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Brake Failure
From CP73, Page 6, October, 1992

Dear Mike:
     Several weeks ago, I had a right brake failure on landing. Please re-alert others as to the serious nature of a brake failure, and suggest they frequently inspect their brakes. Finally, I suggest there may be a problem with Silicone brake fluid (DOT 5 motor vehicle standard #116).
     In the last 2 months, I have flown around 200 hours, and the brakes had been working fine. (Yes, the brakes were inspected twice during this period). The takeoff at MEI, prior to the problem landing, the right brake was nearly gone. Previous flight, only I hour before, indicated no problem. I aborted the takeoff to bleed the brake. This seemed to fix the problem and I left with excellent brakes. However, two hours later I landed at RKW with NO right brake.
     Assuming I might still have a problem, I landed with the wind on the right side. This worked great down to about 30 knots when it was obvious the nose had to be lowered to stop (I should have cut the engine on landing!). The damage was minor (retract gear and a few scratches) but could have been very serious. For example, had I landed the other direction, I would have left the runway at a much higher speed and went into the trees. The pilot has little control of a Long-EZ without brakes. It's a very sobering, dangerous situation -- best avoided!
     I inspected the brakes after the accident, and found three confusing things. The calipers and pads had retracted about 1/4" from the disk. Why? The pads, disk and wheel pant were covered with silicone brake fluid. A leak (but small??) was found in the tube where it connected to the caliper. I believe the leak was initiated by 7 years of age and a "hot" landing several weeks before at a high altitude airport. Finally, there was a "gummy" gray deposit on the 0-rings within the tubing and elsewhere. This indicates stability/compatibility/moisture problem with Silicone Fluid. I have changed back to standard good old red aviation fluid. It’s thicker, lubricates better, works and leaks are apparent! I had changed to silicon fluid about three years ago after reading about it in a CP.
     Mike, I have over 1300 hours in Long-EZ's and I have never had as serious a problem as this. I spend more time inspecting/working on my airplane than flying it! For example, in the last 7 years, I have replaced both master cylinders, upgraded to 50-106 disks and completely dissembled, cleaned and inspected the brake system 3 times. Yet, it got me! I will be even more attentive to the brake system!

Tim Crawford"

Editor's note: We have used silicon brake fluid (Dot 5) in all RAF airplanes for many years, the main reason was aircraft red brake fluid is highly flammable, Dot 5 is not. This is the first problem we have had reported. Mike did replace the o-rings in his master cylinders about 6 months ago and found a "grey" deposit in each cylinder. This was cleaned out and the brakes have functioned perfectly ever since. Has anyone else seen any problems using Dot 5 silicone brake fluid?