Incident Details
During a preflight inspection, the first officer actuated the main oxygen supply valve located in the cockpit. Upon opening the valve, a loud hissing sound was audible. Almost immediately thereafter, the cockpit became engulfed in flames. The copilot managed to exit the airplane and sustained no injuries.
Damage
The fire melted the oxygen system pressure reducer-regulator assembly and burned a hole in the right forward side wall of the airplane. Additionally, the cabin interior suffered substantial damage before ramp personnel extinguished the flames.
Investigation Findings
A laboratory analysis of the oxygen system components revealed the presence of oil within a deposit found on the interior of the oxygen cylinder. No further causal factors were identified in the source material.