Incident Overview
On May 23, 2013, at approximately 1200 central daylight time, a Stinson 108-3, registration N121CM, sustained substantial damage during a forced landing near Beaumont, Texas. The airplane nosed over after the pilot attempted to land in a field following a loss of engine power. The pilot received minor injuries.
Aircraft and Flight Details
The aircraft was registered to and operated by Aircapital Nevada, Inc., under 14 Code of Federal Regulations Part 91 as a business flight. The flight originated from Beaumont Municipal Airport, Beaumont, Texas, and was destined for College Station, Texas. Visual meteorological conditions prevailed, and the flight was not operated on a flight plan.
Pilot Report
The pilot reported that the pre-takeoff run-up indicated normal engine performance. After takeoff, the pilot made two 90-degree turns before experiencing a loss of engine power. The pilot noted that the engine continued producing some power but insufficient to maintain altitude. He selected a field for landing, during which the airplane nosed over.
Post-Accident Examination
Examination of the engine revealed compression on all cylinders, valve system continuity, and magneto operation. The carburetor appeared new, and the fuel strainer was clean with no debris. The fuel in the gascolator showed no visible water or sediment. The upper spark plugs had three different electrode configurations and exhibited a wet-black appearance. The rubber boot between the carburetor heat box and the cowl was pliable with external cracks. The rear of the boot was attached to the carburetor heat box with a clamp and sealant, but the front of the boot lacked a clamp; no clamp was found in the wreckage.
Expert Input
A member of the International Stinson Club (ISC) indicated that the front of the boot should have had a 2-piece clamp installed. Without the clamp, the boot could be drawn into the carburetor heat box inlet, potentially restricting airflow, resulting in a rich mixture and reduced engine power.
Damage
The airplane sustained substantial damage to the vertical tail surfaces, wings, wing struts, and fuselage.