20130722013829A

The flight began at santa rosa CA with the intention of ending in seattle WA. Independence airport (7S5) was a planned refueling point. The pilot reports that he departed santa rosa with 50 gallons of fuel onboard 15 in each main and 10 in each tip. He planned an estimated burn rate of 10.5 gallons per hour for the 3.5-hour leg using 36.75 gallons.

Pilot claims he had the destination airport (7S5) in site while in cruise flight, at an altitude of 8500?. He began the descent and the engine experienced an unknown loss of power and went to an idle. Once the power loss was recognized the pilot states that he moved the throttle and turned on the boost pump yet the engine did not respond.

At an altitude of 1500?, the pilot reports that he performed his pre-landing checks and turned all fuel boost and transfer pumps on. At an altitude of 800?, he made no further attempts to re-store power to the aircraft and focused on flying the airplane.

The aircraft made a forced landing into a farm field 5.3 miles directly south of 7S5 runway 34. The first contact with terrain occurred in a field of corn with 5 to 6 foot tall stalks and then into a field of un-harvested OAT crop where it came to rest mostly right side up, on its left wing tip with left hand float pontoon rolled under the fuselage.

An onsite investigation by FAA safety inspector lance johnson revealed that the aircraft had sustained major damage to the left side of the fuselage, common to the gear attach points, the left wing skin/structure at the mid span area. The cockpit was intact and no obvious irregularities noted except for the absence of the multifunction displays for the engine and navigation instruments. The pilot had apparently removed these after the accident for security reasons.

Flight and engine controls were checked for proper travel and continuity no defects noted. The propeller tips indicated that the engine was operating albeit at a low power setting at the final point of the crash sequence.

The left main fuel tank contained fuel, as did the left tip tank. With the aircraft resting in a position of left wing very low, an accurate quantity was not determined. The right wing fuel level also could not be determined but fuel did drain easily from the sump. Visually, the quality appeared good with no moisture, debris, OR odorous indicators. The fuel was clear-blue in color and had the aroma of avgas not auto gas. With aircraft battery power supplied, the boost and wing transfer pumps made audible indications of functioning but without instrumentation, their function and or pressures were not further validated.

An inspection of the engine compartment with only the top engine cowling removed; revealed no obvious defects, no signs of fuel or oil leakage, loose lines or fittings, and an overall good condition. By means of pulling the propeller thru in the direction of rotation indicated good compression on all but one cylinder that was possibly low. A proper cylinder compression differential test would need to be performed to confirm. No definitive reason for an engine power loss could be determined at the accident site.