems hitherto.
No aircraft will survive if critical fuel pumps are selected OFF at the point when they are most needed. The lesson here is that the fuel system requires knowledge and management but above all MLAs are in place for a reason. They mitigate the natural risks associated with very low fuel states.
SID you still won't face the facts.
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If you are flying with both transfer pumps off and absolutely no fuel in the main tank, certainly UK Police by night, you should already be approaching to land - not 2 miles away, but descending & slowing with the helipad in sight, FULL STOP.
The frf for the SPAO was 85 kgs and for NPAS ac the frf is 105 kgs.
At the point at which the main tank indicates zero, SPAO would normally have just over a minute left to be on the ground. Suffice to say that NPAS ac should not be in the air at night with the main tank empty.
I have to agree that the system isn't flawed and is not difficult to manage.
SID you still won't face the facts.
Transfer pumps off, prime pumps on, supply tanks empty, main tank 76kgs, fault with CAD, warnings came on in 'expected' sequence for circumstances. No distress/urgency call, so far no indication that the crew knew of any problem.
Aircraft perfectly serviceable prior to incident, transmission stationary on impact. Nothing found in autopsy.
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Fuel drainage
No matter what the final attitude of the aircraft is, not all of the fuel would be able to drain from the supply tanks to the main- and there would always be some significant residual fuel left if the aircraft was at its observed final angle. The overflow holes are at the top of the tank. This is probably one of the reasons the AAIB have stated they are confident that the empty supply tanks and 76kg in the main is the fuel state of the aircraft at the time of the accident.
For tank 2 to be empty (and the corresponding fuel filter to be empty) then this supply tank must have run dry, and this correlates with the XFER pump being off.
For tank 2 to be empty (and the corresponding fuel filter to be empty) then this supply tank must have run dry, and this correlates with the XFER pump being off.
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Agreed, WorkingSection.
If it was upside down, nose down, then almost all of any fuel in the supply tanks could have drained out into the main tank, but that's not what happened.
If it was upright, but steeply tail down, then a lot of the main tank contents could have made it into the supply tanks.
In particular, if is was inclined, and tail down, then the lower supply tank could have filled substantially.
Either one of those scenarios would, I think, have substantially complicated the job for the investigators.
The information that the AAIB have and reported about the fuel levels in the tanks could easily have been compromised if the wreckage had come to rest in a different orientation.
If it was upside down, nose down, then almost all of any fuel in the supply tanks could have drained out into the main tank, but that's not what happened.
If it was upright, but steeply tail down, then a lot of the main tank contents could have made it into the supply tanks.
In particular, if is was inclined, and tail down, then the lower supply tank could have filled substantially.
Either one of those scenarios would, I think, have substantially complicated the job for the investigators.
The information that the AAIB have and reported about the fuel levels in the tanks could easily have been compromised if the wreckage had come to rest in a different orientation.
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DB
The AW109E power fuel system needs no attention when the fuel states are low, and will run down to unusable without any intervention if required.
I'm not trying to make a point about superiority of one manufacturer's system over another's. In fact there is a cheeky gotcha if you get a pump failure in the AW109E when the fuel state is low.
I'm just saying that it doesn't have to be the EC135 way. Even if you stick with the geometry of the 135 system, you could (as one poster has already suggested) have an 'auto' setting where the pump switches itself off when it runs dry, and re-engages when it is once again immersed in fuel. Or better still, you could simply design the pump to not care if it's running dry.
Puntosaurus I completely disagree that the fuel system is flawed. It is designed to ensure a steady head of fuel to the engines when there are significant attitude changes but like all fuel systems it needs managing when the fuel states are low.
I'm not trying to make a point about superiority of one manufacturer's system over another's. In fact there is a cheeky gotcha if you get a pump failure in the AW109E when the fuel state is low.
I'm just saying that it doesn't have to be the EC135 way. Even if you stick with the geometry of the 135 system, you could (as one poster has already suggested) have an 'auto' setting where the pump switches itself off when it runs dry, and re-engages when it is once again immersed in fuel. Or better still, you could simply design the pump to not care if it's running dry.
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So Punto - you agree it's not flawed. Just needs managing properly. I appreciate that its not easy for us to accept when we are wrong.
