AOPA has announced that its dual-fuel Beech Baron will remain in Oshkosh so mechanics can investigate stains discovered under the left wing during its display at AirVenture last week. The aircraft is being utilized as a test bed to compare the performance of General Aviation Modifications Inc.’s (GAMI’s) G100UL unleaded avgas with 100LL. The stains were found on the wing housing the tank containing G100UL, but it remains undetermined if they are fuel-related.
“We have scheduled a mechanic to determine the cause of the leak coming from the left wing of the Baron, which should happen in the next few days,” AOPA Senior VP for Media Kollin Stagnito told AVweb. “We are not yet sure what the substance is, nor where it is coming from.” Discussions regarding these stains have become a hot topic on various forums, sparking widespread speculation about their origin.
GAMI Chief Engineer George Braly suggested that a faulty or improperly installed fuel cell bladder or patch inside the bladder is likely responsible for the issue. He noted that some bladders in Barons might be over 40 years old and confirmed that G100UL had been tested for compatibility with bladder materials without any problems. Braly added that fuel bladder leaks are relatively common issues with Barons.