Pilot Debrief

CIRRUS DESIGN CORP SR22 near Gulf Shores, AL — 2022-06-15

Final reportERA22LA275
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Date
2022-06-15
Location
Gulf Shores, AL, USA
Airport
JKA
Aircraft
CIRRUS DESIGN CORP SR22
Registration
N432CD
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The improper maintenance of the brake system, which resulted in the brakes overheating and catching fire and subsequent substantial damage to the airplane.

NTSB narrative

The pilot reported that, about two months before the accident, the airplane’s brakes felt soft after landing. Maintenance personnel bled the brake system and returned the airplane to service. After picking up the airplane from maintenance, the pilot felt that the brakes were “dragging” during taxi; while subsequently bringing the airplane to a stop to contact the maintenance facility, the rudder/brake pedals “went to the floor.” The same maintenance facility replaced the piston O-rings and brake pads on both brake calipers. The pilot flew the airplane for about two months without issue until he returned the airplane to the maintenance facility for its annual inspection. During the annual inspection, which was completed the day before the accident, the maintenance facility replaced the brake pads on both calipers and bled the brake system. On the day of the accident (the first flight following the annual inspection), the pilot performed a preflight inspection and taxied the airplane to the runway. He initiated the takeoff and then realized that the airplane was not accelerating. He aborted the takeoff, exited the runway, and brought the airplane to a stop. When the pilot attempted to taxi back to the maintenance facility, he lost all braking effectiveness. The pilot shut down the engine and the airplane rolled to a stop. After seeing smoke coming from under the airplane, the pilot and his passenger egressed. The pilot was able to extinguish the right main landing gear fire with the onboard fire extinguisher, but was unable to put out the fire on the left main landing gear, and the airplane sustained substantial damage to the left side of the fuselage and the left wing. The airplane utilized a free-castering nosewheel that relied on aerodynamic forces and differential braking for directional control while taxiing. The airplane manufacturer advised that proper braking practices were critical to avoid potential damage to the brakes and that the most common cause of brake damage and/or failure was the creation of excessive heat through improper braking practices; however, review of recorded data did not indicate that the pilot used engine power settings during taxi that would have required excessive braking to slow or steer the airplane. Additionally, the airport was mostly flat and there was no appreciable downslope or upslope gradient that would have caused him to excessively use the brakes. The airplane was equipped with organic brake linings at the time of manufacture. The manufacturer had issued a service bulletin that allowed for an upgrade to metallic brake linings, which also required upgrade of the wheel and brake assemblies. Review of maintenance logs revealed no evidence that the accident airplane had been modified in accordance with this service bulletin, and examination of the brakes and wheel assemblies revealed a mixture of parts from both organic lining brake assemblies and metallic lining brake assemblies. There are major differences between how organic and metallic brake assemblies are designed, and the components of each system are not interchangeable. Examination of the accident airplane revealed that the installed brake linings were metallic, but the brake pistons were not equipped with the piston insulators used with metallic linings. The right brake housing shim was not made from the original equipment manufacturer’s insulative (phenolic) material and therefore did not provide the thermal insulation that the phenolic shim provided. Additionally, the installed brake discs did not meet thickness specifications for use with metallic linings. Based on the available information, maintenance personnel’s improper use of metallic linings in the brake assemblies without piston insulators, with improper brake housing insulative shim material, and with undersized brake discs, greatly increased the probability of overheating and likely resulted in the brake fire.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot should have conducted further maintenance after noticing brake issues.

NTSB coding

Evidence available

  • Photos
  • 21 docket documents
View NTSB final reportView NTSB docket

Docket documents21

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