Police helicopter crashes onto Glasgow pub: final AAIB report
When the cavitate (they heat up) they show a warning.
The standard practice seemingly being to select the offending pump OFF to extinguish the caution.
The logic in the CPDS is as follows:
Power is applied to the pump via the CB and the corresponding switch and the CPDS internals measure the current via a shunt. A functioning pump with fuel under load requires a certain current.
If after ~ 3 minutes the current is less than the required value the Caption will illuminate on the CAD. If the current value is restored the caption extinguishes immediately and the "watchdog" timer starts again.
You will notice this if you turn the pumps ON on the ground the caption will go out immediately and when you turn the pumps OFF it takes ~ 3 minutes.
The only way to extinguish the caption on the CAD is to have an operating pump transferring fuel. Every time the caption illuminates you will get a Master CAUTION which can be reset but the corresponding caption
on the CAD remains until the situation meets the logic. Doesn't matter what you do with the switch. If the logic is not met the CAD caption is active.
All Master CAUTIONS should be acknowledged and reset so they do not mask the subsequent ones.
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RVDT - I bow to your superior knowledge. However, is that all you got from my post ????
Typical internet troll interested only in finding the defects in postings.
What you also describe is the latest evolution of the pump logic. As I understand, this is not the version that was fitted to this aircraft.
Typical internet troll interested only in finding the defects in postings.
What you also describe is the latest evolution of the pump logic. As I understand, this is not the version that was fitted to this aircraft.
Just a point to note:
"Maybe his supply tanks were indicating FULL, caused by a minute amount of water the capacitance sensors which subsequent to recovery of the helicopter post accident, had dried away."
The amount of water needed to 'short out' the Capacitors was just a small droplet floating around in the fuel that could be pulled into the centre by a swirl in the fuel. However, Capacitors did not need to be dried to regain their function, although generally, this was how they were stored when found U/S. Tests showed that an equally small bump would shift the droplets from contacting both surfaces.
"Maybe his supply tanks were indicating FULL, caused by a minute amount of water the capacitance sensors which subsequent to recovery of the helicopter post accident, had dried away."
The amount of water needed to 'short out' the Capacitors was just a small droplet floating around in the fuel that could be pulled into the centre by a swirl in the fuel. However, Capacitors did not need to be dried to regain their function, although generally, this was how they were stored when found U/S. Tests showed that an equally small bump would shift the droplets from contacting both surfaces.
DB,
The pump logic has always been this way.
As far as being a troll? I am really only concerned about the information put forward by people who clearly do not know the aircraft.
Far from being a troll I have operated and maintained the type for ~ 14 years and of my approximately 8000 hours I have about 650 hours in command on the type.
I am an LAME on the type and also hold an ATPL (H). Recurrency is performed at the manufacturer in Donauworth along with CAT A and MCF (Maintenance Check Flight).
I, like a lot of other people, cannot fathom how someone could get it so wrong unless they were misinformed or lacked adequate knowledge of the systems.
In aviation safety, the devil is in the details. Aviation safety where I come from relies on a blameless culture.
Call me a troll if you wish but personally, I doubt many would agree with you. Or maybe I am wrong - who knows.
What I described is applicable to the serial number of this aircraft.
The pump logic has always been this way.
As far as being a troll? I am really only concerned about the information put forward by people who clearly do not know the aircraft.
Far from being a troll I have operated and maintained the type for ~ 14 years and of my approximately 8000 hours I have about 650 hours in command on the type.
I am an LAME on the type and also hold an ATPL (H). Recurrency is performed at the manufacturer in Donauworth along with CAT A and MCF (Maintenance Check Flight).
I, like a lot of other people, cannot fathom how someone could get it so wrong unless they were misinformed or lacked adequate knowledge of the systems.
In aviation safety, the devil is in the details. Aviation safety where I come from relies on a blameless culture.
Call me a troll if you wish but personally, I doubt many would agree with you. Or maybe I am wrong - who knows.
What you also describe is the latest evolution of the pump logic. As I understand, this is not the version that was fitted to this aircraft.
The standard practice seemingly being to select the offending pump OFF to extinguish the caution.
And nope again.
And nope again.
However, I know Police Pilots who would turn them off in the hover, despite knowing that the caption would disappear when flying away fro the hover. I never used to do this.
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RVDT - I apologise. Having checked I see your explanation is the correct one. However, the point I was trying to make, that may be relevant to this accident, is that as a general practice when the pump cavitated pilots would switch the pump OFF and then acknowledge the caution. This would effectively mean that the pump ends up OFF and there are no immediate indications on the CAD to indicate this. Can we agree on this?
