WPR12IA296

The pilot reported that when he started a right turn while taxiing for takeoff, the airplane’s right brake locked up and then both brakes became ineffective. The pilot was unable to stop the airplane, and it subsequently departed the taxiway, the nose landing gear collapsed, and the airplane came to rest nose-down in the grass. Data downloaded from the airplane’s multifunction display revealed that during the last 2 minutes of taxi, the airplane’s engine power setting varied between 1,450 and 1,530 rpm and that the airplane’s ground speed was about 20 knots. The pilot’s operating handbook states the maximum continuous engine power for taxiing is 1,000 rpm. Postaccident examination of the brake assemblies revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. It is likely that the pilot failed to maintain directional control because of the high taxi speed during the turn.

On June 17, 2012, about 1035 mountain standard time, a Cirrus Design SR20, N552PG, sustained minor damage when it exited the taxiway following a loss of directional control at the Deer Valley Airport (DVT) in Phoenix, Arizona. The private pilot, sole occupant of the airplane, was not injured. The airplane was registered to JEH Equipment Leasing L.L.C. and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed. The personal flight was originating at the time. According to the pilot, during taxi for takeoff, he started a right turn on the taxiway when his right brake locked up and failed. The airplane began to veer straight ahead and he was unable to stop the airplane prior to departing the taxiway due to the brakes being ineffective. The airplane sustained damage to its nose wheel assembly and engine propeller. Runway 7R/25L, which parallels the incident taxiway, has a 0.4 downhill slope in the direction the airplane taxied. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed no evidence of any preexisting mechanical anomalies with the left and right brake assemblies that would preclude normal operation. During repair of the airplane, the brake pads and tires were replaced and inspected by an authorized repair station and no abnormalities were noted with the exception of glazed brake liners. According to Cirrus Design Corporation Owner Service Advisory SA 05-04, excessive heat causes glazed linings. The airplane was equipped with an Avidyne avionics system which consisted of a multi-functional display (MFD). The data from the MFD was extracted by a FAA inspector and analyzed by the National Transportation Safety Board’s Vehicles Recorder Division. According to the recovered data, during the last two minutes of the taxi sequence, the airplane’s engine speed was between 1,450 to 1,530 rpm and the airplane reached ground speeds of about 20 knots. The Cirrus Design SR20 pilot’s operating handbook under Section 2 has a limitation that the maximum continuous engine speed for taxiing is 1,000 RPM on flat, smooth, hard surfaces. Power settings slightly above 1,000 rpm are permissible only to start motion for turf, soft surfaces, and on inclines. Use minimum power to maintain taxi speed. Under Section 10, Safety Information, the handbook states that the most common cause of brake damage and/or failure is the creation of excessive heat through improper brake practices. Pilots unaccustomed to free castering nose wheel steering may be inclined to “ride” the brakes to maintain constant taxi speeds or use the brakes excessively for steering. The handbook mentions to use only as much power (throttle) as is necessary to achieve forward movement. Any additional power added with the throttle will be absorbed in the brakes to maintain constant speed. This operating practice was stated again in Cirrus Design issued OwnerService Advisory SA 05-04.