What we get is err on the indicator and it still reads the fuel qty. What happens when we press test is that it goes through a bite and displays all err codes, so almost the same but different.
The essence is that if the error code displayed does not effect the qty indication then no stick checks are reqd by engineering or fuel calculations by burn off by the crew. The indication is unaffected, however as said as there is an error code then an entry should be made and dealt with appropriately.
747 error codes 1, 3 and 6 are considered soft failures that do no affect the FQI. Error codes 2, 4, 5, 7, 8, 9 and 10 are hard faults that will have some form of degradation on the FQI, sometimes it will be blank read 0 or some other erroneous reading, therefore the FQI is unreliable and needs maintenance and creq action.
So with the 737 error codes of 1, 3, 5 and 7 it is a similar scenarion, yes there is an error in the system but it does not affect the qty indication and you can still use the FQI as a reliable source of actual fuel qty. Other codes 2, 4, 6 8 etc do and require action. In either case you should write the snag up and it should be actioned by maintenance either by downgrading the system where stick checks and fuel burn are monitored or in the case of the soft errors you can rely on the FQI as being accurate and no further action is required until fixed within the time scale as dictated by the MEL, say 10 days.
Hope that helps.
