A320 Precooler outlet Temperature
Thread Starter
Joined: Apr 2007
Posts: 100
Likes: 2
From: the blue yonder
A320 Precooler outlet Temperature
Hello, I Saw this today, I couldn't wrap my head around it.
1. As per FCOM DSC 36-20. the precooler outlet temperature becomes amber in case of overheating or low temperature and low temperature is defined as below 150C with wing anti-ICE on (anti-ice was off ) , why didn't the indication become AMBER? could it be because wing anti-ice was off?
2. Why such a mark contrast between ENG 1 and ENG 2 Pre-Cooler outlet temperatures?
Note this A321
Could someone
A320 Precooler temperature indication
explain it
1. As per FCOM DSC 36-20. the precooler outlet temperature becomes amber in case of overheating or low temperature and low temperature is defined as below 150C with wing anti-ICE on (anti-ice was off ) , why didn't the indication become AMBER? could it be because wing anti-ice was off?
2. Why such a mark contrast between ENG 1 and ENG 2 Pre-Cooler outlet temperatures?
Note this A321
Could someone
A320 Precooler temperature indication
explain it
Joined: Feb 2009
Posts: 944
Likes: 445
From: Austria
OM-B - DSC - 36 - 20 - ECAM Bleed page
"Low temperature is detected (only in flight), if:
- the bleed temperature drops below 150°C,
- the wing anti-ice is on,
- and the pressure regulating valve is in the open position."
So all 3 conditions must be satisfied for the amber indication to show up. If You did not have Wing A/I on, this leaves only two of those, and consequently, there will not be the amber indication.
The precooler is fed cooling air from a fan air inlet, governed by a butterfly valve. This valve is driven via some pulleys connected by a twisted wire rope with an eye at each end. I once saw such a picture inflight caused by one of the eyes broken out of the (quite flimsy looking) pulley arm. That caused the butterfly valve to default to fully open, an excessive amount of fan air rushing through the precooler and, consequently, a too low precooler outlet temperature.
MEL 36-11-04A applied and required disabling the onside bleed system as per any of the subpoints of MEL 36-11-01.
"Low temperature is detected (only in flight), if:
- the bleed temperature drops below 150°C,
- the wing anti-ice is on,
- and the pressure regulating valve is in the open position."
So all 3 conditions must be satisfied for the amber indication to show up. If You did not have Wing A/I on, this leaves only two of those, and consequently, there will not be the amber indication.
The precooler is fed cooling air from a fan air inlet, governed by a butterfly valve. This valve is driven via some pulleys connected by a twisted wire rope with an eye at each end. I once saw such a picture inflight caused by one of the eyes broken out of the (quite flimsy looking) pulley arm. That caused the butterfly valve to default to fully open, an excessive amount of fan air rushing through the precooler and, consequently, a too low precooler outlet temperature.
MEL 36-11-04A applied and required disabling the onside bleed system as per any of the subpoints of MEL 36-11-01.
Thread Starter
Joined: Apr 2007
Posts: 100
Likes: 2
From: the blue yonder
OM-B - DSC - 36 - 20 - ECAM Bleed page
"Low temperature is detected (only in flight), if:
- the bleed temperature drops below 150°C,
- the wing anti-ice is on,
- and the pressure regulating valve is in the open position."
So all 3 conditions must be satisfied for the amber indication to show up. If You did not have Wing A/I on, this leaves only two of those, and consequently, there will not be the amber indication.
The precooler is fed cooling air from a fan air inlet, governed by a butterfly valve. This valve is driven via some pulleys connected by a twisted wire rope with an eye at each end. I once saw such a picture inflight caused by one of the eyes broken out of the (quite flimsy looking) pulley arm. That caused the butterfly valve to default to fully open, an excessive amount of fan air rushing through the precooler and, consequently, a too low precooler outlet temperature.
MEL 36-11-04A applied and required disabling the onside bleed system as per any of the subpoints of MEL 36-11-01.
"Low temperature is detected (only in flight), if:
- the bleed temperature drops below 150°C,
- the wing anti-ice is on,
- and the pressure regulating valve is in the open position."
So all 3 conditions must be satisfied for the amber indication to show up. If You did not have Wing A/I on, this leaves only two of those, and consequently, there will not be the amber indication.
The precooler is fed cooling air from a fan air inlet, governed by a butterfly valve. This valve is driven via some pulleys connected by a twisted wire rope with an eye at each end. I once saw such a picture inflight caused by one of the eyes broken out of the (quite flimsy looking) pulley arm. That caused the butterfly valve to default to fully open, an excessive amount of fan air rushing through the precooler and, consequently, a too low precooler outlet temperature.
MEL 36-11-04A applied and required disabling the onside bleed system as per any of the subpoints of MEL 36-11-01.
Joined: Feb 2009
Posts: 944
Likes: 445
From: Austria
Leaving aside the plethora of data the aircraft gathers and sends to maintenance without involving flight crew:
If You were to decide that this indication merits a test of wing A/I, switch it on and wait for the amber warning. Once You see this, it is sufficient for a writeup in the logbook.
The other, low-key, method would be to give Your maintenance a heads-up via the phone and tell them of such an odd indication. This may well result in them coming out to see You after landing and handling the issue just like with an official writeup.
By the way, when I had that issue, I was told that repairing this torn-out eye would take a surprisingly long time: obtaining a new set of pulley arms and crimping the rope into it to achieve the correct length is not that easily done. Our engineers chose to drag the aircraft into the hangar for that instead of doing a quick repair on the apron. On a PW1000G, the valve is sitting to the right of the engine pylon just behind the fan stator vanes; accessing it requires an opening of the fan cowls.
If You were to decide that this indication merits a test of wing A/I, switch it on and wait for the amber warning. Once You see this, it is sufficient for a writeup in the logbook.
The other, low-key, method would be to give Your maintenance a heads-up via the phone and tell them of such an odd indication. This may well result in them coming out to see You after landing and handling the issue just like with an official writeup.
By the way, when I had that issue, I was told that repairing this torn-out eye would take a surprisingly long time: obtaining a new set of pulley arms and crimping the rope into it to achieve the correct length is not that easily done. Our engineers chose to drag the aircraft into the hangar for that instead of doing a quick repair on the apron. On a PW1000G, the valve is sitting to the right of the engine pylon just behind the fan stator vanes; accessing it requires an opening of the fan cowls.
Joined: Sep 2001
Posts: 1,030
Likes: 262
From: Blighty
A post flight report may highlight the fault but you would have to ask your engineers to attend. The PFR may show a failure condition with an associated trouble shooting code that would be used to fault find in the TSM.
Joined: Jan 2012
Posts: 159
Likes: 0
From: Holding at DESDI
You didn't get the BLEED LO TEMP caution because WAI wasn't switched on.
This low temp phenomenon happens when the fan air valve is stuck open and thus cooling bleed air to the max.
The PFR will usually show a fan air valve thermostat or bleed sense line error.
Cold bleed air is not an issue for the packs, so no caution is thrown up if wing anti ice is not required. This is why it's a good idea to keep monitoring system pages regularly.
This low temp phenomenon happens when the fan air valve is stuck open and thus cooling bleed air to the max.
The PFR will usually show a fan air valve thermostat or bleed sense line error.
Cold bleed air is not an issue for the packs, so no caution is thrown up if wing anti ice is not required. This is why it's a good idea to keep monitoring system pages regularly.
