On February 24, 2003, approximately 1516 Pacific standard time, a homebuilt Grubert KIS TRI-R TR-1 experimentally certificated aircraft, N23KS, registered to and being flown by a student pilot, accompanied by a pilot rated passenger, was destroyed during ground impact and a post-crash fire following a loss of control in flight while turning on a right downwind at Thun Field, Puyallup, Washington. Both occupants were fatally injured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was personal, was operated under 14CFR91, and had just departed Thun Field's runway 34 several minutes earlier.

A number of witnesses reported observing the aircraft/occupants at Thun Field prior to the aircraft's departure on the afternoon of the accident. One witness at the fixed base operator's facility reported seeing the aircraft arrive and drop off a passenger, then take on another passenger. A second witness reported observing the aircraft on the ramp with the owner/builder in the left seat and the passenger in the right. He reported watching the aircraft start up and noted that the engine started and then quit twice before the pilot got it running continuously. He then observed the aircraft taxi out but did not see the departure.

Two additional witnesses in a vehicle on the airport reported seeing three men removing seat cushions from the aircraft. As they drove past the aircraft a short time later they observed two people inside the aircraft and observed the aircraft's engine starting and quitting several times. Shortly thereafter, they watched the aircraft takeoff. Another witness reported seeing the pilot/owner and passenger enter the aircraft, start up and taxi out. The witness walked out onto the ramp to watch the aircraft depart on runway 34 and reported watching the aircraft make a shallow climb out. He further reported that approximately 800 feet above ground the aircraft banked right to an eastbound direction, leveled momentarily and then banked right again to a southbound heading. During the second turn the witness observed the aircraft enter a 360-degree roll to the right and remarked that it "...looked like he recovered momentarily and then stalled again and went into a vertical spin..." (refer to attached witness statements).

A number of witnesses around the ground impact site reported observing the aircraft during its descent. Six of these eight witnesses all reported seeing the aircraft descending in a spin or spiraling maneuver, and all the witnesses reported hearing the aircraft's engine performing unusually (refer to attached witness statements).


The 72 year old pilot possessed a student pilot certificate originally issued on 06/20/2000 and with an expiration date of 05/31/2002. He held a third class medical certificate issued on 05/22/2000 with the restriction that the holder "Must wear corrective lenses." The pilot's total flight experience as well as his total flight experience in the TR-1 aircraft was not known and he did not report any flight time at the time of his last medical examination. He weighed 210 pounds at the issuance of this medical certificate.

The 64 year old passenger possessed a commercial pilot certificate. He held a third class medical certificate issued on 07/24/2002 with the restriction that the holder "Must have available glasses for near vision. Miscellaneous restriction assigned. Valid for student pilot purposes only. Certificate not valid after July 31, 2003." The passenger reported a total of 350 hours of flight time at the time of his last medical examination. He weighed 226 pounds at the issuance of this medical certificate.


According to several individuals familiar with the pilot and aircraft, the pilot used automotive gas in the aircraft. A witness at the airport on the afternoon of the accident reported observing the pilot fuel the aircraft from containers on the ramp. The local FBO reported that they did not provide any fuel services for the aircraft. The aircraft was reported to have extended capacity fuel tanks of 15 gallons per wing.

FAA records indicated the aircraft was originally certificated with a Franklin 85 horsepower reciprocating engine. The engine installed at the time of the accident was a Lycoming O-290-D2 rated at 135 horsepower. Individuals familiar with the pilot and aircraft reported that the pilot had installed a Subaru engine sometime between the original Franklin and the Lycoming engine. No aircraft or engine logs were found.

Weight and balance information was obtained from records held by Avstar, Inc. at Thun Field, Puyallup, Washington. The documentation showed that the aircraft was weighed on July 8, 2002, and the (new) basic empty weight was 943 pounds. The aircraft's certificated maximum gross takeoff weight was 1500 pounds. The aircraft was equipped with dual controls to all three control surfaces.


Thun Field is located at 47 degrees 06.24 minutes north latitude and 122 degrees 17.23 minutes west longitude and approximately 6,500 feet and bearing 200 degrees magnetic from the accident site. The airport is equipped with a single runway, 16/34 measuring 3,650 feet in length. A north traffic flow was in effect at the time of the accident and the airport has a left hand traffic pattern.


