The private pilot stated that, during the landing roll, the right brake of the experimental amateur-built airplane failed. The Velocity SUV subsequently departed the runway at the airport in Puyallup, Washington, and hit an airport fence, resulting in substantial damage.
The airplane was equipped with a castering nosewheel and steering was accomplished through differential brake pressure. The pilot did not have any other means to either stop the airplane or maintain directional control once it had slowed to a speed below which rudder authority was available.
Postaccident examination revealed that the right brake disc had detached from the wheel hub. None of its attachment bolts were found, and the attachment bolts on the left brake disc were loose.
The bolts and discs had holes to accommodate safety wires, but no safety wires were found on either assembly.
The pilot had recently purchased the airplane following the completion of a condition inspection. Before the inspection, the airplane’s builder had adjusted the landing gear, which necessitated removal of the brake discs.
The builder could not recall using safety wires to secure the brake discs during the reinstallation, and the mechanic who performed the subsequent inspection also could not recall if safety wires were used.
Probable cause: The airplane builder’s failure to install safety wires on the brake disc attachment bolts, and the mechanic’s failure to identify the omission during the condition inspection. The subsequent brake disc separation resulted in a loss of directional control during the landing roll.
NTSB Identification: WPR17LA114
This May 2017 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Sounds to me like the builder was in a hurry to slap this thing together to get rid of it. As well, he found a shoddy mechanic to just give this thing a stamp of approval. I’m sure the builder wanted top bucks for the aircraft and the inspector wanted the big bucks for his “inspection”! This is a situation where the insurance company should refuse to pay out. Buyer beware as your life is on the line.
The builder used the wrong hardware to mount the brake disc. Matco specifies using 3 button head screws and 3 Nordloc , special locking washers parts. Hex head screws are the wrong part and there was no mention of the washers used.
The NTSB didn’t bother to check the Matco Assembly manual, which took me 1 minute to find online.
A hexhead screw may have worked if the Nordloc washers would have been used as well.
So the proper title should have been ‘Wrong Hardware Causes Brake Failure’.