Event Details
During the final approach at an altitude of 30-50 feet, the first officer, who was pilot flying, brought both power levers to the flight idle position. The captain later reported hearing both engines transition into ground idle. The captain verified that both power levers were forward of the gate, then noted an increase in sink rate. The airplane subsequently bounced. After touchdown, the captain brought both power levers to the ground idle position, at which point the airplane veered to the right. The captain attempted to maintain runway centerline by applying asymmetric reverse thrust, but the airplane continued veering and departed the right side of the runway.
Touchdown and Ground Marks
The airplane touched down 484 feet from the approach end of the runway. Measurements of the distance between the first and second gouge marks on the runway, attributed to the right propeller, indicated that the ground speed at that point was 92 knots.
Aircraft Examination
Examination of the airplane revealed compression wrinkles on the lower wing skin at the wing splice location.
Engine Control Rigging Check
A rigging check of both engine controls found no evidence of improper rigging at the flight idle position. However, improper rigging was noted at the low and high reverse positions for the right engine.
Previous Discrepancies
Discrepancies pertaining to asymmetric reverse had been documented previously. There were no prior reports of high rates of descent when power levers were brought to the flight idle position.