My DA42 is fitted with ‘normal’ fuel qty transducers that are quite accurate (except in the range about halfway, but that’s a different story). In addition there is a ‘fuel remaining’ indicator, that uses a pilot pre-set fuel qty value and uses the flow meters to calculate how much fuel is left which is known to be very accurate. Both ways of determining qty have always corresponded perfectly, however lately, and rather abruptly I am now consistently seeing a deviation between the two. The faulty indicator is the one that uses the flow meters. Quite a constant and significant deviation of 5 gallons on an amount used of about 65 gallons, so almost 8%. A matter of recalibrating one or both flow meters maybe, or can they not be calibrated and is one (or both) just faulty and needs to be replaced?
Forgot to mention that the fuel flow indicators indicate the same flow in flight, and indicate the same rate that I’ve always seen..
Puzzling, no?
AIUI a G1000 system contains
If the fuel flow comes from the totaliser (and not some “fuel pressure proxy” gauge like is the case on all the old engines) and it is right, then the totaliser transducer is fine.
So where are you seeing the discrepancy?
Hmmmm, 65 USG means you are using the nacelle tanks as well as the mains. Are you saying that your fuel flow system is under/over-reading compared with the actual amount of fuel you have used (i.e. measured when you fill the tanks)?
The capacitive fuel level meters are correct. The fuel totaliser shows 8% more than what’s actually in the tanks.
Aaah, the totaliser just needs an adjustment.
Dave_Phillips wrote:
Aaah, the totaliser just needs an adjustment.
That would be strange, as nothing seems to have changed from Aart’s introduction and it indicates normal fuel flow, only total full is incorrect if I understand correct?
Maybe one of the fuel flow transducers is intermittend (e.g. correct fuel flow indication when checked while incorrect total used)
How do you adjust a fuel totaliser?
If it reads the right flow rate then the K factor is right.
What it’s not: losing fuel in flight from a leak downstream from one FF meter because the quantity in each tank remains the same..
Could the fuel flow reading on one engine be 8% out without you noticing it?
If so, then the K factor in one of the totalisers might have got corrupted.