A combination of nose down followed by nose up (hovering), could prompt the pilot to carry out this action for both pumps. Now there is no transfer capability from the Main Tank to the Supply Tanks AND there are no visible indications (other than the switch position) to indicate this.
I am qualified to operate the EC135 but have no operating experience at this point. Hence my poor explanation of the pump logic. Please forgive me for this.
A combination of nose down followed by nose up (hovering), could prompt the pilot to carry out this action for both pumps. Now there is no transfer capability from the Main Tank to the Supply Tanks AND there are no visible indications (other than the switch position) to indicate this.
I am qualified to operate the EC135 but have no operating experience at this point. Hence my poor explanation of the pump logic. Please forgive me for this.
DB - know your audience!
If you had bothered to check, you would know that RVDT has been posting here for many years and the last thing he is is a troll.
I know you want to impart your knowledge to the masses - which is good - but assuming no-one else here meets or exceeds your knowledge and experience is foolish so you should avoid hectoring and patronising your fellow ppruners.
If you had bothered to check, you would know that RVDT has been posting here for many years and the last thing he is is a troll.
I know you want to impart your knowledge to the masses - which is good - but assuming no-one else here meets or exceeds your knowledge and experience is foolish so you should avoid hectoring and patronising your fellow ppruners.
skadi
skadi,
1997? Pre CPDS? CPDS in serials prior to 0120 I think was a retrofit.
The delights of CDS!
1997? Pre CPDS? CPDS in serials prior to 0120 I think was a retrofit.
The delights of CDS!
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Originally Posted by [email protected]
DB - know your audience!
If you had bothered to check, you would know that RVDT has been posting here for many years and the last thing he is is a troll.
I know you want to impart your knowledge to the masses - which is good - but assuming no-one else here meets or exceeds your knowledge and experience is foolish so you should avoid hectoring and patronising your fellow ppruners.
If you had bothered to check, you would know that RVDT has been posting here for many years and the last thing he is is a troll.
I know you want to impart your knowledge to the masses - which is good - but assuming no-one else here meets or exceeds your knowledge and experience is foolish so you should avoid hectoring and patronising your fellow ppruners.
This is what drives me nuts about pprune. By the way, I was not imparting knowledge. I was offering a possible scenario explanation in response to SAS comments.
The point being as always, if you have nothing of any real value to add, don't post just to annoy those of us making and effort.
Purveyor of Egg Liqueur to Lucifer
DB;
I think you need to understand that with the transfer pump(s) switched off and caution acknowledged, the CAD will still be indicating F PUMP FWD or F PUMP AFT on the centre display column,depending on which pump has been switched off.
In normal operation, the only items displayed on the CAD would be PITOT HTR , with S\L LIGHT if switched on.
In the last many minutes of this particular flight, the CAD indications alone presented to the crew should have been PITOT HTR, F PUMP, FWD F, PUMP AFT, PRIME PUMP (1), PRIME PUMP(2), FUEL ... meaning at least three acknowledgements of the master caution. Then of course the Warning Panel indications should also be presenting themselves ...
However, the point I was trying to make, that may be relevant to this accident, is that as a general practice when the pump cavitated pilots would switch the pump OFF and then acknowledge the caution. This would effectively mean that the pump ends up OFF and there are no immediate indications on the CAD to indicate this. Can we agree on this?
A combination of nose down followed by nose up (hovering), could prompt the pilot to carry out this action for both pumps. Now there is no transfer capability from the Main Tank to the Supply Tanks AND there are no visible indications (other than the switch position) to indicate this.
I am qualified to operate the EC135 but have no operating experience at this point. Hence my poor explanation of the pump logic. Please forgive me for this.
A combination of nose down followed by nose up (hovering), could prompt the pilot to carry out this action for both pumps. Now there is no transfer capability from the Main Tank to the Supply Tanks AND there are no visible indications (other than the switch position) to indicate this.
I am qualified to operate the EC135 but have no operating experience at this point. Hence my poor explanation of the pump logic. Please forgive me for this.
The relevant point is the pumps getting switched off and the caption acknowledged which effectively removes it from page 1 of the CAD.
I think you need to understand that with the transfer pump(s) switched off and caution acknowledged, the CAD will still be indicating F PUMP FWD or F PUMP AFT on the centre display column,depending on which pump has been switched off.
In normal operation, the only items displayed on the CAD would be PITOT HTR , with S\L LIGHT if switched on.
In the last many minutes of this particular flight, the CAD indications alone presented to the crew should have been PITOT HTR, F PUMP, FWD F, PUMP AFT, PRIME PUMP (1), PRIME PUMP(2), FUEL ... meaning at least three acknowledgements of the master caution. Then of course the Warning Panel indications should also be presenting themselves ...
DB,
Your points are taken on board and I am no way influenced by what you have pointed out in the past.
