Police helicopter crashes onto Glasgow pub
Purveyor of Egg Liqueur to Lucifer
2 options here
1. The same as I would have done as soon as that first engine quit for no reason! (which happens to be the same as the most recent amendment ref warnings!)
2. Call up air traffic, ask them to post a thread on PPRuNe and wait for an answer!
1. The same as I would have done as soon as that first engine quit for no reason! (which happens to be the same as the most recent amendment ref warnings!)
2. Call up air traffic, ask them to post a thread on PPRuNe and wait for an answer!
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SilsoeSid
I have been having sleepless nights thinking about the fuel system on the 135.
It only takes one NRV valve to fail and fuel will be trapped in main tank.
Transfer pumps have to be manually turned on and off depending on attitude, why o why aren't they automated. The electronics are already in place to give warning, just have it turning the pumps on and off.
I modified the fuel system on my aircraft to a flop tube, it follows the fuel in any attitude.
I firmly believe design issues are at fault here.
I have been having sleepless nights thinking about the fuel system on the 135.
It only takes one NRV valve to fail and fuel will be trapped in main tank.
Transfer pumps have to be manually turned on and off depending on attitude, why o why aren't they automated. The electronics are already in place to give warning, just have it turning the pumps on and off.
I modified the fuel system on my aircraft to a flop tube, it follows the fuel in any attitude.
I firmly believe design issues are at fault here.
Purveyor of Egg Liqueur to Lucifer
So you are in the hover with 70 litres unusable in the main tank, transfer pumps off. Both supply tanks are full so you have about 20 mins flight time remaining.
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?
Besides, are you still going to 'happily' fly around after an engine has unexpectedly quit for no apparent reason?
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Silsoe
I did. A very good post it was too. One which perfectly illustrates the advantage of two pilots over one. If I were faced with the kind of situation described, which has the capacity to promote incorrect actions, I would much rather have a second professional alongside me with a vested interest in the preservation of (our) lives.
Much rather deal with serious malfunctions whilst not having to actually fly the thing, or refer to another pilot to confirm (or otherwise?) my suspicions. Normally (though admittedly not always) such decision making is more robust and considered when two people are involved.
Even more important when these 'situations' can occur at low level over city centres. Which is precisely why the two pilot suggestion entered these discussions in the first place.
Tr, perhaps the problem is understood more easily by reading Art of Flights earlier posts from around the 28th ….
Much rather deal with serious malfunctions whilst not having to actually fly the thing, or refer to another pilot to confirm (or otherwise?) my suspicions. Normally (though admittedly not always) such decision making is more robust and considered when two people are involved.
Even more important when these 'situations' can occur at low level over city centres. Which is precisely why the two pilot suggestion entered these discussions in the first place.
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Besides, are you still going to 'happily' fly around after an engine has unexpectedly quit for no apparent reason?
Transition to fwd flight above 80kts, forward transfer pump on and hope that 6 litres a minute flow will get your number two supply tank topped up in time
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Fotyodd2
Are you familiar with the Air Navigation Order?
Are you familiar with Rule 5, and the term Congested Area?
Are you aware that police aircraft enjoy some significant exemptions, from those rules governing other aircraft?
Need we continue?
It could be reasonable to suggest that such exemptions from 'safety related' rules should require the VERY highest safety standards whilst exercising those privileges, which have the capacity to impact (quite literally) on large numbers of innocent people!
Are you familiar with the Air Navigation Order?
Are you familiar with Rule 5, and the term Congested Area?
Are you aware that police aircraft enjoy some significant exemptions, from those rules governing other aircraft?
Need we continue?
It could be reasonable to suggest that such exemptions from 'safety related' rules should require the VERY highest safety standards whilst exercising those privileges, which have the capacity to impact (quite literally) on large numbers of innocent people!
Tandem,
1. Yes.
2. Yes and Yes.
3. Yes.
4. Well, actually yes because my question to you was "what do you consider to be "Low Level"? which you didn't answer.
I could also add "are you familiar with the NPAS Ops Manual"?
1. Yes.
2. Yes and Yes.
3. Yes.
4. Well, actually yes because my question to you was "what do you consider to be "Low Level"? which you didn't answer.
I could also add "are you familiar with the NPAS Ops Manual"?
