WPR21LA362

The pilot reported that, when he applied brakes during the landing roll, there was no pressure on the right brake pedal. The airplane veered left and ground looped, resulting in substantial damage. The pilot reported that he observed hydraulic fluid on the right main landing gear after the accident. The accident was not reported until several months later. An examination of the parts retained by the pilot’s mechanic, including the brake, brake disc, and fittings did not reveal any preimpact mechanical anomalies or failures that would have precluded normal operation. The hydraulic fluid observed on the landing gear suggests the brake failure may have resulted from a leak at either the hydraulic line or the hydraulic inlet fitting to the brake; however, these items were discarded or replaced before the event was reported and could not be examined. The cause of the leak and right brake failure could not be determined due to a lack of available evidence.

On March 28, 2021, about 1200 Pacific daylight time, a Maule MX-7-235, N235X, was substantially damaged when it was involved in an accident near Ontario, Oregon. The private pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the pilot, he pressed the left and right toe brakes to decelerate the airplane during landing roll following an uneventful touchdown. The left brake pedal functioned normally, while the right brake pedal provided no resistance and depressed to the floor. The airplane immediately veered to the left, the right wing contacted the ground, and the airplane ground looped. After the pilot exited the airplane, he observed hydraulic fluid on the right main landing gear wheel. The ground loop was not reported to the NTSB until about 6 months after the accident. Photos provided by the accident pilot revealed substantial damage to the right aileron and elevator. The pilot reported that he was ferrying the airplane from Utah to his home after purchasing it when the accident occurred. One month before the accident, he told the owner that the right brake pedal on the pilot’s side didn’t work. He reported that the pedal movement was similar to what occurred during the accident. The owner informed the pilot that he would have his mechanic look at it; however, when the pilot arrived the day before the accident to take the airplane, he discovered that the brake issue had not been resolved. The owner’s mechanic then bled the brake, which seemed to resolve the issue at the time. The pilot then flew for 2 hours that day and did not experience any anomalies or failures with the brake system when he landed. He stated that he taxied the airplane the length of the runway twice and brought the airplane to a full stop to test the brakes before departing on the accident flight and noted that each pedal had equal pressure. The airplane’s brake system comprised both master and slave cylinders at the pilot and front seat passenger’s rudder pedal positions, connected to brake lines that feed into the brake through the hydraulic inlet port. The system is actuated by hydraulic pressure that extends the brake piston at the brake. This applies pressure to the brake disc on the wheel, which slows the airplane. The last annual inspection was completed 8 months before the accident. An examination of the brake system did not reveal any preimpact mechanical anomalies with the retained parts. The examination did not include the original inlet fitting from the accident airplane or hydraulic brake lines, as those parts had been discarded by the mechanic before the accident was reported. The original master and slave cylinders were not replaced but were successfully tested by the mechanic after new brake system components were installed.