Embraer EMB-145 Brake Separation at Chicago O'Hare (N607AE)

Incident Overview and Immediate Aftermath On June 3, 2011, at approximately 0605 central daylight time, an Embraer EMB-145, registration N607AE, operated by American Eagle Airlines as flight 4176, landed on runway 22R at Chicago O'Hare International Airport (ORD). During the landing rollout, the No. three brake overheated, resulting in the separation of brake components. The aircraft sustained no damage, and the two pilots, one flight attendant, and 49 passengers were uninjured. The flight, a scheduled domestic passenger service under 14 Code of Federal Regulations Part 121, originated from Port Columbus International Airport. Visual meteorological conditions prevailed, and the aircraft operated on an activated instrument flight rules flight plan. ## Operational Sequence and Initial Observations During the landing rollout and while transferring aircraft controls, the flight crew reported a sensation of one brake pedal being fully released and then reapplied. The aircraft cleared runway 22R, and air traffic control issued clearance to cross runway 9R and make a left turn onto taxiway H. The tower controller inquired about a potential tire blowout after observing a puff of smoke during the rollout. As the aircraft taxied, braking action diminished. The crew stopped on the 32R pad for inspection and discovered that the emergency brake would not hold the aircraft stationary. Caution messages appeared regarding brake degradation, including hydraulic system two failure and system two hydraulic pump failure. A flight attendant reported that passengers saw smoke on the right side of the aircraft. The crew started the auxiliary power unit, shut down both engines, and the captain observed hydraulic fluid on the tires and the ground. ## Maintenance Inspection and Component Recovery Airport rescue and fire fighting personnel inspected the main landing gear and decided to tow the aircraft to the gate. Passengers deplaned via stairs and were bused to the terminal. Operator maintenance personnel inspected the brakes and identified a pressure plate and rotor failure. Airport operations supervisors inspected the runway and recovered separated brake parts from runway 22R just south of the taxiway Uniform intersection. A Federal Aviation Administration (FAA) inspector examined the aircraft and the separated parts on-scene. Observations and images of the No. three brake, part number 2-1707, revealed that parts of it had disintegrated and separated. The operator quarantined and shipped the incident brake, separated parts, and the No. two brake to the brake manufacturer for detailed examinations. The No. two brake had been installed on the aircraft at approximately the same time as the incident brake. ## Flight Data Recorder Analysis The operator downloaded a data file from the flight data recorder (FDR) and sent it to the National Transportation Safety Board’s Vehicle Recorder Division for decoding. The FDR data indicated that during landing, the air-ground switch parameter first recorded a ground indication at 0603:58 at an indicated airspeed of 132 knots. The parameter then showed an additional air indication for two seconds before recording a ground indication again. At this time, the recorded brake pressure values for the No. one and three brake systems increased, reaching peak values of 1,426 and 1,534 psi, respectively, in less than 10 seconds. A maximum longitudinal deceleration value of -0.39 g’s was reached at 0604:10. The No. three brake pressure value then decreased to a nominal value and remained there for the remainder of the recording. ## Manufacturer Examination and Oxidation Findings The two brakes from the incident aircraft were shipped to the Goodrich Aircraft Wheel and Brake Facility near Troy, Ohio. Brakes from three additional occurrences were also collected and sent for examination: the No. three position brake from N724AE, the No. three position brake from N812AE, and the No. four position brake from N630AE. A representative from the brake manufacturer examined the brakes using a specified plastic probing tool and published procedures for a detailed visual inspection (DVI), which checks for oxidation. Two Goodrich brake inspection service bulletins (SB 1063 and SB 1064) were released in September 2008, followed by a brake inspection service letter (SL 2087) in April 2009. Using the visual inspection procedures and tool, the examination revealed that all brakes contained varying levels of oxidation development. ## Training and Procedural Compliance According to an operator’s safety representative, Goodrich provided training material to the operator’s training department for brake oxidation course development. The operator developed Brake Oxidation Training courses I0462 and I0462_11 in 2009. These courses were loaded into all airplane mechanics required training folders on June 24, 2009, and all mechanics were required to complete the web-based training within 30 days. Completion was electronically monitored by supervisors. The representative reported that visual brake inspection alone was never suggested, and the training courses derived from Goodrich material stated that the use of a sharp plastic pick or a fingernail to check the carbon disk was the indicated method for oxidation detection. ## Mechanic Interviews and Facility Findings An FAA inspector assigned to the operator’s certificate management office conducted interviews with mechanics and inspectors involved with the five aircraft brake failures to verify procedures used during wheel removal and replacements. On June 21, 2011, the operator submitted a revision for a Main Landing Gear Wheel Assembly-Removal and Installation work card, incorporating details of the DVI requirement. On June 30, 2011, the operator received the first batch of brake inspection scribes specified in the detailed inspection. Interviews with mechanics at various facilities revealed inconsistencies in training and tool availability. A mechanic at the operator’s Dallas/Ft. Worth maintenance facility stated on June 27, 2011, that he did not visually inspect a brake on N630AE in accordance with the DVI, had not received training on the inspection, was unaware of the special tool, and the facility did not have the plastic probe. Similarly, a mechanic at the same facility stated on June 28, 2011, that he did not visually inspect a brake on N812AE in accordance with the DVI, had not received training, was unaware of the special tool, and the facility lacked the plastic probe. On July 28, 2011, a mechanic at the operator’s Raleigh/Durham International Airport maintenance facility stated that he did not remember visually inspecting a brake on N724AE in accordance with the DVI, had not received training, was unaware of the special tool, and used a screwdriver to inspect the brake. The facility did not have the plastic probe. On August 1, 2011, a mechanic at a contractor’s maintenance facility near Savoy, Illinois, stated that he thought he visually inspected a brake on N607AE, had not received training, was unaware of the special tool, and used his fingernail to inspect the brake. The facility did not have the plastic probe. On August 2, 2011, a mechanic at a contractor’s maintenance facility near Erlanger, Kentucky, stated that he thought he visually inspected a brake on N607AE, had not received training, was unaware of the special tool, and used a hyperlink that he thought took him to the correct inspection but actually led to the general visual inspection. The facility did not have the plastic probe. ## Corrective Actions and Follow-Up Between July 6 and July 12, 2011, the operator and brake manufacturer conducted formal training of the DVI inspection at four of the operator’s main maintenance base locations. The operator added a computer-based training course incorporating the DVI into recurrent training for maintenance technicians. On August 12, 2011, the operator issued a revised Main Landing Gear Wheel Assembly-Removal and Installation work card that clarifies the DVI requirement. As a result of the brake separation incident, the training courses I0462 and I0462_11 were re-loaded for all mechanics in August 2011. Within 30 days, 3,089 airplane mechanics had completed the web-based training. The requirement for the use of a plastic pick or a fingernail during the brake inspection process did not change from the original courses. Plastic picks were bought for the operator’s entire maintenance system in late June 2011. The representative indicated that during new hires indoctrination training, time is set aside daily to allow employees to complete the required web-based training and document its completion.