The aviation surface weather observation taken at McChord Air Force Base (TCM) at 1455 reported the following conditions:

A few clouds at 25,000 feet, 7 miles (statute) visibility, temperature +8 degrees Centigrade, dew point -9 degrees Centigrade, altimeter setting 30.07 inches of mercury, and winds from 340 degrees magnetic at 11 knots. TCM lies nine nautical miles bearing 255 degrees magnetic from the accident site.


The aircraft crashed in a residential area at a location bearing 023 degrees magnetic and 6,600 feet from the center of Thun Field. The latitude and longitude of the site was acquired via Global Positioning System (GPS) as 47 degrees 7.062 minutes North and 122 degrees 16.146 minutes West approximately 610 feet above mean sea level (refer to Chart I). The ground impact site was in the fenced off back yard of a private residence populated by about a dozen conifer trees about 75 feet in height (refer to panoramic photograph 1).

The aircraft's engine was observed embedded in the soil at the ground impact site in a nose low, right wing low attitude with its longitudinal axis (propeller end) oriented roughly northeast (refer to photograph 2). There was a spray of broken and fire damaged Plexiglas fragments and small parts distributed along a 175 degree magnetic bearing for a distance of approximately 65 feet from the ground impact site. The aircraft's left wingtip and aileron was observed a short distance west of this line near the base of two large trees. The wing spar was observed oriented along an approximate 070/250-degree bearing (refer to photographs 3 through 6). Virtually all of the aircraft with the exception of the engine had sustained extensive fire damage.

A number of horizontal branches of the encircling conifer trees were observed broken off, and numerous broken branches were observed lying on the ground on the northern edge of the ground impact site (refer to panoramic photograph 7 and photograph 8). A number of small branches observed at the ground impact site displayed angular to near perpendicular "cut" surfaces (refer to photograph 9). A small portion of one of the aircraft's elevators was observed entangled in the branches of a tree near the ground impact site. Both left and right elevator push/pull rods and associated bellcranks, where they attached to the elevator were found lying on the ground and were free of any significant fire damage. Both tube separation surfaces were approximately 45-degree fracture surfaces circumferentially at the tube separation point.

Control continuity from the cockpit rudder pedals to the rudder bellcrank was established. The elevator and aileron control surfaces were actuated by push/pull rods (aluminum tubing), most of which had been consumed in the post crash fire. The connecting bolts at the control surface ends and the control sticks within the cockpit were observed to be attached and the elevator trim tab cable was found continuous from the cockpit to the elevator tab end. Throttle, mixture and carburetor heat control cables were found to be continuous from the cockpit to the carburetor.

The propeller remained attached to the engine with one blade folded back around the engine through an arc of almost 90 degrees (refer to photograph 10). The opposing blade, which displayed a lesser degree of aftward deformation, also displayed extensive leading edge battering and a significant leading edge gouge more than one-half inch deep where the metal of the blade had been flattened aft perpendicular to the chordline (refer to photographs 11 and 12). The angle between the propeller axis and the engine drive shaft was measured and found to be displaced 41 degrees from the longitudinal axis (refer to photograph 13).


Roberto D. Ramoso, M.D., conducted post-mortem examination of the pilot and passenger at the facilities of the Pierce County Medical Examiner's Office, Tacoma, Washington, on February 25, 2003, (case number 03-055-0767).

The FAA's Toxicology Accident and Research Laboratory, Oklahoma City, Oklahoma conducted toxicological evaluation of samples from the pilot and passenger. The findings were reported as negative (refer to attached toxicology reports).


The aircraft's Lycoming engine and associated components were disassembled and examined at the facilities of Avstar, Inc., at Thun Field. The examination revealed no evidence of any pre-impact mechanical malfunction (refer to Attachment LYC-I).


On-site examination of the wreckage was conducted on February 25, 2003, after which the wreckage was verbally released to the property owner where the aircraft crashed. The engine was retained for further examination and subsequently released to a family relative on February 28, 2003. Written wreckage release was accomplished on June 24, 2003, and was documented on NTSB form 6120.15 (enclosed).

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