TUCSON, AZ, USA
N81EZ
Parkman VARI-EZE
This was the maiden flight in the aircraft, and during construction, the pilot made numerous design modifications to the airplane which had changed the flight and performance characteristics. Instead of the airplane's engines recommended by the designer, the pilot had installed a GM Geo Metro automobile engine, which the pilot altered by the addition of a Mitsubishi turbocharger. The pilot also altered the fuel computer chip to adjust the fuel flow, attempting to achieve a 2-gallon-per-hour consumption rate. The pilot told associates that the engine produced 78 hp at 4,800 rpm. Engine technical data showed the actual power output of the unmodified engine to be 79 hp at 6,000 rpm. Severe detonation was found in the engine during postaccident examination and it is believed that it most likely would produce only 55 percent of rated power. Following takeoff, witnesses saw the aircraft in a nose high attitude and it never achieved more than 100 feet agl. Some witnesses said the nose attitude was as high as 15 to 20 degrees just before the crash. The pilot radioed that he was having a problem and said he had to put the aircraft down. The airplane collided with a tree during the attempted forced landing and a postcrash fire consumed the wreckage.
On December 18, 1998, at 0815 hours mountain standard time, an experimental Parkman Vari-Eze, N81EZ, collided with a mesquite tree during a forced landing attempt in the desert just east of Ryan Field, Tucson, Arizona. The aircraft, which was partially constructed and owned by the pilot, was destroyed during the impact sequence and subsequent postcrash fire. The pilot sustained fatal injuries. Visual meteorological conditions prevailed for the local flight, conducted under 14 CFR Part 91, which originated moments before the crash. The pilot had just departed Ryan Field for the maiden flight in the aircraft when he contacted the control tower and told them that he had a problem and that he "had to put it down here." Air traffic controllers who were interviewed after the accident stated that the aircraft did not appear to gain much altitude; only achieving about 100 feet of altitude above the terrain. Two ground witnesses who were driving on a nearby road said that the pilot had just cleared the departure end of the runway and had a 15- to 20-degree nose up attitude when it "looked like he was attempting to climb but couldn't get the power." They said that the engine was running and that they didn't notice any smoke or debris coming from the engine. They said that the airplane appeared to be in a slow, nose high attitude. An eyewitness who was piloting a Cessna 150 nearby said he heard the experimental aircraft advise the Ryan tower that he was having problems. He said that the tower controller cleared the aircraft to land on runway 24. He said that he heard the pilot advise the tower that he was only 100 feet above the ground. The controller said they tried to contact N81EZ, but with no success. They asked the pilot in the Cessna to fly to the area where they believed N81EZ had landed. The pilot in the Cessna advised the tower that he saw a possible metallic object engulfed in flames. Tucson Airport Authority Fire Department was notified at 0816 via dispatch of an Alert III at Ryan Airfield. PERSONNEL INFORMATION The pilot's personal logbook was never recovered in his personal effects, hangar, or through a diligent search by the family. According to Federal Aviation Administration (FAA) records, the pilot had accrued a total flight time of about 900 hours. Review of the FAA airman records disclosed that he held a private pilot certificate, with airplane ratings for single engine land. His most recent third-class medical certificate was issued on October 26, 1998, with a restriction that he must wear lenses for distant and possess glasses for near vision. AIRCRAFT INFORMATION The Vari-Eze is a high performance, day VFR, two person seating, custom-built aircraft. According to the Vari-Eze owner's manual, the Continental aircraft engine models A-75, A-80, C-75, C-85, C-90, and O-200 (75 through 100 horsepower) are currently approved for use on the Vari-Eze by the designer. The maximum allowable weight of the engine, propeller, propeller extension, exhaust and spinner is 240 pounds. The owner's manual stated that the maximum engine and accessory weight was 215 pounds. This was the maiden flight for the aircraft since the owner had completed his modifications to the aircraft. A local test pilot that also resides at Ryan Airfield told Safety Board investigators that the pilot of the accident aircraft approached him and asked him to test fly his Vari-Eze. The test pilot said he didn't like the workmanship on the airplane. He said he thought that the pilot had purchased the airplane partially assembled. He said that it was common knowledge that the pilot had been doing taxi tests on the airport property, and added that the pilot "had a reputation of having incidents on the airport." He said that he thought the pilot had modified the Vari-Eze from the specifications called for in the plans. WRECKAGE AND IMPACT INFORMATION The accident site is in the high desert near Tucson with an approximate elevation of 2,420 feet mean sea level (msl). The area is surrounded by scrub brush, rocky/sandy terrain, cactus of different varieties indicative of the area, and small desert mesquite and palo verde trees. The first identifiable contact occurred to a 12-foot-tall mesquite tree which had freshly broken branches at the top of the tree. A path of ground scars and debris was noted to extend from the tree on about a 170-degree magnetic bearing. The first ground impact point occurred about 124 feet from the mesquite tree. Portions of the red Plexiglas were located immediately after the initial ground scars. The nose wheel assembly departed the main wreckage, as well as the right wing and canard of the aircraft. The canard assembly was found just prior to where the main wreckage was located, which was surrounded by burned vegetation. The entire cockpit gauges, instruments, and controls were consumed in the postcrash fire. The main wreckage was located at 32 degrees 08.09 minutes north latitude by 111 