Please appreciate that this conversation is a "forum" full of lurkers and listeners who may not appreciate that the information is not "factual".
I am a little concerned as to where you source your info and maybe it needs review.
That is inaccurate and false.
The CPDS CAD Page is divided into 3 columns - SYSTEM 1 - MISC - SYSTEM 2 - Transfer pumps are in the middle MISC column.
Be aware that you would need approximately 9 older and existing MISC Cautions for F PUMP FWD or F PUMP AFT to move to page 2.
The following CAUTION captions are possible in MISC.
XMSN CHIP
TRGB CHIP
XMSN OIL TEMP
XMSN OIL FILT
F PUMP AFT - always on with a non-operating pump
F PUMP FWD - always on with a non-operating pump.
EPU DOOR - Ground only
BAT DISCON - Not likely
EXT POWER - Ground only
There are 3 advisories in green that I can think of -
AIR COND
PITOT HEAT
SEARCHLIGHT
Advisories remain below cautions in the list.
The above list is not complete and may vary accordingly with options and software version and my memory.
DB - with due respect where are you getting the false information?
And further to Sids comments who beat me to it - PRIME PUMP 1 and PRIME PUMP 2 would NOT be in MISC column.
Your points are taken on board and I am no way influenced by what you have pointed out in the past.
Please appreciate that this conversation is a "forum" full of lurkers and listeners who may not appreciate that the information is not "factual".
I am a little concerned as to where you source your info and maybe it needs review.
The relevant point is the pumps getting switched off and the caption acknowledged which effectively removes it from page 1 of the CAD
The CPDS CAD Page is divided into 3 columns - SYSTEM 1 - MISC - SYSTEM 2 - Transfer pumps are in the middle MISC column.
CAUTION messages are listed in the order in which they appear (oldest message on top). If CAUTION messages cannot be displayed on a single page, then '1 of 2', for instance, appears at the top in the central column to indicate that an additional page with CAUTION messages exists. This page can be selected with the SELECT pushbutton. After 15 seconds the system will automatically return to page 1. If a CAUTION message disappears, the corresponding position will remain empty for five seconds, then all the messages below will move up a position. When a new CAUTION message appears, all previously displayed CAUTION messages are deleted and a yellow bar flashes above and below the new CAUTION message. The annunciator MASTER CAUTION illuminates simultaneously on the instrument panel. The crew must confirm the CAUTION message(s) using the switch CDS/AUDIO RES located on the cyclic stick or the SELECT button on the CAD. In case of a CAD failure, the ENTER key on the VEMD must be pressed. The yellow bars are suppressed, all CAUTION messages are displayed in the order in which they appeared and the annunciator MASTER CAUTION extinguishes.
The following CAUTION captions are possible in MISC.
XMSN CHIP
TRGB CHIP
XMSN OIL TEMP
XMSN OIL FILT
F PUMP AFT - always on with a non-operating pump
F PUMP FWD - always on with a non-operating pump.
EPU DOOR - Ground only
BAT DISCON - Not likely
EXT POWER - Ground only
There are 3 advisories in green that I can think of -
AIR COND
PITOT HEAT
SEARCHLIGHT
Advisories remain below cautions in the list.
The above list is not complete and may vary accordingly with options and software version and my memory.
DB - with due respect where are you getting the false information?
And further to Sids comments who beat me to it - PRIME PUMP 1 and PRIME PUMP 2 would NOT be in MISC column.
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RVDT and Sid - I defer to your greater knowledge. I was somehow trying to offer an explanation for Dave's actions. Given what you have pointed out, my point now seems extent. Thanks for correcting me and I apologise for the misleading information. I am not too arrogant to know when I am wrong. So I try harder to be more accurate.
The point being as always, if you have nothing of any real value to add, don't post just to annoy those of us making and effort.
No need to get the hump and I'm not doing it to annoy you
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Originally Posted by [email protected]
No, you are right - my error - point conceded
Purveyor of Egg Liqueur to Lucifer
DB
As for your ramblings in post #478 about the SHED BUSS, Rad Alts and Landing Lamps; I suggest that the next time you get into a 135, switch on the Battery, switch on the Avionics, (leaving the SHED BUSS switch alone) and notice that the Rad Alt and landing lamp are powered.
Granted that any moveable lamp will not be powered, but to be honest what real use is it anyway in a night auto?
Where was it pointing when last switched off, has it possibly reverted to the stored position when switched off. At any height above c100’ what will it actually show you and with any attitude change at the end of the auto (c100’) will it really be of any benefit.
Us mere mortals will probably be having a devil of a time with Nr, looking for somewhere to be aiming for and then gauging the flight path without any need to be faffing around with a switch in the roof (that no more is allowed to have a handy piece of string to identify it) to give us a landing light that we will then need to steer into a practical position.
