[Jim Smith]

Based on my math all of the fuel used from my last flight came out of only one tank. About 21 gallons for an hour of flight. Both auxiliary tanks were about half-full so I don't think there was any fuel returned. I have externally inspected the fuel valves, went through all positions, and everything appears to be operating properly and stopping in their correct detents. I ran it on the ground for nearly 30 minutes at different power settings and everything is functioning properly, but the run wasn't long enough to determine any uneven fuel burn. I will do a one hour test flight tomorrow and then top it off to see where the fuel is burning from.

It's my understanding the number one cause of Skymaster crashes has been fuel exhaustion. It makes me wonder if there's a possible hidden defect in the system that only materializes under certain conditions. Such condition would most likely be undetectable by the NTSB, especially with all fuel selectors in their correct positions, it would appear that the pilot just accidently exhausted the fuel supply.

Herb (and others) thanks for your replies. Quite frankly, due to the serious nature of this problem I'm quite surprised I've had such little responses.