My airplane has wingtip-mounted fuel tanks, installed under a supplemental type certificate (STC). In many ways, they’ve transformed and improved the machine by adding greater loading flexibility, thanks in part to a gross-weight increase. What drag they produce isn’t noticeable, and the additional endurance means the airplane is faster over some trips than it was before. For many of my destinations, I can depart with full tanks, fly to my destination, shoot an approach, miss it and fly home with reserves.
But the first time I flew the airplane after the installation was complete and signed off, I did slow flight and stalls to determine if the airplane’s low-speed characteristics had changed. After leak checks, I topped all the tanks and took off solo, heading for the practice area. I climbed to 3000 feet, cleared the area and flew level turns with the stall warner on for about five minutes. Then I pulled the power off and kept easing back on the yoke until the stall broke and the airplane fell off on a wing. I recovered, did one with some power and went home. My brief career as a test pilot was over. With the tip tanks installed, the airplane basically handled as it did before, and I was satisfied. But it just as easily could have gone pear shaped. I was, quite literally, the first to fly what was essentially an untested airplane.
