What happened
During a practice approach, the pilot extended the landing gear of the aircraft. The cockpit gear indicators showed only two green indications. Following this, a go-around was performed, and the crew cycled the landing gear several times in an attempt to achieve full extension. This included an attempt to utilize the emergency extension system, but the issue persisted.
After performing two confirmation passes, it was determined that the left main landing gear remained retracted while the nose and right main landing gear were extended. Upon touchdown on the right side of the runway, the aircraft exited the left side of the runway. There were no injuries reported in the incident.
The investigation
An examination of the aircraft revealed that the left gear extension push/pull tube was missing the lock pin in its clevis. While the pin was located in the belly of the aircraft, no nut or washer associated with the component was found. It was noted that the aircraft had recently completed maintenance work involving the landing gear system.