NTSB Factual Report

On October 3, 2009, at 1547 central daylight time, a Piper J3C-65, N70585, sustained substantial damage when it impacted terrain after a loss of engine power after takeoff from a grass airfield in Rosemount, Minnesota. The pilot received minor injuries and the front seat passenger received serious injuries. The 14 Code of Federal Regulations Part 91 personal flight was departing from Jensen Airfield, a private grass airstrip, on a local flight. Visual meteorological conditions prevailed and no flight plan was filed.

The pilot reported that there was a fly-in at the private airstrip and he decided to take a friend for a flight “around the patch.” After he preflighted the airplane, he started the engine and waited for about 10 minutes for the oil temperature to rise. He taxied out and did a run-up prior to departure. During takeoff, he added power slowly to full power, got the tail up, and slowly rotated. He reported that the airplane "felt slow." He tried to land, but he was too fast and there was “not enough room.” He pulled the carburetor heat on, but the engine lost partial power and the airplane “started to sink.” He banked to the left to avoid trees. He reported losing altitude, and then the airplane experienced a “stall spin to the left.” The airplane impacted a mature corn field. The pilot shut off the airplane’s magnetos and fuel, and exited the airplane with the passenger.

A Federal Aviation Administration airworthiness inspector examined the airplane. The inspection revealed that the magnetos and fuel selector were turned off. The fuel tank was ruptured. The primer was in and locked. The carburetor heat was out (on). The propeller was bent aft. The airplane was equipped with a seat belt and shoulder harness for the rear seat. The front seat was equipped with a seat belt, but no shoulder harness, although there was a hard attachment point for a shoulder harness. The flight controls exhibited cable continuity to the ailerons, elevator, and rudder.

The inspection of the 65-horsepower Continental A-65-8 engine revealed that the carburetor was broken in half, top to bottom. The carburetor air box was crushed from impact forces. The spark plugs were clean and clear. The left and right magnetos produced spark. The engine was rotated and it exhibited continuity in the drive train, and there was compression on all four cylinders.

At 1553, the observed weather at the Minneapolis-St Paul International Airport (MSP), located about 12 miles northwest of the accident site, was: Wind 320 degrees at 7 knots, visibility 10 miles, few clouds at 2,100 feet, broken ceiling at 3,400 feet, temperature 11 degrees Celsius (C), dew point 6 degrees C, altimeter 29.81 inches of Mercury.

The Transport Canada Carburetor Icing chart indicated that “Serious Icing – Any Power” conditions existed with a temperature of 11 degrees C and a temperature dew point of 6 degrees C.

NTSB Probable Cause

The pilot's delayed use of carburetor heat while operating in conditions conducive to carburetor icing.