Champion Citabria 7ECA
Flight Crew Private
Flight Crew Last 90 Days 5; Flight Crew Total 173; Flight Crew Type 24
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Flight Crew Overcame Equipment Problem; Flight Crew Landed As Precaution; Flight Crew Diverted
Human Factors; Aircraft
After conducting a pleasure flight to [ZZZ]; I refueled the aircraft at [ZZZ] prior to starting my return trip to [ZZZ1]. Approximately 20 minutes into the flight; having climbed to my cruise altitude of 3;500 feet; I observed that while my right fuel gauge read full as expected; the left gauge was reading about 3/4 of a tank. I immediately diverted to the nearest airport [ZZZ2]; (about 15nm from my position when I noticed the issue) for a precautionary landing. Upon landing; I discovered a large amount of blue dye stains on the right wing; and that the right fuel cap was slightly crooked. When I physically removed and reinstalled the cap; it was no longer crooked. Despite double-checking the caps after fueling at [ZZZ1]; I did not notice the issue with the cap at that time.Based on the amount of fuel I added at [ZZZ2] to top off the aircraft (~14 gallons) and the approximate duration of the flight; I believe that I was losing a gallon of fuel overboard about every 2-3 minutes; and that when I landed at [ZZZ2]; I had approximately 10 minutes of fuel remaining in the left tank.
Citabria 7ECA pilot reported he lost fuel out of a tank that had the cap improperly secured.