EC135
Joined: Jul 2006
Posts: 17
Likes: 0
From: UK
As I understand it the system records (and retains) events of greater than 66% and then greater than 78%. It retains the % figure and duration for the life of the aircraft, both by flight number and total time in the >66% and >78% areas.
As I interpret the book the 50-66% area is purely a caution area and no maintenance action is required.
As I interpret the book the 50-66% area is purely a caution area and no maintenance action is required.
Joined: May 2011
Posts: 1
Likes: 0
From: United States
EC 135 - stupid question
Given "up to 59.5 kg" unusable if the forward transfer pump fails...
How about "no fail indication" (i.e. caution) of a forward transfer pump? No light? What's the possibility of this occurring?
Our EC 135 'seems' to transfer fuel normally until about 27 gallons. At that point, the supply tanks start depleting. I am told that other tail numbers have this same functionality? However, other ships reportedly use all their MAIN fuel to ZERO. The later seems normal. Correct?
Does your main fuel always go to ZERO - BEFORE the supply tanks begin to be depleted.
However, if during this anomaly (i.e., with supply tanks depleting as the MAIN fuel goes below 27 gallons), the forward, then aft transfer caution lights illuminate, would this not suggest that the forward and aft transfer pumps are functioning properly - but the MAIN FUEL indication is OUT OF CALIBRATION?
Thanks for your expertise.
How about "no fail indication" (i.e. caution) of a forward transfer pump? No light? What's the possibility of this occurring?
Our EC 135 'seems' to transfer fuel normally until about 27 gallons. At that point, the supply tanks start depleting. I am told that other tail numbers have this same functionality? However, other ships reportedly use all their MAIN fuel to ZERO. The later seems normal. Correct?
Does your main fuel always go to ZERO - BEFORE the supply tanks begin to be depleted.
However, if during this anomaly (i.e., with supply tanks depleting as the MAIN fuel goes below 27 gallons), the forward, then aft transfer caution lights illuminate, would this not suggest that the forward and aft transfer pumps are functioning properly - but the MAIN FUEL indication is OUT OF CALIBRATION?
Thanks for your expertise.
Joined: Sep 2000
Posts: 1,605
Likes: 6
From: UK
On ours the forward fuel pump caption comes on anywhere between 100kg - 150kg if we are steady in the hover.
As for the supply tanks running down this can happen when the main tank is showing 20-40kg.
The way I understand it the forward fuel pump feeds No1 Supply and the Rearward feeds No.2 Supply. Which would make sense with what you have been noticing.
Clear as mud?
As for the supply tanks running down this can happen when the main tank is showing 20-40kg.
The way I understand it the forward fuel pump feeds No1 Supply and the Rearward feeds No.2 Supply. Which would make sense with what you have been noticing.
Clear as mud?
Purveyor of Egg Liqueur to Lucifer
Joined: Nov 2002
Aviation Qualifications: ATPL
Posts: 4,752
Likes: 64
From: Alles über die platz
IIRC,
Both transfer pumps are connected to a common transfer pipe that transfers fuel from the main tank to both supply tanks equally. If one pump should fail, or is switched off when for example the caption comes on, the remaining transfer pump will still supply fuel to the transfer pipe and in turn to both supply tanks.
One transfer pump can supply fuel at a rate that means that the supply tanks will not run dry before the main.
Or something like that !
Both transfer pumps are connected to a common transfer pipe that transfers fuel from the main tank to both supply tanks equally. If one pump should fail, or is switched off when for example the caption comes on, the remaining transfer pump will still supply fuel to the transfer pipe and in turn to both supply tanks.
One transfer pump can supply fuel at a rate that means that the supply tanks will not run dry before the main.
Or something like that !
Purveyor of Egg Liqueur to Lucifer
Joined: Nov 2002
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From: Alles über die platz
No worries B.Stuff,
I wouldn't get too hung up about the quantities when the cautions come on, we landed yesterday with 15 kg in the main with no cautions throughout. Normally at those levels I'd expect the fwd to come on when on approach/taxi. I guess the combination of wind, ac attitude and CoG position meant both pumps still pumping throughout. Both supply tanks still full.
Isn't it funny that when that balance ball spirit level thingy and nice little amber triangle on the PFD point to the right, the right hand supply tank reads a bit low, regardless of main contents
I wouldn't get too hung up about the quantities when the cautions come on, we landed yesterday with 15 kg in the main with no cautions throughout. Normally at those levels I'd expect the fwd to come on when on approach/taxi. I guess the combination of wind, ac attitude and CoG position meant both pumps still pumping throughout. Both supply tanks still full.
