Incident Overview
A cargo flight operating as JOS7216 from San José-Juan Santamaría Airport to Guatemala City encountered a serious hydraulic system issue shortly after departure. The aircraft, carrying two pilots and a load of various goods, departed runway 07 at 0940 local time. Upon reaching flight level 210, the crew declared an emergency and reported technical problems with the hydraulic system.
Flight Sequence
The crew received a 'HYDRAULIC QUANTITY' indication followed by a 'HYDRAULIC SYSTEM PRESSURE (L ONLY)' second indication. Subsequently, the left autopilot and yaw damper disengaged. Air traffic control cleared the flight to return to San José. The crew entered a holding pattern before initiating an approach.
Landing and Runway Excursion
The aircraft landed on runway 07 at a speed of 137 knots, compared to the reference landing speed (Vref) of 130 knots. After a normal touchdown, the crew began the braking procedure. The airplane then started to veer to the right. It skidded across the runway, executed an almost 90-degree turn, and descended a bank. The undercarriage was lost as the aircraft came to rest in a grassy area located approximately five meters below the runway elevation. The fuselage broke in two. Both pilots evacuated the aircraft with minor injuries.
Probable Cause
The official investigation determined that the airplane suffered a major failure of the left hydraulic system in flight. This failure rendered the autobrake, left thrust reverser, rudder ratio, and nosewheel steering system inoperative, and only a few spoilers remained operational. Contributing factors included fatigue and stress on the individual cables within the cross-section of the flexible hydraulic retraction hose of the left main landing gear down-locking actuator, as well as a probable inadvertent synchronized movement of the right reverse thrust lever and left engine control thrust lever, attributed to muscle memory.