Aviation Accident Summaries

Aviation Accident Summary CHI02LA166

Urbana, IL, USA

Aircraft #1

N915D

Jacobs Rutan Vari Viggen

Analysis

The airplane was destroyed when it impacted terrain after a loss of control following a partial loss of engine power during the initial climb from the runway. A witness stated that the airplane had an unusually long takeoff roll, lifting off approximately 300 feet from the end of the 4,000 foot runway, and that once the airplane was airborne, the wings were "rocking and rolling". The pilot transmitted on the radio that he was having trouble climbing. The witness reported that the airplane entered a slow turn to the right with a high angle of attack. The witness stated that the airplane's nose fell to the right and the aircraft impacted the terrain nose first. A fuel leak was found around the accelerator pump housing on the carburetor. The engine was found to be running excessively rich when run on a test stand.

Factual Information

HISTORY OF FLIGHT On June 16, 2002, at 1030 central daylight time, an amateur-built Jacobs Rutan Vari Viggen, N915D, piloted by a commercial pilot was destroyed following impact with terrain on initial climb from runway 27 (4,000 feet by 57 feet, concrete), at the Frasca Field Airport (C16), Urbana, Illinois. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot was fatally injured. The flight was originating at the time of the accident and was en route to the Andy Barnhart Memorial Airport (3OH0), Carlisle, Ohio. A witness, who was familiar with the pilot and the airplane, observed the accident event from takeoff roll until it impacted the terrain. She reported that the takeoff roll was unusually long, noting that the airplane did not become airborne until approximately 300 feet from the end of the 4,000 foot runway. She reported that once airborne, the airplane's wings were "rocking and rolling" like the airplane was encountering turbulence, but not to the point of being out of control. The witness reported that she heard the pilot transmit that he was having trouble climbing. The witness reported the airplane started a slow, nose high turn to the right, and gained about 200 - 250 feet of altitude in the crosswind turn. She reported the airplane looked like it was in "slow motion" and that the "delta wing just kind of hung there." Approximately 7 - 8 seconds after initiating the turn, the airplane appeared to roll and the nose dropped to the right and impacted the terrain nose first. The witness reported that the airplane's landing gear was retracted in the turn. She reported the airplane appeared to stall/spin. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with single engine airplane, multi-engine airplane, and rotorcraft ratings. The pilot also held airplane and rotorcraft instrument ratings. The pilot held an experimental aircraft builders certificate. The pilot was issued a Second Class medical certificate on October 24, 2000 with "Must wear corrective lenses" printed in the limitations section. The pilot reported on his last medical certificate application, dated June 6, 2002, a total flight time of approximately 2,900 hours. The pilot accumulated approximately 250 hours in the accident aircraft. AIRCRAFT INFORMATION The accident aircraft was an amateur-built Jacobs Rutan Vari Viggen, serial number 100. The Vari Viggen is an experimental category airplane with a fixed delta wing and canard. The aircraft has two seats in a front and rear configuration. The accident aircraft was powered by a Lycoming O-320 series engine rated at 150 horsepower powering a wood pusher propeller. The accident aircraft was issued its registration certificate on July 19, 1983, and received its airworthiness certificate on December 13, 1994. The airplane accumulated a total time of approximately 250 hours prior to the accident. The last condition inspection was conducted by the pilot on December 11, 2001. The logbook entry by the pilot for that date states, "I hearby certify that this aircraft has been inspected as per FAR 43-17, Appen D and is in good operating condition." The last entry in the engine log was on November 21, 1998 by the pilot and stated, "...I certify that this engine has been inspected in accordance with a 100 hr [inspection] and determine to be airworthy at this time." METEOROLOGICAL INFORMATION The Automated Terminal Information Service at Willard Airport, Champaign, Illinois, located 9 nautical miles on a 190 degree heading from the accident site reported weather at 0953 central daylight time as: Winds: 360 degrees at 12 kts gusting to 17 kts Visibility: 10 sm Ceiling: Clear Temperature: 21 degrees Celsius Dew Point: 9 degrees Celsius Altimeter: 29.93 inches Mercury WRECKAGE AND IMPACT INFORMATION The aircraft was found resting on its canopy in a field, one nautical mile from the runway on approximately a 275 degree heading. Control continuity was established to all control surfaces. The reflex ailerons were found to be in the down position. The aircraft's reflex aileron position indicator fuse was absent. An on site examination of the engine revealed that the engine had remained on its mounts and firewall. The engine was rotated freely and completely with a clicking noise emanating from the left magneto. Spark was confirmed from all leads to the left and right magnetos. The engine had good thumb compression and suction on all cylinders. Continuity to all accessory gears was confirmed. The spark plugs were removed and found to be black and sooty. The carburetor was removed for further examination. The wooden propeller was found attached to the engine with both blades splintered. One blade was broken off near the hub and the other was broken off near the mid span. The spinner was in place with minor damage. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot at the Midstate Mortuary, Urbana, Illinois. The Federal Aviation Administration's Civil Aeromedical Institute prepared a Forensic Toxicology Fatal Accident Report on the pilot. The report indicated negative results for all tests conducted. TESTS AND RESEARCH The carburetor was inspected at RLB Accessories, Addison, Illinois. The float level was found to be properly set. The accelerator pump check valve initially stuck, but worked properly after being freed. A Federal Aviation Administration (FAA) Airworthiness Inspector conducted an engine test run at the Airframe & Powerplant (A&P) school facility at Lincoln Land Community College in Springfield, Illinois. The accident carburetor was reinstalled prior to the engine run. The inspection revealed the engine was running rich and would only take full throttle when the mixture was leaned back almost past half travel. The inspection revealed that the throttle response was "sluggish and the engine did not seem to develop full power." The accident carburetor was removed and replaced with a matching carburetor, MS-4SPA P/N 10-3678-32. The engine was then started with the exemplar carburetor mounted on the accident engine. The FAA inspector reported that the engine ran smoother and was not "puffing black smoke as it had on previous runs." He reported the engine "responded well to rapid throttle advances and the top RPM was noticeably higher than on previous runs." An inspection of the accident carburetor revealed "very little fuel was expelled when the throttle was pumped, and there was a noticeable leak around the accelerator pump shaft." The throttle arms on the accident carburetor and the exemplar carburetors were cycled from idle to full throttle. The accident carburetor had only a slight fuel flow from the carburetor throat while the exemplar carburetor exhibited strong fuel flow. (See Record of Investigation) ADDITIONAL INFORMATION The Federal Aviation Administration and Textron Lycoming were parties to this investigation. The aircraft wreckage was released to Mr. Ron Smith.

Probable Cause and Findings

The pilot's failure to abort the takeoff. Additional factors included the partial loss of engine power due to an excessively rich mixture as a result of a bad accelerator pump housing seal, and the pilot failed to maintain control of the airplane.

 

Source: NTSB Aviation Accident Database

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