What happened
During the approach phase of flight, the first officer suggested performing a maneuver to remove ice from the wings. The captain declined, stating the intention to address any ice accumulation on the ground at the hangar. As the aircraft crossed the threshold, the first officer reduced power, which caused the sink rate to increase to 900 feet per minute.
Despite the application of back pressure on the yoke by the first officer and subsequent additional pressure by the captain, the high sink rate could not be arrested. The stall horn sounded during the descent, after which the captain took control. The resulting hard landing caused the right main landing gear to break, a fuel tank to rupture, and the rear spar of the right wing to bend upward. There were no injuries reported.
The investigation
Approximately 18 hours after the accident, investigators observed 3/16 inch of rime mixed with clear ice on the leading edges of the wing, the horizontal stabilizer, and the vertical stabilizer. This ice featured finger-like protrusions positioned vertically to the wing surfaces.
Review of company records revealed that the airline's line operations manual contained no discussion regarding specific flight characteristics or landing techniques related to wing ice. Additionally, it was determined that neither pilot had received the company's current Crew Resource Management (CRM) training.