I am sure you are also aware that we have had two Police fuel starvations. this one and one in an A109!
Just stick to the few facts and common sense and leave the SWAGS to the rest.
I am sure you are also aware that we have had two Police fuel starvations. this one and one in an A109!
Just stick to the few facts and common sense and leave the SWAGS to the rest.
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It would be helpful to understand why the design is like it is from an engineering viewpoint but without that information, why do you think it is flawed?
Agreed it seems a little clumsy and there may be a good reason for not having an additional automatic mode, we just don't know.
Fuel management, in whatever form from endurance planning to quality to refueling safety to economic and accounting aspects ETC, is so utterly fundamental to being a pilot (glider pilots may disagree of course) you can't see the procedure for the 135 being too much of a challenge.
Exactly what do you think is wrong with it?
Agreed it seems a little clumsy and there may be a good reason for not having an additional automatic mode, we just don't know.
Fuel management, in whatever form from endurance planning to quality to refueling safety to economic and accounting aspects ETC, is so utterly fundamental to being a pilot (glider pilots may disagree of course) you can't see the procedure for the 135 being too much of a challenge.
Exactly what do you think is wrong with it?
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DB
The AW109E power fuel system needs no attention when the fuel states are low, and will run down to unusable without any intervention if required.
I'm not trying to make a point about superiority of one manufacturer's system over another's. In fact there is a cheeky gotcha if you get a pump failure in the AW109E when the fuel state is low.
The AW109E power fuel system needs no attention when the fuel states are low, and will run down to unusable without any intervention if required.
I'm not trying to make a point about superiority of one manufacturer's system over another's. In fact there is a cheeky gotcha if you get a pump failure in the AW109E when the fuel state is low.
http://www.aaib.gov.uk/cms_resources...pdf_508162.pdf
"The aircraft was returning from Morriston Hospital, Swansea to the operators base near Carmarthen with a pilot and two passengers onboard when it suffered a double engine failure due to fuel starvation at height of approximately 400 feet above ground level (agl)."
"there's a cheecky gotcha" yup wherever there's a "cheecky gotcha" it'll get someone sometime, just a mater of time. The Law according to Murphy.
Can't just blame the pilot, even if it was 'his error'
This is more (double) engine failures than the (flawed) theory promoting twin engined helicopters predicts. THEREFORE the theory is WRONG. (then add in all the extra risks from daft gearboxes etc )
1 in how many billion? Yea yea
The Fuel System design harkens back to certification requirements and the ability to dump fuel....as I recall it being told by a Factory Pilot doing 105/117 Training....with the 135/145 being follow-on designs.
We had major concerns over the Fuel System design when working up an IFR EMS Program for Duluth, Minnesota back in the late 80's...early 90's.
In theory it is a fine system....but does have some quirks that can bite you in the Butt if abnormal situations crop up at the wrong time and place. Putting the Pump Switches up on t he Overhead Panel seems to be a step backwards re safety in my view....they would have been better to leave them on the center console where you can see the things in the Dark and while wearing NVG's.
We had major concerns over the Fuel System design when working up an IFR EMS Program for Duluth, Minnesota back in the late 80's...early 90's.
In theory it is a fine system....but does have some quirks that can bite you in the Butt if abnormal situations crop up at the wrong time and place. Putting the Pump Switches up on t he Overhead Panel seems to be a step backwards re safety in my view....they would have been better to leave them on the center console where you can see the things in the Dark and while wearing NVG's.
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The thing about human factors is clever people do stupid things. I suggested at the beginning of this thread, in a roundabout way, the pilot had turned the fuel off. It happens. Whether the system is "flawed" or not, it's self-evidently possible to make a mistake.
My understanding is the pumps can run dry for 30 minutes. If that is true, I would turn both on at the beginning of a flight and not touch them again. By my reckoning, when a pump would run dry for 30 minutes you don't have 30 minutes fuel left.
If you think yourself you're too smart to make a simple error you don't understand the problem.
My understanding is the pumps can run dry for 30 minutes. If that is true, I would turn both on at the beginning of a flight and not touch them again. By my reckoning, when a pump would run dry for 30 minutes you don't have 30 minutes fuel left.
If you think yourself you're too smart to make a simple error you don't understand the problem.