Event Description
The crew reported that the preflight examination, takeoff checks, takeoff roll, and rotation from runway 26 were normal. Once airborne, with the landing gear down and flaps at 20 degrees, the airplane began a roll to the right. The captain used differential thrust and rudder to prevent the airplane from rolling over. He observed that as airspeed increased, the roll tendency increased; as airspeed decreased, the roll decreased. The captain considered an asymmetrical flap misconfiguration. Both pilots stated that no lights or warnings illuminated. The airplane continued a right turn, bringing runway 13 into view. The captain completed a landing to the right of that runway, landing long and in the grass with a 9-knot left quartering tailwind. The airplane then paralleled the runway and struck an airport perimeter fence beyond the runway's end.
Cockpit Voice Recorder Analysis
The cockpit voice recorder revealed that the crew initially used challenge-and-reply checklists. After completing the takeoff checklist, engine power increased. About seven seconds after the first officer called "V1," the captain uttered an expletive, and the first officer announced "positive rate." During the next 50 seconds, the captain repeated numerous expletives, an automated voice issued multiple "bank angle" warnings, and the first officer asked what he could do. The captain later instructed him to declare an emergency. There were no calls by either pilot for an emergency checklist or callouts of emergency memory items.
Examination of the Right Roll Spoiler
Each wing incorporated four hydraulically actuated spoiler segments. The outboard segment, the roll control spoiler, normally extends with its aileron after the aileron has moved more than about 3 degrees, extending up to 50 degrees at full control wheel rotation. When the airplane was examined in a hangar, hydraulic power was applied via a ground unit, and the right roll spoiler elevated to 7.9 degrees above the flush wing level. Multiple left/right midrange turns of the yoke, with hydraulic power on and off, resulted in the roll spoiler extending normally but returning to a resting position of 7.8 to 7.9 degrees above flush. When the yoke was turned fully right and left, with aileron boost on or off, both wings' roll spoilers extended to full positions per specifications; however, after full deflection testing, the right roll spoiler returned to 6.1 degrees above flush. A final yoke turn resulted in 5.5 degrees elevation. The right wing roll spoiler actuator was examined at the manufacturer, and the roll spoiler was found to jam. The actuator was disassembled, but no specific reasons for the jamming were found. The roll spoiler parts were also examined with no indications of why the actuator may have jammed.
Emergency Procedures and Cockpit Switches
According to the flight manual, if any spoiler segment floats, moving the spoiler hold down switch to "Spoiler Hold Down" locks all spoiler panels down. The roll control spoilers may then be used in roll mode by turning on the auxiliary hydraulic pump. An "Aileron/Spoiler Disconnect" T-handle is available to release the tie between ailerons and roll control spoilers in event of a jam. When used, the pilot's yoke controls only ailerons, and the copilot's yoke controls only roll control spoilers. Although the jamming of the right spoiler initiated the event, proper application of emergency procedures should have negated the adverse effects. Memory items for an uncommanded roll include moving the spoiler hold-down switch to the "on" position, which was not done; the spoiler hold-down switch was found in the "off" position. The captain thought he may have had an asymmetrical flap configuration, but if an asymmetry had been the initiating event, the flap system would have been automatically disabled and flap segments mechanically locked. The aileron/spoiler disconnect T-handle was found pulled up; the crew indicated that this occurred when the first officer's shoe hit it during evacuation. While pulling the T-handle would have been appropriate for a different emergency procedure to release the tie between ailerons and roll control spoilers in event of a jam, it would have actually hindered control because it disconnected the left roll spoiler from the captain's yoke, making it more difficult to counter the displaced right roll spoiler. Although the crew indicated the T-handle was pulled during exit, its position, safety cover, and means of activation make this unlikely. Precertification testing showed that even with the right roll spoiler fully deployed, as long as the pilot had use of the left roll spoiler with that aileron, the airplane should have been easily controlled.