MGL Avionics Stratomaster Ultra “L” Owner’s manual
Page 73
The Stratomaster Ultra is shipped with the Fuel sender calibration set for the jet installed. In a
good installation you can expect about +/- 3% maximum flow reading error with this factor.
You can calibrate the flow sender yourself to a higher degree of accuracy if you so desire.
Recommended procedure to calibrate the fuel flow sender:
Note: You must disable the Fuel Level sender if you have one installed first.
Fill your tank exactly to a known level (for example 50 liters).
Set your fuel level to 50 liters using the Main Menu. If required you may have to disable the fuel
level sender first using the Mode Menu.
Fly your aircraft for a period that you know will use approximately 20 liters of fuel. The exact fuel
burn is not important, just burn about 20 liters of your fuel.
At the end of your flight the Stratomaster Ultra should give you a reading of how much fuel you
have left – the reading should be about 30 liters left.
Now place your aircraft in exactly the same position that you used when you first filled the tank
and refill the tank to 50 liters using a measuring jug. You should find that you need 20 liters of fuel
to refill to 50 liters.
If you find that the Stratomaster under or over reads the fuel used, you should perform a simple
adjustment of the Fuel Flow sender calibration factor. This is outlined in the Owners Manual.
Example:
Actual fuel used: 21.5 liters, Stratomaster fuel burn calculated 29.7 liters left in tank. This means
the Stratomaster measured 50-29.7 = 20.3 liters. We are under reading by 1.2 liters.
Default calibration factor in Fuel Flow setup (Basic device setup menu) = 208.
Let the corrected calibration factor be X.
X = (21.5 * 208) / 20.3
X = 220.29
The closest setting you can enter as factor is 220. Enter it into the unit and you are done !
Repeat the above procedure to verify that your flow sender is now reading correctly.
Please note:
Before you calibrate the flow sender ensure there are no problems with your installation. We find
the senders are very accurate if everything is installed and working properly. If your fuel burn
indication is out by a large amount you have a problem that you should not attempt to fix by
fiddling with the calibration factor !
Please ensure that no fuel vapor can be trapped inside the sender housing in the form of bubbles.
Due to the low fuel flow rates the bubbles will prevent the tiny impeller from turning freely, You
can verify the turning of the impeller. You should notice three dark spots that are just visible in the
inside of the fuel flow sender. These are small magnets that are attached to the impeller. With
fuel flowing you should see the magnets turning.
The best defense against vapor bubbles is to install the flow sender in such a way that the
bubbles can escape. The easiest way is to point the outlet upwards and the inlet (with the jet)
downwards.
Another possible problem is the fuel sender jet. When you install it, do not damage it. Use a drill
bit of suitable diameter to push the jet all the way the opening of the jet must be just in front of the
impeller.
