Excessive play in some brake parts was the probable cause of a runway accident involving airshow icon Patty Wagstaff and her V-Tail Bonanza at St. Augustine Airport in 2019. The final report on the mishap, which resulted in minor injuries for Wagstaff and her passenger, an instructor at her flight school based at St. Augustine, was released this week. The NTSB says the right brake of the Bonanza locked up on its own after Wagstaff touched it down and despite Wagstaff’s best efforts it left the runway, struck a berm and flipped. The plane was seriously damaged. At the time, Wagstaff tweeted that the incident was caused by a “mechanical issue” but didn’t elaborate.

The board said the wheel was spinning freely after the accident but they found play between the anchor bolts and their bushings in the torque plate. “Excessive caliper play can result in too much clearance between the brake pads and the brake disc,” the report said. “The excessive clearance can cause the brake pads to shift out of place and jam against the brake disc, which could result in an unintended brake application.”

Glad no one was hurt!

“The board said the wheel was spinning freely after the accident but they found play between the anchor bolts and their bushings in the torque plate. ‘Excessive caliper play can result in too much clearance between the brake pads and the brake disc,’ the report said. “The excessive clearance can cause the brake pads to shift out of place and jam against the brake disc, which could result in an unintended brake application.”

Uh, I don’t understand this. I’ve never worked on the brakes on a Bonanza. But if they’re like the standard Cleveland brakes that were on my Glasair, I don’t see how “too much clearance” could cause “unattended brake application.”

First, the only way that I can think of to have so much “excessive caliper play” that a brake pad assembly could fall off its guide is if a brakes pad was worn down to the metal of the brake pad holder. In which case a) the brake rivets would have eaten into the brake disc for a while, which, b) wasn’t caught on a pre-flight inspection, and c) the brake pedal would have felt horrible during taxi and the brake would have been ineffective. Not to mention the rattling noise while taxiing, and the horrible grinding noise when brake was applied, both which can be heard when wearing ANR’s.

And second, even if there was excessive caliper play (again, not found during pre-flight?), I don’t understand how that can cause a brake to apply. Even if I had forgotten to rivet a new pad to the pad holder on my brakes, I don’t see how my brake would jam. (I would likely blow the puck out.) And who’s doing the maintenance on this plane that the brake could have been worn this bad?

Can anyone here who’s worked on Bonanza brakes explain how a loose caliber could exert force on a brake disc to cause braking action? The link in the article didn’t take me to the report.

I had a brake puck jam once in a car, where the puck wouldn’t pull the pad back in. (Corrosion in the cylinder.) But that was in a car, with Hygroscopic brake fluid. And the Board didn’t say that a puck was stuck on Wagstaff’s plane.

Unless someone can explain this, it seems more likely that someone’s foot “stuck” on a brake pedal.

Wish the NTSB had identified the brake manufacturer. The aircraft is a 1958 model, so it’s quite possible they were Goodyears. I had one of the Goodyears on my experimental lock up, fortunately just while taxiing. Replaced them with Groves.

One issue with Goodyears is the scarcity/cost of replacement parts.

From the NTSB report, it appears that Ms. Wagstaff was in the left seat, and the aircraft was not equipped with brakes for the right-seat occupant. She had 300 hours in the make/model. By my lights, that’s probably enough experience to know how NOT to lock up a brake. Not definitive, of course…pilots make mistakes at any experience level.

But the Goodyear brakes on my experimental barely held the airplane when the mighty C-85 is at full roar. And why would the pilot be putting that much pressure on ONE brake, and not both?

I tend to go with the mechanical failure finding, here.

Thanks. I appreciate your insight. As I said, the link didn’t take me to the actual Report. The fact that there were no right side brakes eliminates one variable.

I’ve never heard of Goodyear brakes. But now I’m more confused. If the Goodyear brakes on your Experimental could barely hold, how is it that she couldn’t use opposite brake to keep the plane on the runway? But I suppose a failure might jam things. (Wouldn’t that show scoring in the disc?)

Well, I suppose we’ll never know what really happened. I’ve had leg spasms before, but they wouldn’t cause me to push (and hold) a rudder pedal. (Although my 84-year-old flying partner has bad leg cramps (from botched back surgery) which causes her to straighten her leg out to stop the pain.)

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