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Fortyodd2
What I consider to be "Low Level", is precisely what the CAA considers to be "Low Level".
That would be a "Level" 'Lower' than most other aircraft are, for safety reasons, allowed to operate. A "Level" 'Low' enough to require special exemption. As distance from the ground (and other objects) decreases, so safety margins reduce, as the time available for an appropriate response is minimised. Particularly relevant when operating overhead large numbers of innocent people.
Perhaps you have some alternative definition?
Do please say if you believe the provisions of the NPAS Ops manual denies you any such exemptions?
Need we continue?
4. Well, actually yes because my question to you was "what do you consider to be "Low Level"? which you didn't answer.
That would be a "Level" 'Lower' than most other aircraft are, for safety reasons, allowed to operate. A "Level" 'Low' enough to require special exemption. As distance from the ground (and other objects) decreases, so safety margins reduce, as the time available for an appropriate response is minimised. Particularly relevant when operating overhead large numbers of innocent people.
Perhaps you have some alternative definition?
Do please say if you believe the provisions of the NPAS Ops manual denies you any such exemptions?
Last edited by Tandemrotor; 31st Dec 2013 at 14:24.
Purveyor of Egg Liqueur to Lucifer
Silsoe
Tr, perhaps the problem is understood more easily by reading Art of Flights earlier posts from around the 28th ….
Tr, perhaps the problem is understood more easily by reading Art of Flights earlier posts from around the 28th ….
Just to remind y'all, I'm still waiting for a reply to the questions;
Art, are you in the habit of cancelling the caution automatically and then diagnosing a problem without referring to the CAD?
Did it say ENG FAIL or FADEC FAIL ?
Apart from that 30 sec limit indication, did the VEMD indicate anything else, such as ENG FAIL ?
Were there any further indications of that diagnosed engine failure, such as the CAD also indicating ENG OIL P and GEN DISCON ?
Did it say ENG FAIL or FADEC FAIL ?
Apart from that 30 sec limit indication, did the VEMD indicate anything else, such as ENG FAIL ?
Were there any further indications of that diagnosed engine failure, such as the CAD also indicating ENG OIL P and GEN DISCON ?
Another question for Art, what was the indication of zero torque that you saw?
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Sorry PieChaser, I'm a bit confused.
So, if I have this right, you're in the hover running on supply tanks, having switched off the transfer pumps because of the ac attitude and an engine fails. You transition to forward flight, switch back on the transfer pumps and get a number 2 amber low fuel light.
I would hamper a guess that everyone here apart from you will know what they would do next, it's just your cunning option 2 that isn't quite clear.
Well, if it's likely to be a problem, why isn't anything mentioned in the single engine failure part of the book? If you have any doubts, how about using the prime pump?
So you are in the hover with 70 litres unusable in the main tank, transfer pumps off. Both supply tanks are full so you have about 20 mins flight time remaining.
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?
So transition to forward flight, speed above 80 kts, Amber warning supply tank two, now what?
I have been having sleepless nights thinking about the fuel system on the 135.
It only takes one NRV valve to fail and fuel will be trapped in main tank.
Transfer pumps have to be manually turned on and off depending on attitude, why o why aren't they automated. The electronics are already in place to give warning, just have it turning the pumps on and off.
I modified the fuel system on my aircraft to a flop tube, it follows the fuel in any attitude.
I firmly believe design issues are at fault here.
It only takes one NRV valve to fail and fuel will be trapped in main tank.
Transfer pumps have to be manually turned on and off depending on attitude, why o why aren't they automated. The electronics are already in place to give warning, just have it turning the pumps on and off.
I modified the fuel system on my aircraft to a flop tube, it follows the fuel in any attitude.
I firmly believe design issues are at fault here.
Over a built up area at night with only a few minutes of useable fuel left, option two might be the only option!
