Incident Overview
During approach to land, the pilot observed that the landing gear down light did not illuminate. A missed approach was executed. The pilot then discussed the problem via radio with a mechanic and attempted all emergency procedures to lower the nose gear, but without success.
Emergency Actions
To reduce fuel weight and facilitate maintenance, the pilot diverted to Mandan via Bismarck. After another failed attempt to extend the gear, the pilot and mechanic decided the aircraft should be landed on the sod with all gear up.
Landing
A full flap landing was performed with the engines cut prior to touchdown. The aircraft slid approximately 250 feet after contacting the ground.
Post-Landing Examination
Inspection of the aircraft revealed that the nose gear torque tube was buckled. Initially, it was considered that a cooling hose or heater tube may have interfered with and buckled the tube by obstructing the retraction rod. However, a more likely reason was determined to be operation of the aircraft on rough terrain.