CRJ Manual Xflow issue

[mamba20]

LOL nope, but I do know a few words of Oh Canada but I think I got that off a molson bottle.

 

[Beanie]

Thanks Mamba and EDCT. I am trying to get more info on it, like the warning you get, but that is exactly the problem I am talking about.

 

[DrewBlows]

Hmmm... that's the damndest thing.

I don't know how to get around that, I'm not going to wait 30 seconds and then forget to turn on the manual x-flow when I get interupted by who-knows-what. I guess I'll just take my chances. If and when it happens I'll be happy that we already blocked out, then tell the captain that I've read about it on flightinfo.

 

[dbert]

I know, i flew them for 7 years and only had it happen once, and it was the first known one, but not the last. It is a known problem, and I have seen other operators service bulletins and procedures for it. I would like the refresher course on it. Anyone?

Just to be sure you are talking about the 7/900 right? I was not aware of the problem but will keep an eye out.
Not to threadjack, but can anyone tell me why auto crossflow is inhibited (manual) during takeoff? I've heard some weird explanations that included crashing on takeoff and pumping all your fuel towards a ruptured tank.

 

[dbert]

Service letter 28-007 says:
​

​

​

PURPOSE:​

To provide the operator some guidance in avoiding unnecessary troubleshooting of possible
“XFLOW PUMP” caution message displayed on ground or in flight.​

DISCUSSION:​

Operators have reported many events where the “XFLOW PUMP” caution message was
displayed during ground taxi manoeuvre or in flight. It was reported that when the message is
posted on ground in most cases it occurred after the selection of the xflow auto override
(manual mode). In flight, the message seems to be simply displayed when the system operates
normally in the automatic mode. It was also reported that in some cases, the message cleared
itself after few minutes following appropriate QRH action from the flight crew.
When an event is reported, maintenance personal have conducted the following troubleshooting
steps in order to identify the cause. First action made was the reset of the system by pulling the
respective circuit breakers of the fuel computer (FQGC) and/or the xflow pump. In most
cases, reoccurrence of the fault was not seen following the reset. Another action that
maintenance sometime did, was to replace either the FQGC or the pump, taking in
consideration that something could be possibly faulty with the unit.​

​

However, Intertechnique has recently informed Bombardier Aerospace that the majority of the
rejected/returned above components were found having no faults related to this issue.
To further the investigation into EICAS “XFLOW PUMP” caution messages, a data sheet has
been prepared and included in Appendix A. This data sheet is necessary to capture all
information pertaining to the EICAS “XFLOW PUMP” message and will help better
understand the fault and the maintenance actions that are carried out.
Review of the weekly Dispatch Interruption report demonstrates occasional events of
“XFLOW PUMP” message with both xflow fail switch lights reported on. This scenario is
normally the result of a manual override command with the L-R xflow switch lights inadvertently
engaged. Normal operation of the manual mode only required the L or R xflow switch light
selection. When both xflow switches are selected simultaneously it remove power from the
xflow pump, then the “XFLOW PUMP” caution message is displayed with both xflow switch
lights illuminated. To disable the fault either one of the xflow switches or the auto override
switch need to be deselected.​

BOMBARDIER ACTION:​

Following recent implementation of a retrofit with a hardware modification addressing tolerance
with the motor pump, there are still occurrences of xflow pump failure reported by operator on
post modified aircraft.
Intertechnique has been requested to reinitiate their investigation to identify definitively root
cause of the issue. The exercise now consists to focus with a software modification on either
the fuel computer (FQGC) or any other components related with the system.
Further information will be given to the operators through the ISE CRJ700/900 Action Register
item 2840-5.​

OPERATOR ACTION:​

To minimize unnecessary removal of FQGC or xflow pump, Bombardier Aerospace invites the
maintenance personal and flight crew, whenever possible, to perform the following action to
clear a “XFLOW PUMP” caution message displayed on ground prior take-off.
1. Select/verify XFLOW AUTO OVERRIDE is not in MAN (auto mode).
2. Open and close the FUEL SYST CONT circuit breakers (CB1-M11 & CB2-
U11).
3. If message still present, open and close the CROSSFLOW PUMP circuit breakers
(CB1-S5 & CB2-R7).
4. Confirm the “XFLOW PUMP” caution message is not shown.
5. Select the XFLOW AUTO OVERRIDE PBA to MAN (manual mode).
6. After 2 minutes minimum, verify that the “XFLOW PUMP” is not displayed.
7. If the “XFLOW PUMP” caution message comes back on, further troubleshooting
to be performed per normal procedure.​

 

[mullet]

disregard. beat me to it.

 

[Beanie]

Thanks you guys, I knew I could count on ya....Now does anyone have specific flight crew guidance, in SOP's for instance, that gives procedures for avoiding this problem? I think what I had read before said to not select the Xflow to manual if it was close to being done. Can't remember if there was any specific amount like withing 75 lbs of shutting off, or if it was just "close to being 50lbs above". Any more brainiac input would be appreciated.

 

[Beanie]

Just to be sure you are talking about the 7/900 right? I was not aware of the problem but will keep an eye out.
Not to threadjack, but can anyone tell me why auto crossflow is inhibited (manual) during takeoff? I've heard some weird explanations that included crashing on takeoff and pumping all your fuel towards a ruptured tank.

It is a regulation required by the FAA.

 

[CFIT]

It is a regulation required by the FAA.

Correct, useless, pointless, and without merit, but none the less correct.
Exactly what you can expect from the FAA.

 

[dbert]

It is a regulation required by the FAA.

Sorry I asked.