This document provides information on contamination and its effects on brakes having carbon-carbon composite friction materials (carbon). Carbon is hygroscopic and porous, and therefore readily absorbs liquids and contaminants. Some of the contaminants can impact intended performance of the brake. This document is intended to raise awareness of the effects of carbon brake contamination and provide information on industry practices for its prevention. Although not addressed in this report, contaminants can cause problems with other landing system components including tires.
This document is intended to raise awareness of the effects of carbon brake contamination and provide recommendation for its prevention.
Rev A: Although carbon brakes had been operating for many years with only the occasional oxidation issue, the introduction of a new family of “environmentally-friendly” runway deicers in the early 1990s has resulted in dramatic increases in the occurrences and severity of carbon brake disk degradation due to catalytic oxidation. This revision contains additional information regarding the mechanism of oxidation, the role of these chemicals in promoting catalytic oxidation, and inspection techniques both on and off the aircraft.