Accident Overview
On July 9, 2010, at approximately 1500 mountain daylight time, an Ercoupe 415D, registration N87349, sustained substantial damage when its nose landing gear collapsed during an off-airport forced landing near Whitehall, Montana. The certificated private pilot, who was also the owner, was operating the airplane under 14 Code of Federal Regulations Part 91 for a local personal flight that had departed Whitehall about 1430. Visual meteorological conditions prevailed, and no flight plan was filed. The pilot was not injured.
Sequence of Events
The pilot reported that he departed with all three fuel tanks full. While returning for landing, the engine lost power. He executed a forced landing in a field; during the landing roll, the nose gear collapsed, and the firewall sustained substantial damage due to impact forces.
Post-Accident Examination
A Federal Aviation Administration (FAA) inspector examined the airplane at the accident site. The gascolator was found full of fuel that had the smell of automotive fuel; the owner indicated in a written statement that the fuel was a combination of 100LL avgas and automotive fuel.
Subsequently, a Safety Board investigator and the FAA inspector examined the airframe and engine at a recovery yard. The top spark plugs were removed and found clean with no mechanical deformation. The electrodes were gray, corresponding to normal operation per the Champion Aviation Check-A-Plug AV-27 Chart.
A borescope inspection revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head, and no discoloration on internal components.
Investigators manually rotated the crankshaft with the propeller. The crankshaft rotated freely, and the valves moved approximately the same amount of lift. The gears in the accessory case turned freely, and thumb compression was obtained on all cylinders in firing order.
Both magnetos were manually rotated and produced spark at all posts.
The fuel system consists of two wing tanks and a fuselage header tank in front of the cockpit. Examination showed that the fuel screens contained small amounts of contaminants. The fuel selector valve was unobstructed, and the port opened and closed freely. The fuel system is vented through the header tank fuel cap; no obstructions were identified.
Oil was present in the valve covers. Oil was drained from the oil sump, and the screen examined; it contained small pieces of red material. No other evidence of this contaminant was identified during the inspection.
Investigators obtained continuity between the cockpit throttle, mixture, and carburetor heat controls to the carburetor and carburetor heat door. The carburetor was removed and disassembled. The bowl was full of fuel, the vent was free from obstruction, the metal floats were intact, and the needle moved freely. Examination of the induction system showed no blockage.
Meteorological Conditions
According to a chart in Special Airworthiness Information Bulletin (SAIB) CE-09-35, the meteorological conditions at the time fell outside the range of probability for carburetor icing.