On July 9, 2010, about 1500 mountain daylight time, an Ercoupe 415D, N87349, had the nose landing gear collapse during an off airport forced landing near Whitehall, Montana. The pilot/owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certificated private pilot was not injured. The airplane sustained substantial damage by impact forces. The local personal flight departed Whitehall about 1430. Visual meteorological conditions prevailed, and no flight plan had been filed.
The pilot reported that he departed with all three tanks full. He was returning for landing when the engine lost power. He made a forced landing in a field; the nose gear collapsed, and the firewall sustained substantial damage.
A Federal Aviation Administration (FAA) inspector examined the airplane at the accident site. The gascolator was full of fuel, and it smelled like automotive fuel (the owner indicated in a written statement that the fuel was a combination of 100LL avgas and automotive fuel).
A Safety Board investigator and the FAA inspector examined the airframe and engine at a recovery yard. They removed the top spark plugs; all plugs were clean with no mechanical deformation. The electrodes were gray, which corresponded to normal operation according to 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 they obtained thumb compression on all cylinders in firing order.
Investigators manually rotated the magnetos, and both magnetos produced spark at all posts.
The fuel system consists of two wing tanks and a fuselage header tank in front of the cockpit. Examination revealed 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 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.
The investigators obtained continuity between the cockpit throttle, mixture, and carburetor heat controls to the carburetor and carburetor heat door. They removed and disassembled the carburetor. 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.
The meteorological conditions fell outside the range of probability for carburetor icing according to a chart in Special Airworthiness Information Bulletin (SAIB) CE-09-35.