What happened
The pilot was operating the aircraft when ice began to accumulate on the wings. To address this, the pilot activated the airplane's deicing boots. However, the system failed to completely clear the right wing; specifically, the outboard three-foot section remained covered in ice. Approximately four inches of ice were later observed on the outboard leading edge of the right wing by ground personnel.
Due to the situation, the pilot decided to divert to a nearby airport. Upon arrival, an Instrument Landing System (ILS) approach was executed. During the final phase of the landing, the pilot reduced power early while in the flare. This premature reduction of thrust resulted in the airplane making a hard landing upon touchdown.
The investigation
Ground personnel examined the aircraft after the incident and observed about four inches of ice on the outboard leading edge of the right wing. This confirmed that the deicing boots did not fully clear the specified section during operation.