I for one on take off, position the moveable lamp into the one o’clock low position where I know it will be when I switch it back on; it may be of some use when hurting towards terrafirma, however once I identify the rapidly approaching ground, it is time for an attitude change and in turn back to darkness.
As for your going for a relight, (why have they failed) ... generally operating at 1500-2000 you’ll not be surprised to hear that it won’t be too high on my double engine failure ‘to do’ list for obvious reasons.
I think that’s about all I have to add to this that hasn’t already been covered in the other threads.
Fly safe all
As for your ramblings in post #478 about the SHED BUSS, Rad Alts and Landing Lamps; I suggest that the next time you get into a 135, switch on the Battery, switch on the Avionics, (leaving the SHED BUSS switch alone) and notice that the Rad Alt and landing lamp are powered.
Granted that any moveable lamp will not be powered, but to be honest what real use is it anyway in a night auto?
Where was it pointing when last switched off, has it possibly reverted to the stored position when switched off. At any height above c100’ what will it actually show you and with any attitude change at the end of the auto (c100’) will it really be of any benefit.
Us mere mortals will probably be having a devil of a time with Nr, looking for somewhere to be aiming for and then gauging the flight path without any need to be faffing around with a switch in the roof (that no more is allowed to have a handy piece of string to identify it) to give us a landing light that we will then need to steer into a practical position.
I for one on take off, position the moveable lamp into the one o’clock low position where I know it will be when I switch it back on; it may be of some use when hurting towards terrafirma, however once I identify the rapidly approaching ground, it is time for an attitude change and in turn back to darkness.
As for your going for a relight, (why have they failed) ... generally operating at 1500-2000 you’ll not be surprised to hear that it won’t be too high on my double engine failure ‘to do’ list for obvious reasons.
I think that’s about all I have to add to this that hasn’t already been covered in the other threads.
Fly safe all
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I for one on take off, position the moveable lamp into the one o’clock low position where I know it will be when I switch it back on; it may be of some use when hurting towards terrafirma, however once I identify the rapidly approaching ground, it is time for an attitude change and in turn back to darkness.
Would a constant attitude auto not be appropriate in this type?
Last edited by gevans35; 22nd Nov 2018 at 23:30.
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SilsoeSid, from the GPAO accident report page 75 reads as follows:
"The operator instructs pilots that, if time is available after an autorotation has been entered and the Nr is stable, the shed bus switch should be selected to emerg, to provide power to the steerable landing light and the RADALT, a MAYDAY call should be made and, then, the engines shutdown. The operator recognises that it can be difficult to locate the shed bus switch in an emergency.
Without the RADALT, the pilot did not have accurate height information. Also, he did not have the benefit of a steerable landing light to improve the visual cues. While it was not possible to determine how much this adversely affected his ability to carry out an autorotation and a successful flare recovery, it was apparent that the situation involved attempting a forced landing at night, in a built-up area of Glasgow city centre."
SID - Are you the AAIB are incorrect?
The rest of you post I agree with except the relight reference was in respect to the first engine failing offering a possible explanation why one of the prime pumps was selected ON.I certainly agree with you that attempting a relight in auto below 2,000 feet minimum, is a futile effort.
"The operator instructs pilots that, if time is available after an autorotation has been entered and the Nr is stable, the shed bus switch should be selected to emerg, to provide power to the steerable landing light and the RADALT, a MAYDAY call should be made and, then, the engines shutdown. The operator recognises that it can be difficult to locate the shed bus switch in an emergency.
Without the RADALT, the pilot did not have accurate height information. Also, he did not have the benefit of a steerable landing light to improve the visual cues. While it was not possible to determine how much this adversely affected his ability to carry out an autorotation and a successful flare recovery, it was apparent that the situation involved attempting a forced landing at night, in a built-up area of Glasgow city centre."
SID - Are you the AAIB are incorrect?
The rest of you post I agree with except the relight reference was in respect to the first engine failing offering a possible explanation why one of the prime pumps was selected ON.I certainly agree with you that attempting a relight in auto below 2,000 feet minimum, is a futile effort.
DB
As for your ramblings in post #478 about the SHED BUSS, Rad Alts and Landing Lamps; I suggest that the next time you get into a 135, switch on the Battery, switch on the Avionics, (leaving the SHED BUSS switch alone) and notice that the Rad Alt and landing lamp are powered.
As for your ramblings in post #478 about the SHED BUSS, Rad Alts and Landing Lamps; I suggest that the next time you get into a 135, switch on the Battery, switch on the Avionics, (leaving the SHED BUSS switch alone) and notice that the Rad Alt and landing lamp are powered.
skadi