After flying a brief maintenance test flight which was prefaced by only a quick visual check of fuel on board; the pilot of a C-152 was shocked to learn he had returned with only one gallon of usable fuel in the two tanks.

Narrative

In preparation for a post-maintenance flight to check out a new propeller; I performed a preflight per the Pilot Operating Handbook; including draining and sampling fuel and checking the oil level. We use GATS jars to sample fuel and pour it back into the tanks. As I poured the fuel back into the tanks; I checked the fuel level visually in each tank and saw what I judged to be sufficient fuel for the flight; which I planned to be approximately 1/2 hour. One of the fuel gauges showed just over 5 gallons; which matched my estimate of the fuel in each from looking into the tanks; though the other gauge showed empty.During the climb-out; I became uneasy about the actual amount of fuel in the tank and decided only to do a couple of turns directly over the airport; rather than doing a half hour flight out of the pattern. The airplane performed well. I coordinated with the Tower to descend into the pattern for landing and taxied back to the maintenance area. In the process of discussing the various minor issues I'd noted; we 'dipped' the tanks and I was shocked to see that there was less than a gallon of usable fuel remaining in each wing. This experience has emphasized the need not only to check the fuel level before a flight; but also to quantify the fuel level. Saying 'I have enough fuel' is far different from saying 'this flight requires 5 gallons; and the plane contains 15 gallons.'