Find Fuel Leaks Using Your Cellphone

It’s a sight no builder or owner wants to see: the telltale stains on the bottom of the aircraft and the hangar floor that indicate a weeping fuel tank. The blue dye present in 100LL provides unmistakable evidence that fuel is escaping—but it doesn’t always help you pinpoint the source of a slow leak, due to the weird ways that liquid can migrate across a surface. Here’s an easy technique that can help you nail down exactly where leaking fuel originates from, using technology you probably already have in your pocket. Set up a bright light to illuminate the suspected area, secure your cellphone in a spot with a good view of the area—a small camera tripod is ideal, but anything that can hold a phone steady will work—wipe down the area to remove old fuel and stains, then hit Go on a time-lapse video recording. Leave it running for a few minutes, then review the results. Depending on how fast your leak progresses, you may have to try a few times to get the timing right, but eventually you should be able to catch it in the act. Through the magic of the time-lapse features supported by most modern cellphones, the camera can capture a fuel stain spreading out from its source, which is quickly apparent when you “scrub” the video forward and backward.

In this example, gaining access to the area of a slow fuel leak initially revealed an ugly blue mess, with no clear source. But after cleaning up the stains and shooting a few time-lapse videos, it was quickly apparent that the leak was emanating from one particular screw—probably as a result of a ground-wire terminal being added without doing a proper reseal job. Fortunately it’s an easy fix, and this airplane will be back flying in no time.

Now if only a builder could time-lapse their way through all the less-than-enjoyable parts of airplane building … we’ll be sure to look for that option when they roll out next year’s phones!