Well THERE'S Your Problem!

Worn aluminum brake line

Our little single seater recently developed a ned to have its right brake bled--like after every few flights. We didn't let that go on more than twice before investigating. I was suspecting a leak in the bleeder valve--perhaps a piece of grit or gunk (we live in the desert after all), and a with a good disassembly and cleaning, I expected all to be well. After removing the wheel pant and noting the mass of glop surrounding the assembly, it was obvious that a good cleaning was in order, so scrubbing began. It was only after removing the gear leg fairing to expose more of the assembly that I noted a drop of red fluid on the low point of the soft aluminum tube (Versatube 3003). There was no way that was coming from the bleeder!

I wiped off the red drop - and another one appeared. Methinks I have found the leak! Well, at least its general location. More cleaning, and voilà - there was a little seep. A pinhole, located in an area that had been worn down by none other than the bottom of the fiberglass gear leg fairing. Ahhh, I hear you say - shouldn't that have been anticipated, and the potential for wear (yes, fiberglass cuts into aluminum - quite readily, thanks you!) mitigated? Yes, of course - and that had been done with a split piece of hose and some cable ties. But looking closely, the fairing edge had cut through that before getting to the aluminum tube!

The problem was one of gunk build-up hiding the problem, and frankly, the problem being missed by the mechanic (me) and inspector (also me). There is always more to be learned in this business!

New line, padded edges on the fairing, more tubing protection, and a new item on the condition inspection checklist--all done, and ready for the next time around. Oh - and the opposite side gear inspected and cleared for flight.

Paul Dye

Paul Dye, Kitplanes® Editor in Chief, retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the space shuttle. An avid homebuilder, he began flying and working on airplanes as a teen, and has experience with a wide range of construction techniques and materials. He flies an RV-8 that he built, an RV-3 that he built with his pilot wife, as well as a Dream Tundra they completed. Currently, they are building a Xenos motorglider. A commercially licensed pilot, he has logged over 5000 hours in many different types of aircraft and is an A&P, EAA Tech Counselor, and Flight Advisor, as well as a member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.

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