Transition to fwd flight above 80kts, forward transfer pump on and hope that 6 litres a minute flow will get your number two supply tank topped up in time
Transition to fwd flight above 80kts, forward transfer pump on and hope that 6 litres a minute flow will get your number two supply tank topped up in time
I would hamper a guess that everyone here apart from you will know what they would do next, it's just your cunning option 2 that isn't quite clear.
and hope that 6 litres a minute flow will get your number two supply tank topped up in time
Pie,you must be more specific as to a `single NRV` Failure`,Does it fail `open or closed...?In either case selecting both transfer pumps on will still supply fuel to No 2 engine tank.Anyway why would anyone switch off the aft transfer pump in the hover; going by the diagram on p52 it should supply fuel continuously,as it `appears to be in the `centre` of the tank layout.
I would agree that it appears a `crap design`,with no low level flow connections with `flapper valves`.
I would agree that it appears a `crap design`,with no low level flow connections with `flapper valves`.
Hi Tandem,
Sorry for taking a while to reply - I've just been out "low flying" in accordance with my CAA approved Operations Manual which, you'll be delighted to know, does contain one or two exemptions to allow me, as aicraft captain, in certain defined circumstances, to operate at "lower levels" should the weather conditions, (read Cloudbase), prevent me from operating at the higher level I would prefer - but only when the need/task dictates. It does not exempt me from having to explain myself to the CAA should the need arise.
The Ops Manual is not a whole lot different from the PAOM which you will be familiar with, being an ex police pilot, but it does state that, wherever possible, routine transits shall be above 1500ft agl.
Sorry for taking a while to reply - I've just been out "low flying" in accordance with my CAA approved Operations Manual which, you'll be delighted to know, does contain one or two exemptions to allow me, as aicraft captain, in certain defined circumstances, to operate at "lower levels" should the weather conditions, (read Cloudbase), prevent me from operating at the higher level I would prefer - but only when the need/task dictates. It does not exempt me from having to explain myself to the CAA should the need arise.
The Ops Manual is not a whole lot different from the PAOM which you will be familiar with, being an ex police pilot, but it does state that, wherever possible, routine transits shall be above 1500ft agl.
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This was my original post:
There are two engine driven pumps, two prime pumps, two transfer pumps and two non return valves, but the way I see it if one of those valves sticks open on a switched off transfer pump (normal practice), then the other transfer pump will continue circulating fuel back into the main tank instead of the supply tanks. As the transfer pumps warning lights work on amps drawn, it would not illuminate!
Imagine the scenario. Pilot knows how much fuel should be remaining backed up by main tank fuel gauge. If as the AIB suggested there is 95 lt fuel remaining then in the cruise it is likely the rear transfer pump would run light and so be switched off. Forward pump would still be operating normally so no warnings there. But if the aft check valve is stuck open, that fuel is not getting to the supply tanks. Pilot gets low fuel warning but is puzzled because he knows there is fuel in there, he knows his transfer pump is working, does he believe that warning light? First engine flames out. Pilot has 2 or 3 mins to sort this out or land. If he can visualize his fuel system and tanks, he may just pull the nose up and get some fuel over the rear fence, turn on his rear transfer pump, anything to get some fuel in the supply tanks. Pumps cavitating, engine trying to re light.
All conjecture I know, but it's my best guess for a double engine flame out and stopped drive train. Also I do know they were doing extensive fuel system testing on a 135 next to our hangar on Friday!
There are two engine driven pumps, two prime pumps, two transfer pumps and two non return valves, but the way I see it if one of those valves sticks open on a switched off transfer pump (normal practice), then the other transfer pump will continue circulating fuel back into the main tank instead of the supply tanks. As the transfer pumps warning lights work on amps drawn, it would not illuminate!
Imagine the scenario. Pilot knows how much fuel should be remaining backed up by main tank fuel gauge. If as the AIB suggested there is 95 lt fuel remaining then in the cruise it is likely the rear transfer pump would run light and so be switched off. Forward pump would still be operating normally so no warnings there. But if the aft check valve is stuck open, that fuel is not getting to the supply tanks. Pilot gets low fuel warning but is puzzled because he knows there is fuel in there, he knows his transfer pump is working, does he believe that warning light? First engine flames out. Pilot has 2 or 3 mins to sort this out or land. If he can visualize his fuel system and tanks, he may just pull the nose up and get some fuel over the rear fence, turn on his rear transfer pump, anything to get some fuel in the supply tanks. Pumps cavitating, engine trying to re light.
All conjecture I know, but it's my best guess for a double engine flame out and stopped drive train. Also I do know they were doing extensive fuel system testing on a 135 next to our hangar on Friday!
