What happened
During a postflight inspection at William B. Hartsfield Atlanta International Airport, the first officer of a preceding AirTran Airways flight noticed a leak in the right engine of a Boeing 737-200. Maintenance personnel at the airport identified a chafed hydraulic pressure line related to the right thrust reverser as the source. Following a consultation with a maintenance controller in Orlando, the mechanics were instructed to cap the leaking line and deactivate the right thrust reverser per the airline's Minimum Equipment List.
Instead of capping the intended pressure line, the mechanics incorrectly capped the hydraulic pump case drain return line. A subsequent leak check using the auxiliary power unit and electric pumps failed to reveal the error. The mistake remained undetected until the aircraft entered its climb phase, at which point the overpressurized line caused the hydraulic pump case seal to rupture. This led to the depletion of hydraulic system A fluid.
As the aircraft returned to Atlanta, the crew declared an emergency. The loss of system A fluid disabled several critical components, including the nosewheel steering, ground spoilers, inboard flight spoilers, and both inboard brakes. Although the crew managed to land the aircraft using the rudder, the left thrust reverser, and the outboard brakes, the high landing speed and heavy weight caused the right outboard brake to fail due to friction material depletion. This failure led to a hydraulic leak in system B, subsequently disabling the left outboard brake. Without steering or braking, the aircraft veered off the left side of the runway and ended up in a ditch. There were 0 fatalities.
Findings
- Maintenance personnel incorrectly identified and capped the hydraulic pump case drain return line instead of the chafed pressure line.
- The failure to perform an engine-running test prevented the mechanics from detecting the overpressurization of the hydraulic pump.
- Maintenance staff lacked specific experience with the Boeing 737-200 due to recent company merger transitions.
- The use of the rudder to maintain directional control during landing depleted the system A accumulator pressure, preventing the use of emergency brake applications.