As the ground was coming up at me I wished I was only hangar flying! I had taken off in my AX-7 with two friends one hour and fifteen minutes earlier. It was now 6:40 AM and the temperature was right at 72 degrees. We flew over the lake and woods to the west of town, skirting the new shopping center and staying well away from the populated areas. Our average altitude was about 2400 feet, since everyone in our club adheres to an unwritten altitude rule to avoid landowner problems.
Following the training my instructor had given me, I used up one of my two tanks almost to the point where the gauges no longer read. I switched to the other tank and we kept on flying. The weather was ideal and I had enough steerage to impress my passengers with my flying skills. Actually, I was feeling kind of impressed with myself, too.
About 15 minutes into the second tank, during a slight ascent, one of the passengers said she smelled propane. Neither her boyfriend or I could smell it, so I didn't worry. Five minutes later, I started smelling propane too. Without making a big deal out of it, I checked the first tank and then quietly leaned over with the pretense of picking up a glove and sniffed the top of the second tank. There was no odor from the tanks but when I stood up the smell was getting stronger. I decided that it might be a good idea to get closer to the ground. I let the balloon cool and slip into a 500 fpm fall.
A minute later, I started to hear hissing from somewhere around the bottom of the burners. I immediately shut down the second tank and switched back to the first. I did a few long blasts to slow down the descent which was up to 800 fpm by now. This worked. At 1000 feet, I hit the burner again and noticed with horror that it had that tinny, hollow sound indicating that I was running on fumes. I looked down over the side and could see that the site directly under us was pretty clear except for a small pumphouse and several trees. I turned on the burner full stop and continued to burn until the flame had shrunk back into the can. Since this system has only one hose per side and is only redundant because of the second burner and its tank, there was no backup. The pilot lights went out. I was down to about 650 fpm and the ground was coming up fast. My mouth was completely dry and my heart was pounding. I tried to remember what the Flight Manual said about emergency hard landings.
At that point I decided to risk using the other tank, reasoning that the buffeting of the air would clear away any excess propane vapor. I lighted the pilot lights and turned on everything I had. If I had had a Bic lighter on board I would have lighted it up too.
With every BTU I could muster, we slowed to 300 fpm. We were close enough to the ground to risk a bump so I shut off all of the fuel and told the passengers to hold on. The landing wasn't any worse than many I've made in the last six years and nobody was the worse for wear. At the repair station, we discovered a leak in the fuel line.
I learned a lot that day about redundancy and that using a tank down to exhaustion is a really stupid idea.