CHI96LA068

The pilot said that upon crossing the runway threshold and lowering 25 degrees of flaps, 'the airplane pitched down.' The pilot 'immediately released the flaps and added power, but the airplane was basically uncontrollable at this point.' The pilot reduced power and lowered the flaps prior to striking the runway. The airplane struck the runway on centerline and slid 1,000 feet before coming to a stop. Examination of the wreckage revealed heavy impact damage forward fuselage, engines and wings. Approximately one-half inch of rime ice was observed adhering to the leading edges of the left and right horizontal stabilizers, and along the leading edge of the vertical stabilizer.

On January 9, 1996, at 2312 central standard time (cst), a Piper PA-34-200T, N3679M, operated by a commercial pilot, sustained substantial damage when during final approach for landing, the airplane impacted on the runway. Visual meteorological conditions prevailed at the time of the accident. The positioning flight was being conducted under 14 CFR Part 91. No flight plan was on file. The pilot sustained serious injuries. The flight originated at Sioux Center, Iowa, at 2200 cst.

In his written statement, the pilot stated that he flew a normal ILS approach with 10 degrees of flaps extended. "When I broke out (of the clouds), I checked for ice with a flashlight. The windshield was free of ice. The left inboard wing was free of ice. On short final, I decided to stay fast and land with 25 degrees of flaps. Upon crossing the threshold (of the runway), I put on 25 degrees flaps and the airplane pitched down. I immediately released the flaps and added power, but the airplane was basically uncontrollable at this point." The pilot reduced the power and lowered the flaps prior to striking the runway. The airplane struck the runway on centerline and slid 1,000 feet before coming to a stop.

A witness who observed the airplane from the ground stated that, "at 100 feet above the ground, at what appeared to be sufficient approach speed under normal conditions," the airplane "lost pitch stability and went into an increasing pitch oscillation." These "big pitch changes" lasted approximately four seconds, after which the airplane struck the runway.

The Federal Aviation Administration (FAA) inspector who examined the wreckage at the site found heavy crush damage to the forward fuselage from the nose to just aft of the wing roots. Crush damage was also observed underneath both engine cowlings and the underside of both wings from the wing roots to just outboard of the engine cowlings. Both propellers were broken off at the hubs. All four propeller blades showed significant bending and tip curling. Six propeller strike marks, three corresponding to each engine, were observed on the runway. The oil pans from each engine had broken off. All three landing gear were sheared off. The aileron control cables were broken. Control continuity for the elevator and rudder was confirmed. Examination of the engine and engine controls revealed no anomalies. Continuity of the deicing system was confirmed. All other airplane systems were found to function normally.

Approximately one-half inch of rime ice was observed adhering to the leading edges of the left and right horizontal stabilizers, and along the leading edge of the vertical stabilizer.

The pilot received a weather briefing from Fort Dodge Flight Service Station prior to takeoff from Sioux Center, Iowa. The briefing contained an AIRMET for icing below 5,000 feet mean sea level (MSL), in the Des Moines, Iowa area.

The Des Moines International Airport's ATIS, at 2256 est, reported that a pilot in a Cessna 210 experienced light to mixed icing, eight miles northeast of the airport, between 2,500 and 3,700 feet MSL.