WPR10LA432

The pilot reported that, after cruising for about 30 minutes, the engine suddenly lost all power. During the forced landing in an open field, the airplane impacted a fence and then the ground. An examination of the airplane revealed that the engine’s magneto switch had failed. The switch was original equipment in the airplane, which was manufactured 79 years prior to the accident. The pilot reported no known maintenance history or malfunction of the magneto switch prior to the accident.

On August 28, 2010, about 1320 Pacific daylight time, a Stinson JR.S, N12164, registered to a private individual and operated by the pilot, collided with obstacles during a forced landing near Lake Stevens, Washington. The airplane was substantially damaged during the impact sequence and the subsequent ground impact. The private pilot and one passenger were not injured; a second passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The 14 Code of Federal Regulations (CFR) Part 91 personal flight originated from Snohomish, Washington, about 1245. The pilot reported to the National Transportation Safety Board investigator that he was on a local area flight with family members. Upon departure, the airplane contained about 28 gallons of fuel. While cruising, the airplane's engine suddenly lost all power. The pilot stated that he attempted to restart the engine but was not successful. The propeller continued windmilling during the pilot's efforts at restarting the engine. The pilot made a forced landing in a nearby open field. During landing, the airplane collided with barbed wire and a fence. While decelerating in the field, additional objects were observed, and the pilot sharply turned the airplane. The left main landing gear separated from the airplane, and the outboard portion of the left wing impacted the ground and the wing spars were broken. The pilot subsequently informed the Safety Board investigator that an examination of the airplane revealed its magneto switch had failed. The switch was original equipment in the airplane, and it had no known maintenance history. The switch had likely been in the airplane since 1931, when the airplane was built. The switch had no known history of malfunction. The pilot opined that its internal contacts had just worn out.