On the checkride for my private pilot certificate 20 years ago, the examiner handed me a temporary certificate and said, “Here’s your ticket to learn.” Those words have stayed with me over the years and have proved true on many occasions.
I had just purchased my very own warbird, a 1954 Yakovlev Yak-18, in Las Vegas, Nevada. A beautiful sunny Sunday morning was all the invitation I needed to take the new airplane up for a flight.
On the way to my hangar I ran into my friend Jim, who was about to fly his North American AT-6 up to Reno for the National Championship Air Races. He suggested that if I could quickly get my Yak-18 airborne we could fly formation for part of the trip to Reno.
I called the fuel truck and headed over to my hangar. I removed the fuel access covers and fuel caps from both of the Yak’s fuel tanks. About 10 minutes later, the lineman had topped off the tanks, and as I was sealing the port tank, he said, “I already got the starboard tank for you.”
I thanked him and went over to the starboard wing and installed the access panel that covers the fuel cap.
Jim was about five minutes from engine start, so I figured I could get airborne first and loiter near the field. The takeoff was typical except that, on the downwind leg, there was a faint smell of avgas in the cockpit. Having over-fueled the aircraft previously, I surmised that some gas had spilled into the tank bays and it would dissipate shortly. I climbed to 4,000 feet and circled about four miles north of the airport while waiting for Jim.
Jim took off and I joined up on his port wing for some formation practice. At this point, the fuel odor became more noticeable. I scanned the instruments and saw nothing out of the ordinary. I glanced at the wing fuel gauges and fuel access panels and saw nothing alarming. The odor was very strong now. I told Jim I had a minor problem and needed to return to the airport. I bid him good luck and turned back. Calling the tower at four miles out I was cleared for Runway 25L. I didn’t declare an emergency as the pattern was empty and the problem did not seem severe.
On final approach the smell of avgas became overpowering. To compensate I opened the sliding canopy. I immediately felt droplets of fuel hitting the back of my head and saw them whisking out the open canopy. I quickly put the airplane on the runway, and as it slowed down the fuel smell dissipated.
I taxied back to my hangar. As I turned the corner to my hangar row I looked back to see a trail of fluid along the taxiway. I shut down the engine and could hear gas dribbling out of the belly of the aircraft. I climbed out and found about half a gallon of gas was pooled beneath the rear seat. I wondered if I had somehow ruptured a fuel tank. Then I opened the fuel cap access panels to inspect the fuel caps and tanks. When I opened the port panel, everything was in order and the cap was on tight. When I opened the starboard panel I saw the culprit: the starboard cap was not fastened. The low pressure inside the wing had lifted the cap up and allowed fuel to siphon out of the tank, then flow into the center section before the vapors (and gas droplets) were drawn forward to the front of the cockpit. Apparently when the lineman had fueled the aircraft, he had placed the cap in its receptacle but had not locked it in place. About five gallons of fuel had been siphoned out of the tank.
I stared at the loose cap for a very, very long time and thought about how close I had come to a bad situation. I also thought about the National Transportation Safety Board report’s conclusion if it had been far worse: “Probable cause: The pilot’s inadequate preflight inspection….”
Since then I never let anyone else secure the fuel caps, and I always check them before every flight.
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