I cannot get fuel from the aux or ext tanks. I have verified that the vales are aligned and pumps are on but the aircraft still used fuel from main tanks only will not transfer or use fuel from the aux or external tanks.

Have you tried turning the fuel pumps for the main fuel tanks off, so that the fuel pumps for the AUX, and External Tanks will be the only ones working to feed fuel to the engines?

Note. When I tested this out, it worked for me, but the Aux Tank pumps override the External Tank pumps, so I had to turn off the Aux Tank pumps to get the External Tanks to feed the fuel to the engines.

No I Haven't tried that yet, I will try this afternoon or evening and let you know. I assume the procedure would to takeoff using the main tanks then switch over to the aux or external tanks until they are nearly empty.

skmcconnell361 wrote on Nov 7^th, 2017 at 7:35pm:

I assume the procedure would to takeoff using the main tanks then switch over to the aux or external tanks until they are nearly empty.

I also assume that's how it's done. ;)

Yes turning off the main pumps after take off did allow the aux tank to feed the engines, I had a full load with the casualty setup taking medical evacuees out of San Juan, Puerto Rico To Miami and did not have the external tanks installed.