Isn't it funny that when that balance ball spirit level thingy and nice little amber triangle on the PFD point to the right, the right hand supply tank reads a bit low, regardless of main contents
Joined: Sep 2000
Posts: 1,605
Likes: 6
From: UK
SS
your quite right the cautions come on at random since the pumps IIRC need two minutes of running dry before they cautions come on usually by then we changed attitude again and the pumps got a suck of fuel again restarting the clock again if you know what I mean.
Cracking helicopter though.
your quite right the cautions come on at random since the pumps IIRC need two minutes of running dry before they cautions come on usually by then we changed attitude again and the pumps got a suck of fuel again restarting the clock again if you know what I mean.
Cracking helicopter though.
Purveyor of Egg Liqueur to Lucifer
Joined: Nov 2002
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From: Alles über die platz
Shocking !
Heard about it, talked about the rumour, but never experienced it, until that is this morning.
Trying to balance the blaring radios, one by one as the calls came in, and my metal watch strap must have rested on the end of the collective...ZZapp!!
A cracking shock that certainly alerts the senses during the umpteenth orbit round a dimly lit church in the middle of nowhere in the dark.
Anyone else admitting having had the collective shock, or will you just snigger at the thought of me bolting upright going..."What the flip!"
Trying to balance the blaring radios, one by one as the calls came in, and my metal watch strap must have rested on the end of the collective...ZZapp!!
A cracking shock that certainly alerts the senses during the umpteenth orbit round a dimly lit church in the middle of nowhere in the dark.
Anyone else admitting having had the collective shock, or will you just snigger at the thought of me bolting upright going..."What the flip!"
Joined: Aug 2001
Posts: 696
Likes: 10
From: Shropshire
Hi Pilot 10000
We regularly land with 80-90kg of fuel remaining and often see the following sequence:
In the cruise, fuel decreases till the aft pump is uncovered, followed by aft fuel pump light a little later. Reach up, switch off aft fuel pump.
Approaching final, gentle decelerative attitude to reduce speed. Front pump becomes uncovered. No warning light because of the inbuilt delay but fuel now not being transferred.
Supply tank contents drop, followed by FUEL caution and then finally the fwd pump caution illuminates.
That may offer an explanation for what you see.
Cheers
TeeS
We regularly land with 80-90kg of fuel remaining and often see the following sequence:
In the cruise, fuel decreases till the aft pump is uncovered, followed by aft fuel pump light a little later. Reach up, switch off aft fuel pump.
Approaching final, gentle decelerative attitude to reduce speed. Front pump becomes uncovered. No warning light because of the inbuilt delay but fuel now not being transferred.
Supply tank contents drop, followed by FUEL caution and then finally the fwd pump caution illuminates.
That may offer an explanation for what you see.
Cheers
TeeS
Joined: Jul 2010
Posts: 55
Likes: 0
From: The American Steppe
Does not the fuel xfer pump switch itself off after running dry for three minutes? Or am I misremembering...maybe the Caution light means it already has been dry for three minutes? Can't look it up here.
Joined: Feb 2006
Posts: 1,067
Likes: 40
From: On the big blue planet
No, the Caution just indicates, that the pump is running dry for a certain time and has to be switched off.
In the early times of the 135 there was no such time delay. the Caution came up as soon as the pump went dry. Very disturbing when doing checkrides or other flight with many attitudechanges and the fuel comes well below 100kg.....
skadi
In the early times of the 135 there was no such time delay. the Caution came up as soon as the pump went dry. Very disturbing when doing checkrides or other flight with many attitudechanges and the fuel comes well below 100kg.....
skadi
Joined: Nov 2006
Posts: 1,951
Likes: 90
From: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
Sid,
Go ask you engineer how the TXPDR goes into STBY or other bits and bobs that require Squat or WOW switching.
Normal.
Go ask you engineer how the TXPDR goes into STBY or other bits and bobs that require Squat or WOW switching.
Normal.
Purveyor of Egg Liqueur to Lucifer
Joined: Nov 2002
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From: Alles über die platz
Thanks RVDT, fully aware of the technical side, which you may have been able to pick up in my post, ("my metal watch strap must have rested on the end of the collective...")
Fyi, our system is setup for a 5 second switchover from ALT-GND mode.
All I wondered was whether or not anyone else was prepared to admit to being zapped.
Fyi, our system is setup for a 5 second switchover from ALT-GND mode.
All I wondered was whether or not anyone else was prepared to admit to being zapped.
Joined: Jan 2006
Posts: 482
Likes: 44
From: 3nm SE of TNT, UK
Never been zapped but I have noticed the odd spark during the Check A. On Police machines, it is also the switch that allows the crew to eject a video tape from the Britannia Recorders when the aircraft is on the ground.