CHI97LA221

A witness reported that after the airplane took off, he observed it in a steep climb, followed by a level off at about 100 ft agl. The airplane then entered a 90-degree turn to the left, followed by an erratic flight path with both wings rocking back and forth. It then went into a steep nose down, 45-degree right wing down attitude, before impacting terrain. An examination of the engine and flight controls did not reveal any preexisting failure or malfunction which would have resulted in the accident.

On July 23, 1997, at 1606 central daylight time (cdt), a Goble RV-4, N36JG, owned and operated by a airline transport rated pilot, was destroyed following initial climb after takeoff from a private airstrip when the airplane departed controlled flight. The airplane subsequently impacted a cornfield followed by a post-crash fire. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91 and was not operating on a flight plan. The pilot sustained fatal injuries. The flight departed Jensen Airstrip, Rosemount, Minnesota, at 1606 cdt.

According to an eyewitness, he observed the airplane takeoff was "...in a steep climb of at least 45-50(degrees)... ." The witness described the airplane to level off at approximately 100 above ground level (agl), and make a left 90 degree turn, followed by an erratic "waffled" of both wings back and forth. The airplane then went into a 45-degree nose down attitude with a right roll to 45 degrees. The witness said the airplane's engine sounded normal through out the 20 to 30 second flight. The airplane impacted terrain at a 75 degrees nose down position.

The owner of the grass airstrip stated that the pilot said about a week to ten days prior to the accident, that he had landed at his strip and complained of experiencing elevator flutter in a high speed descent (back side of the loop) at approximately an airspeed of 250 to 265 mph. The never exceed speed is 204 mph. The pilot and owner checked the exterior of the tail, specifically the trim tab and stabilizer, for any looseness, or other contributing problems to the flutter. No problems were found.

A post crash examination by a Federal Aviation Administration (FAA) Inspector, revealed a fractured elevator tube which was sent to the NTSB's Materials Laboratory Division for analysis. Flight control continuity was verified to all control surfaces. Engine continuity also revealed no pre-impact failures. Examination of the left horizontal stabilizer revealed defined bend marks in the skin on the corresponding edges of the left side stabilizer in a 45-degree angle. One of the eyewitnesses said that the marks were caused by the removal of the wreckage.

The elevator tube assembly was removed and send to the NTSB Materials Laboratory for examination. A copy of the report of the examination of the elevator tube is appended.

A post mortem examination of the pilot was conducted on July 25, 1997 at Regina Medical Center, Hasting, Minnesota. No pre-existent anomalies were noted during this examination.

The toxicological examination of post-accident specimens from the pilot detected 19.500 (ug/ml, ug/g) of Salicylate in the urine. According to the 1993 edition of the physicians' Deck Reference, Salicylate is any salt of Salicylic Acid, which is used in making aspirin, as a preservative and flavoring agent, and also in external treatment of certain skin conditions. According to a doctor at FAA's Civil Aeromedical Institute in Oklahoma City, Oklahoma, the reported amount of drug would not have had an effect on the pilot's performance during the flight.