PieChaser,
" As the transfer pumps warning lights work on amps drawn, it would not illuminate!" - actually, it would already be illuminated because you'd already stated it was switched off.
The Fuel Low sensors are not looking for a "quantity" of fuel, simply "am I immersed in fuel or not".
Regardless of what the gauge says, Red Low Fuel 1 or 2 with associated audio warning means, and I'm quoting from the FRC's here,
1. Fuel Qty indication - Check
If positive fuel indication in the main tank:
2. Both fuel pump XFER sw - Check ON
3. Both fuel pump XFER circuit breakers - Check in.
If FUEL LOW WARNING LIGHT remains on:
4. Air Conditioning - Switch Off
5. Bleed Air - Switch Off
6. LAND WITHIN 8 MINUTES
At no stage does it suggest that a pilot should "Question" the warning light.
The pilot does not have 2 or 3 minutes to sort this out or land - the pilot has 2 or 3 minutes to land.
" As the transfer pumps warning lights work on amps drawn, it would not illuminate!" - actually, it would already be illuminated because you'd already stated it was switched off.
The Fuel Low sensors are not looking for a "quantity" of fuel, simply "am I immersed in fuel or not".
Regardless of what the gauge says, Red Low Fuel 1 or 2 with associated audio warning means, and I'm quoting from the FRC's here,
1. Fuel Qty indication - Check
If positive fuel indication in the main tank:
2. Both fuel pump XFER sw - Check ON
3. Both fuel pump XFER circuit breakers - Check in.
If FUEL LOW WARNING LIGHT remains on:
4. Air Conditioning - Switch Off
5. Bleed Air - Switch Off
6. LAND WITHIN 8 MINUTES
At no stage does it suggest that a pilot should "Question" the warning light.
The pilot does not have 2 or 3 minutes to sort this out or land - the pilot has 2 or 3 minutes to land.
Avoid imitations
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Fortyodd2, are you saying the PAOM Pt2 that I once spent my entire Christmas break writing, unpaid, out of the goodness of my heart, is no more? What a tragedy! 
Shy,
Yep, it's gawn. It served us well and went from issue 2 to issue 4.2 during my authorship - I even went to the extremes of colour photos and double sided printing - but it was one of the first things in the bin on 2nd October. Managed to save an electronic copy for posterity but can't bring it anywhere near work. Not a total loss though as one or two of my better efforts are now in the NPAS Ops Manual.
Yep, it's gawn. It served us well and went from issue 2 to issue 4.2 during my authorship - I even went to the extremes of colour photos and double sided printing - but it was one of the first things in the bin on 2nd October. Managed to save an electronic copy for posterity but can't bring it anywhere near work. Not a total loss though as one or two of my better efforts are now in the NPAS Ops Manual.
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My time in police flying significantly preceded the writing and introduction of the PAOM. Though I was of course around when it came in.
Prior to that, police flying was just a private operation. Akin to a PPL owning a C150, albeit with those all important exemptions!
Prior to that, police flying was just a private operation. Akin to a PPL owning a C150, albeit with those all important exemptions!
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Fortyodd2
In normal flight when aft transfer pump warning illuminates, you would turn it off, yes?
If the aft pump NRV is stuck open (SCF single component failure) forward pump is still turned on and drawing amps, but the fuel is going round and round in the main tank.
First indication you would get is an amber warning for the supply tanks (if it's working) followed by a red warning.
Turning on the aft transfer pump will overcome the faulty NRV, put would a Pilot recognise that?
The two supply tanks contain 115ltrs when full. What's really eating at me is only 95ltrs drained by AIB
And that's including any unusable in the main tank.
In normal flight when aft transfer pump warning illuminates, you would turn it off, yes?
If the aft pump NRV is stuck open (SCF single component failure) forward pump is still turned on and drawing amps, but the fuel is going round and round in the main tank.
First indication you would get is an amber warning for the supply tanks (if it's working) followed by a red warning.
Turning on the aft transfer pump will overcome the faulty NRV, put would a Pilot recognise that?
The two supply tanks contain 115ltrs when full. What's really eating at me is only 95ltrs drained by AIB
And that's including any unusable in the main tank.