What happened
On June 3, 2011, an Embraer EMB-145, registration N607AE, was landing on runway 22R at Chicago O'Hare International Airport (ORD) when the No. 3 brake overheated and components separated. The flight, operated by American Eagle Airlines as flight 4176, arrived from Port Columbus International Airport under visual meteorological conditions.
During the landing roll, the flight crew felt one brake pedal release and then reapply. An air traffic control tower controller observed a puff of smoke during the rollout and inquired if a tire had blown. As the aircraft taxied on taxiway H, braking action decreased. The crew stopped the aircraft on the 32R pad for inspection, where they discovered the emergency brake could not hold the aircraft stationary. The crew also received hydraulic system failure messages and observed hydraulic fluid on the tires and the ground. There were no injuries among the 2 pilots, 1 flight attendant, or 49 passengers.
The investigation
Maintenance personnel inspected the brakes and identified a failure of the pressure plate and rotor. Pieces of the separated brake were recovered from runway 22R. An FAA inspector examined the No. 3 brake and confirmed that parts had disintegrated and separated.
Flight data recorder analysis showed that during landing, the air-ground switch recorded a ground indication at 132 knots, followed by a brief air indication for two seconds before returning to a ground indication. During this period, brake pressure for the No. 1 and No. 3 systems increased to 1,426 and 1,534 psi, respectively.
Brakes from the incident aircraft and three other aircraft were examined at the Goodrich Aircraft Wheel and Brake Facility. The examination revealed that all inspected brakes contained varying levels of oxidation.
Interviews with various maintenance personnel revealed that mechanics were not using the specified plastic probing tool for detailed visual inspections (DVI). Some mechanics reported using a screwdriver or a fingernail, and some were unaware of the specific DVI requirement or the existence of the specialized tool. Following the investigation, the operator updated its maintenance work cards, provided the necessary plastic probes to its maintenance system, and implemented updated training for its technicians.