A319/A320 XFR Valves Fault

[fredgrav]

Hi everyone,
was trying to analize QRH procedures in the following situation:

- CTR TK EMPTY
- WING INNER TKS less than 750 Kg each (appr. 25/30' END)
- L/R WING OUTER TKS FULL

ECAM OUTER TKS UNUSABLE + LAND ASAP (red)

After applying QRH - FUEL L + R WING TK LO LVL, if unable to land within 25/30'', could a CIRCUIT BKRS RST (A10+11) be efficient as last resort ?

Many thanks,
fredgrav

[rudderrudderrat]

Hi fredgrav,

Also there's a section on computer resets in the QRH, - page 2.44 which may be relevant.

"Loss of Fuel Quantity Indication OR
Simultaneous triggering of FUEL L TRANSFER VALVE CLOSED and FUEL R TRANSFER VALVE CLOSED, although system display indicates no anomaly."

Then it asks for 3 FQI cbs to be pulled and reset after 5 secs.

Edit. I gather that the FUEL L + R WING TKS LO LVL ECAM will be enhanced and harmonised with the rest of the Airbus Fleets, and will request "FUEL X FEED ON" (open) when the next Flight Warning Computer F6, is installed. (scheduled to be certified by the end of 2010) Which will make all the fuel available to the engine(s) until all the fuel on board is exhausted.

[fredgrav]

Thanx Rudder your answer is more than interesting ! ;)

[Chris Scott]

Hi rudderrudderrat,

I haven’t flown the A320 recently, but am wondering if the FWC mod you refer to will actually provide a solution to the Transfer Valves failure (to open on schedule) that fredgrav is concerned about?

In the past, if memory serves, there has been no connection between the operation of the main fuel crossfeed valve and the transfer valves. The only method available to the crew for opening one or both transfer valves has been to cycle the relevant CBs.

This used to be done for one of two possible reasons:
(1) in the event of one or both valves failing to open on schedule, presumably due to a software problem;
(2) to pre-empt the schedule − e.g., to avoid ice formation on the upper wing surface (outboard) during a turnround.

Are you suggesting that the fuel crossfeed switching may be modified to include a hard signal to the transfer valves? The use of CBs as a routine − and sometimes essential − expedient to correct software problems has been recognised as an undesirable state of affairs ever since we introduced the A320 into service in 1988.

Chris

[rudderrudderrat]

Hi Chris,

No - I hope I haven't confused everyone. The X Feed valve does't have any effect on the transfer valves.

I was making reference to the ECAM procedure, "FUEL L + R WING TKS LO LVL" which asks for X feed "Off" (closed) at present - even when engine out. The change in ECAM will ask for X feed "ON" (open) which will then allow all the fuel (in the inner tanks) to be available to the engine(s).

[fredgrav]

Rudder,
is there a way to get any technical info on the new FWC F6 ? ...

Thanks

[captmilo]

MY friend , easiest way is , jus pull you fqi channel 1 and 2 CB's and your problem will be sorted out . it will reset the Xfer valves .

[ggofpac]

MY friend , easiest way is , jus pull you fqi channel 1 and 2 CB's and your problem will be sorted out . it will reset the Xfer valves .


will that work? anyone confirm plz. Cos the way i read the reset in the qrh sounds like its for an indication problem ( ecam out but system display shows normal transfer valve operation).
Thanks.
(still new on the bus wants to learn more).

[FlightDetent]

Probably yes. One one machine we've had XFR valves issues, after takeoff you'd get XFR VALVE FAULT ecam - outer tank fuel unusable, SD show correct position: CLOSED. At one occasion we did conclude that possible non-opening close to TOD would be a problem. While I (FO) advocated pulling XFR breakers (saw ground engineers do it before) MCC suggested reset of FQI according to troubleshooting manual. Needles to say, it worked perfectly. Further reading in FCOM1 on XFR VALVE operating logic and FWC shown, that one FQI supplied the instruments with correct fuel levels while other channel may have provided incorrect low inner tank fuel values to FWC. FWC realised that under the perceived circumstances XFR VALVES should have been open and while that not being the case triggered the ECAM warning.

To break it down: XFR valves had been closed and operating correctly. FWC thinks that they should be open, based on some obviously incorrect data input as the fuel was plenty. The ECAM warning shows a problem but it is not with XFR VALVEs themselves as confirmed on SD, but with FWC logic. FWC is supplied from FQI, reset FQI and if successful FWC clears the warning immediately.

So, in our case the displayed XFR VALVE FAULT is not pointing you to XFR VALVE problem, it needs to be interpreted as FWC issue. Once you understand that it is clear you start dealing with errorneous FWC inputs and that is FQI channel 2. Just like the trained maintenance experts say.

Sincerely,
FD (the un-real)

[captmilo]

myh frnd , dis is not a procedure anywhere , its jus a self knowledge , an engineer would know this , not many pilots just pull da damn CB , nd theyll reset nd ur indications wil be normal , now some of the new A320 versions have xfer valve CB's , but dont confuse ureself ,dis problem will be sorted out by your FQI CHAN 1 or 2

thank you
happy landings



p.s --0 any other questions ... mail me --- [email protected]

[FlightDetent]

Illegible, sorry.:(

[fredgrav]

Hi everyone,
XFR valves get their input to open from FQI computer, and, at this point, a FQI CBR reset may be successful ... anyway, being the problem electronic in nature, is there any chance to solve it by resetting A10+11 CBRS, should a FQI reset be unsuccessful ?

[Gerd53]

The XFR valves do not get an input to open from the FQIC :=. The input to open comes from the FLSCUs. The input to close indeed comes from the FQIC when starting the refueling.
To open the valves a reset of the cbs on panel 49VU pos. A10/A11 and 121VU pos. M22/M23 may help.
RGDS

[fredgrav]

Hi Gerd53,
you're right sir, but, in spite of the thousands of computer names we're finally put forward, there's often a strict connection between them all. Can a Fuel Level Sensing Control Unit alone give input for valves to open ? If memory serves, it is interfaced with FQIC so that data are first checked in consistency before an input is sent to valves actuators ... :confused:

Best,
fredgrav

[Fargoo]

The FLSCU's command the control relays to power the valves either open or closed.

Although captmilo above chose to write in text speak I believe he is correct in what he's saying.

Great debate though, I can confirm that on the ground tripping and resetting all the transfer valve c/b's does cause them to open. Opening the refuel panel causes them to close again.

I've had c/b's snap due to the plastic going brittle on older Airbus so i'd advise against tripping any in flight unless your procedures or maintrol specifically ask you to.