Fuel Density readings
 

I am an Aircraft Electrician on the Hamburg FAL forA318, A319 And A321

At the moment we have a serious problem with Cadensicons that nobody can seem to put the finger on.

In a nut shell on fuel gauging test the fuel Density readings between the Right, Center & Left wing tanks can very within 0.005- 0.015 on the CFDS.

Our tolorence for sale to the customer is 0.004 between the readings.

Can any of you pilots shed light on this with regards to the readings you see in operation and the tolorence between them.

The supplier tells us there are no fault found on the unit when rejected.

I am not familiar with the systems to which you refer ..... you might consider that density readings may vary with fuel source (origin) and temperature, the latter being affected by mixing fluids as the aircraft is refuelled.

Do you check the SG with a calibrated hydrometer at all ? If

(a) the measuring device is not calibrated and
(b) you don't replicate the calibration conditions to a reasonable extent

then all bets are off and any reading is only an indication of the value sought, accurate to an unspecified greater or lesser degree.

A target variation of 0.004 is laudable but possibly not readily achievable or repeatable in the field ...... perhaps one of our fuel experts might care to comment ?