G100UL unleaded fuel appears to damage aircraft paint under specific circumstances according to a California A and P who conducted his own compatibility tests on it and 100LL. Michael Luvara also said new nitrile O rings swelled beyond certified limits when submerged in the unleaded fuel for five to six days. GAMI recommends replacing nitrile components with those made of silicone or fluoropolymer elastomers.
Luvara produced the video above using time-lapse photography that appears to show softening and blistering of aircraft paint when the fuel is allowed to evaporate in place on the paint. GAMI has warned operators to wipe up any spilled fuel to avoid staining the paint on their aircraft but Luvara said his testing was designed to simulate a slight leak or a neglected spill. “It’s a complex situation with lots of nuances,” Luvara told AVweb. He said 100LL did not appear to damage paint in any of his tests, nor did it affect O rings.
Luvara theorized that after the more volatile components of G100UL evaporated, they left behind constituents that seem to be hard on paint. He said 100LL evaporated more quickly and uniformly. He said his tests led him to decline using G100UL in his airplane. He said that while wiping up spills is a reasonable expectation for operators they may not notice small leaks or seepage before damage occurs. Luvara has filed a report with the FAA and notified GAMI of the results of his testing.
We received Luvara’s video late Monday and GAMI did not immediately respond to our request for comment. We will run those comments when we hear back.
