N224AM

On August 19, 1997, at 2221 central daylight time (cdt), a Swearingen SA226TC, N224AM, registered to Superior Aviation, Inc., was substantially damaged following a loss of control during the landing roll on runway 05 (6,501' x 150' asphalt), at the Des Moines International Airport, Des Moines, Iowa. The commercial pilot reported minor injuries. The 14 CFR Part 135 cargo flight was operating in instrument meteorological conditions. An IFR flight plan had been filed. The cargo flight departed from Wichita, Kansas, at 2050 cdt, with an intended destination of Des Moines, Iowa.

According to the pilot's written statement, he was on approach to land on runway 05, when it was observed that the right engine control was stuck at the maximum power position. The pilot indicated that it seemed like the right engine was disconnected from the right power lever. Upon breaking out of the clouds the pilot found himself approximately 1 1/2 miles from the runway and too high to make a safe landing so he chose to execute a missed approach. The pilot found the airplane would not maintain altitude with the gear down and one engine at zero thrust. Upon shooting a second localizer approach to runway 05, he found it hard to keep the airplane straight and level because of the power differential between the two engines. The pilot said, "Upon touchdown, within the first third of the runway, I attempted to engage Beta Mode on both engines. Only the left engine engaged while the right engine remained at full power. My intention was to keep the aircraft directionally controllable and stop the aircraft in the shortest distance possible. After touch down I realized directional control was minimal. I made a decision to go around rather than to risk running off the runway. I advanced the power on the left engine to MAX power and rotated. The aircraft then spun out of control and off the runway (end)." During a telephone interview, he stated that he had problems controlling the airplane on the runway so he advanced power on the left engine and initiated a go-around 1/2 way down the runway. The airplane became airborne, but settled back to the ground after reaching 130 knots.

According to the Federal Aviation Administration (FAA) approved Swearingen Metro SA226-TC Pilot's Operating Handbook, it states for a power plant control malfunction; "in the event there is an indication of improper operation of a fuel control or propeller control, it is recommended that the affected engine be shut down and a single engine landing accomplished."

An Air Traffic Control Tower controller who was working Local and Ground Control observed the airplane touchdown at a high rate of speed in the vicinity of Taxiway M (approximately 1/3 down the runway). The controller reported that as the airplane passed Taxiway Q (2/3 down the runway), it appeared to be having directional control problems. The controller observed the airplane to exit the end of the runway and skid sideways through the localizer antenna onto the grass area. The pilot also did not advise nor declare an emergency.

An FAA Inspector represented the NTSB during the on-scene investigation. The inspector observed tire marks which appeared to be skid marks from the end of the runway to where the airplane came to rest. During the investigation it was determined that the right engine power control cable housing was disconnected. This gives the cable no anchor point for the sheathing and it prevents the rod end from moving, but allows the sheathing to flop back and forth. This occurred due to a safety tab being broken off, allowing it to unscrew. The maintenance log books revealed maintenance was performed on the right engine on July 19, 1997. The discrepancy was on the right engine power lever being stiff. The mechanic re-rigged the engine power cable. All other flight and engine controls were inspected and were found to have continuity. Both engine propeller governors and fuel control units were removed and bench tested. The tests and inspections reveal no pre-accident anomalies with the units.