[SteveG]

A brief story some who operate early Skymasters with mechanical fuel senders might find valuable as it points to a safety of flight issue. Search function, while bringing up numerous issues did not seem to illustrate the point. Last week while traveling down to SnF’ and back I noticed the fuel guage for the port side aux. tank which had heretofore been operating accurately, now seemed to be reading erroneously. After 30 minutes of burn time it was still indicating full and after 55 minutes of burn time it was reading 6 gallons. While contemplating what the problem might be and how much longer I was going to burn it ATC called with the third rerouting of the trip. This distraction took my attention away from fuel management just long enough for the front engine to suck air and extinguish the fire. After switching tanks and, with the help of the boost pump, restarting the motor, I said to myself “Self, lets switch tanks at 6 gallons indicated for the rest of this trip.” On returning home I began to investigate what might be the problem. Checked all wire connections at the sender and guage for security with nothing found. Checked the sender for binding or deformity of the float arm with nothing found. Removed the sender from the tank so as to operate the float arm manually. Now the guage reads perfectly, zero fuel at the bottom stop, full fuel at the upper stop and a linear progression between the two. Well, that’s interesting. Used an abrasive pad to brighten the sender ground strap and attach point and reinstalled the sender in the tank. Voila’, works beautifully. So, the first lesson learned is that these senders fail unsafe or to a full indication if they lose ground connectivity rather than fail safe or to an empty indication. Second lesson, if you think your gauges are reading high, check for a good ground. Third lesson, which of course we all know already, use fuel gauges with a high level of suspicion.