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HAWK21M
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B752 Fqis Process Reliability

Thu May 18, 2006 2:38 am

How Reliable is the FQIS Processor on the B752.
Any Memories of needing to Override the Fuelling valves.
regds
MEL

[Edited 2006-05-17 19:38:51]
I may not win often, but I damn well never lose!!! ;)
 
atlamt
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RE: B752 Fqis Process Reliability

Thu May 18, 2006 4:00 am

The fueling system itself is pretty reliable. The indication system is another story. We get fuel qty bite messages on a regular basis. Most of the time when you bite the box it verifies no faults are present. Reset the box and go flying.

We have gone to a new style of processor and it has helped but didn't completely fix the problem.
Fwd to MCO and Placard
 
Tristarsteve
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RE: B752 Fqis Process Reliability

Thu May 18, 2006 4:11 am

FGIS Bite maint messages are quite common, but the system itself is very reliable. One feature of the B757 is that when you dial up 6000kg on the preselect, it stops with 6000kg in the tank. I think it is the only aircraft I work on which is so precis. Note that the older B757s (pre about 1998) refuel very slowly. It can take 20 mins to get to full wings ( about 13200kg), but about the same time to get to full tanks!.
I can only remember once doing a manual override of a refuel valve in 20 years. Even with a gauge failure the valves still open using the refuel panel switches.
One tip, if no fuel goes in it can be the overfill system at fault. Try pressing the overfill reset. If the fuel flows, then stops again when you let go then you can keep the button pushed in with a Shell water detector metal container. Get one from the refueller and bend it slightly and you cab wedge the button in. Saves your fingers. This happens about 4 times a year.
 
fr8mech
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RE: B752 Fqis Process Reliability

Thu May 18, 2006 4:31 am

I've opened plenty of fuel valves using the manual override feature. Simple and quick. Try to remember, it goes much easier with pressure off the manifold.

Fuel Qty Bite messages are rather common, Fuel Qty Channel much less so.
When seconds count...the police are minutes away.
 
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HAWK21M
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RE: B752 Fqis Process Reliability

Thu May 18, 2006 8:36 pm

Quoting Tristarsteve (Reply 2):
One tip, if no fuel goes in it can be the overfill system at fault. Try pressing the overfill reset. If the fuel flows, then stops again when you let go then you can keep the button pushed in with a Shell water detector metal container. Get one from the refueller and bend it slightly and you cab wedge the button in. Saves your fingers. This happens about 4 times a year.

What was the Snag Rectification.
Replaced Overfill Sensor.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: B752 Fqis Process Reliability

Fri May 19, 2006 2:32 am

Quoting HAWK21M (Reply 4):
What was the Snag Rectification.
Replaced Overfill Sensor.

Usually the FQIS computor at fault.
 
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HAWK21M
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RE: B752 Fqis Process Reliability

Fri May 19, 2006 6:35 pm

Quoting TristarSteve (Reply 5):
Usually the FQIS computor at fault.

Is the FQIS Processor snag prone.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
dl757md
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RE: B752 Fqis Process Reliability

Fri May 19, 2006 8:30 pm

Quoting HAWK21M (Reply 4):
What was the Snag Rectification.
Replaced Overfill Sensor.

The first thing you want to do is see if you get any fuel out of the surge tank sump drains. I've gotten as much as a gallon out of them and it fixes the problem. In my experience this has been the cause about 30% of the time.

DL757Md
757 Most beautiful airliner in the sky!
 
Buzz
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RE: B752 Fqis Process Reliability

Fri May 19, 2006 9:16 pm

Hi again Hawk21M, Buzz here. I've seen a lot of single channel messages for densitometer problems. But the 757 fuel qty system just keeps chugging along.

I haven't had the problems the other guys have run into, once in a while hear of it happening.
g'nite
 
fr8mech
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RE: B752 Fqis Process Reliability

Fri May 19, 2006 9:20 pm

Quoting HAWK21M (Reply 6):
Is the FQIS Processor snag prone.

No, people just like to shoot the messenger. Drain the fuel out of the tank and move along. Occasionally a bad sensor, I also see to recall a relay we've replaced before.

A chronic problem was the D1, D2, D3 messages on the FQIS processor. Basically telling you the densitometer was bad. Used to be radioactive, don't think it is anymore. Problem seems to have gone away also.
When seconds count...the police are minutes away.
 
A/c train
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RE: B752 Fqis Process Reliability

Sun May 21, 2006 3:46 am

lost power completely to the refuel panel once and had to open refuel valves manually
 
fr8mech
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RE: B752 Fqis Process Reliability

Sun May 21, 2006 4:43 am

Here's a quick tidbit of information:

When the fuel panel door is opened, some people will slam it open in order to go passed the detents. This slamming may cause damamge to the bulbs installed on the door. If the bulb filiment shorts, not breaks and opens, but shorts to the base, it may cause the FQIS processor to fail. Seen it, lived it, learned a big lesson from it.
When seconds count...the police are minutes away.
 
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HAWK21M
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RE: B752 Fqis Process Reliability

Sun May 21, 2006 6:59 pm

Quoting Fr8Mech (Reply 9):
Basically telling you the densitometer was bad. Used to be radioactive, don't think it is anymore. Problem seems to have gone away also

There are two Manufacturers of the Densitometers used on the B752.Of which one is considered Radioactive.

Quoting A/c train (Reply 10):
lost power completely to the refuel panel once and had to open refuel valves manually

What was the rectification finally.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
A/c train
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RE: B752 Fqis Process Reliability

Sun May 21, 2006 8:52 pm

Hi HAWK, well the night shift found a damaged wire going to the refuel panel, that loom that runs stupidly close to the slat drive shafts, carried out the repair and the refuel panel functioned satis, does anyone else think that wiring loom behined the refuel panel runs a little close? has it been SB'd out of the problem?
 
fr8mech
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RE: B752 Fqis Process Reliability

Sun May 21, 2006 10:16 pm

Quoting HAWK21M (Reply 12):
Of which one is considered Radioactive

I don't think either are emmiters anymore.
When seconds count...the police are minutes away.
 
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HAWK21M
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RE: B752 Fqis Process Reliability

Mon May 22, 2006 1:55 pm

Quoting Fr8Mech (Reply 14):
I don't think either are emmiters anymore.

What caused the change.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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