NTSB Factual Report

On October 16, 2003, about 1712 eastern daylight time, an Airbus Industrie A319-112, N764US, registered to and operated by U.S. Airways, Inc., as a Title 14 CFR Part 121 scheduled domestic passenger flight, from Tampa, Florida, to Pittsburgh, Pennsylvania, had the flight attendants injured while the aircraft was taxiing for takeoff at Tampa. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed. The pilot, copilot and 101 passengers were not injured. Two flight attendants received minor injuries and one flight attendant received serious injuries. The airplane was not damaged. The flight was originating at the time of the accident.

The Director of Flight Safety for U.S. Airways in the initial report of the accident, stated that the airplane was being taxied for takeoff at Tampa International Airport, Tampa, Florida, when the airplane's steering system failed, causing it to veer to the left. He further stated that the captain applied "abrupt" braking to prevent the airplane from departing the taxiway, and all three flight attendants, who were standing at the time, were injured, one of whom received serious injuries.

According to the captain, while taxiing to runway 36L, the airplane simultaneously lost steering, and he received two electronic centralized aircraft monitor (ECAM) messages related to steering, flight controls, and brakes. He said the airplane veered left, and he had to brake abruptly to avoid exiting the taxiway.

The first officer, stated that upon taxing out on taxiway W, north of W-2, he and the captain received ECAM messages for No. 2 brakes, nosewheel steering, and flight controls. He said he had just completed the flight control check, and was working on the before takeoff checklist, when the captain said that he lost nosewheel steering and brakes. He further said the airplane was headed off the taxiway, and that the brakes then became functional, and a "violent" stop occurred. He said that the ECAM messages went away after the nose wheel steering switch was moved from the off to on position, after which the airplane was returned to the gate. According to the first officer, had the captain not been able to stop the airplane, it would have departed the taxiway, and would most likely would have entered the ditch.

The NTSB examined the Cockpit Voice Recorder (CVR), and the examination revealed the presence of only conversations or other audio, consistent with maintenance personnel working in or near the cockpit. All possible pertinent information on the Cockpit Voice recorder was found to have been overwritten. The NTSB Cockpit Voice Recorder Factual report has been added as an attachment.

The NTSB examined the Flight Data Recorder (FDR), and the data revealed that electrical power was restored to the FDR at approximate Subframe Reference Number (SRN) 49246. At SRN 49303, N1 for the left engine began increasing while N1 for the right engine indicated holding at 20 percent. At SRN 49371, the parking brake was removed. At SRN 49382, the ground speed began to increase, the heading was changing, and N1 for both engines increased to 38 percent. At SRN 49449, N1 for the left engine began decreasing from 42 percent, and for the right engine from 39 percent. At SRN 49459, the ground speed indicated 30 knots on a heading of 180 degrees with N1 for both engines decreased to approximately 20 percent. One second later, the longitudinal acceleration indicated -0.44 g., the brake pedal position indicated 78 degrees and the brake pressure indicated 2,432 psi. At SRN 49468, the ground speed indicated 0 knots, and at SRN 49473, the parking brake was engaged. See the NTSB Flight Data Recorder Specialist's Factual Report.

US Airways maintenance personnel performed tests on the accident airplane's brakes and steering system and found that the Brake Steering Control Unit (BSCU) failed the cold reset test three times and the hot reset test twice. The report from maintenance personnel further states that the number one channel would fail and the number two channel would not pick up the load. During the course of maintenance efforts, the BSCU was replaced and all systems functioned functioning normally.

Messier-Bugatti, the manufacture of the BSCU, inspected and tested the effected BSCU, part number C2021633292C, serial number 5152, and according to their report, the BCDU was found not to be fully functional, and an internal failure associated with the first officers handwheel was found to exist.

NTSB Probable Cause

An intermittent fault with the airplane's Brake Steering Control Unit (BSCU) for undetermined reasons, which resulted in a momentary loss of brakes and steering, and a serious injury to a flight attendant during the resultant sudden stop during taxi for takeoff.