degrees 07.57 minutes west longitude. The airport was located 2.15 nautical miles from the crash site. AIRCRAFT EXAMINATION No aircraft records of any kind were ever recovered to indicate the maintenance or component history. Extensive attempts to locate the maintenance records through the hangar, family, and business associates were made with no results. All maintenance history is purely antidotal; maintenance history was given to the Safety Board through two close associates of the pilot who were given party status. The aircraft, propeller, and engine were examined in Phoenix, Arizona, on February 3, 1999. According to the designer's representative, the canard which came off the fuselage during the impact sequence, had separated together with the attach bolts and aluminum bushings. The designer's representative stated that he "had never seen this occur before." Additional examination of the canard revealed that the builder had neglected to install the correct AN 970-4 wide area washers under the heads of the canard attach bolts. According to the designer's representative, this allowed the bolts and bushings to pull through the F22 bulkhead, leaving the bulkhead in place. The engine attached to the airframe was a 4 cylinder, all aluminum overhead cam automobile engine, which had been removed from a General Motors Geo Metro. This engine assembly was weighed complete with the engine mount, exhaust system, a small turbo-charger, and a reduction gearbox. The total weight was 206 pounds, which according to the owner's manual, is very close to the weight of the recommended Continental O-200, which is a 100-hp engine. The owner told friends that the engine produced 78 hp at 4,800 rpm; however, information obtained from the Chevrolet Geo Metro web page suggested that the power rating is 79 hp at 6,000 rpm. According to the designer's representative, this was a significant discrepancy, and could have led to an incorrect assumption being used to calculate the reduction drive ratio. According to one of the pilot's close business associates, the pilot told him that with the turbocharger installed, this engine had produced 120 hp. A teardown of the engine was performed on February 3, 1999, in Phoenix. The sparkplug for the No. 2 cylinder was found to be in operative due to the ground electrode on the plug had completely melted away. The top of the piston in the No. 1 cylinder had melting at the edges of the piston. The Nos. 3 and 4 cylinders appeared to have normal operating signatures. The No. 2 exhaust port exhibited a heavy coating of greenish deposits. According to the designer's representative, these deposits were consistent with unburned engine oil. All of the spark plug wires were burned and partially destroyed. The designer's representative estimated that the engine was not capable of producing more than 55 percent of its maximum power. The turbocharger, a Mitsubishi design of unknown origin, was disassembled and found dry. One oil line to the turbocharger was found plugged with debris. The impeller shaft and bearings were free to rotate, with metal spatter noted on the intake side of the compressor housing. The impeller blades exhibited a dark carbon-like deposit on the exhaust side of the turbocharger. The reduction drive was disassembled. The owner had designed and built an approximately 2:1 chain reduction drive system. This consisted of an approximately 2-inch diameter sprocket, driving an approximately 4-inch diameter sprocket via a 1.5-inch wide Hyvo chain. The drive shaft with the smaller sprocket was splined, and was driven directly by the engine through a matching female spline in the flywheel. The propeller drive shaft consisted of two 4130 steel tubes, one inside the other, with an outside diameter of only 1.125 inches, and a total wall thickness of about 0.25 inches. This tubular shaft was supported by two ball bearings, which were required to absorb radial loads as well as axial loads. Evidence of axial play was found in this shaft/bearing assembly. According to the designer's representative, the propeller thrust loads had caused the shaft to move forward in the reduction drive housing, to where the forward end of this shaft had been rubbing against the housing. The end of the shaft, as well as the inner race of the forward ball bearing, were blue. This, according to the designer's representative, was due to significant signs of friction generated heat distress. Further examination revealed that the larger sprocket had been secured to the propeller shaft by simply drilling a 3/8-inch diameter hole through both the sprocket hub and the propeller shaft. A case hardened steel dowel pin had been driven into this hole, passing through the sprocket hub and the propeller shaft. There were no safety devices retaining the pin into the hole. When the pin sheared at the outside diameter of the propeller shaft, the center portion of the pin remained in the tubular prop shaft, but the two loose ends of the pin slipped out of the sprocket hub and caused considerable damage to the interior of the reduction drive. Three access plate retention nuts were sheered or broken from their bolts and found lying in the gearbox casing. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed by the Pima County Forensic Science Center (FSC), with tissue and fluid samples retained for toxicological examination. The samples were submitted to the FAA Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. Separate toxicological studies were conducted by FSC. According to the Manager, Toxicology and Accident Research in Oklahoma City, the samples from the pilot were negative for alcohol and all screened drug substances. According to the second toxicological examination performed in Tucson, the sample from the pilot was negative for all screened drug substances. ADDITIONAL INFORMATION The Designated Engineering Representative (DER) who examined the aircraft was interviewed on December 21, 1998. He stated that the pilot had purchased the Vari-Eze earlier that year. He said that the pilot was in a partnership with another man and that they were modifying computer chips in vehicles through the carburetor injection system. He said that the pilot had attempted this in the Vari-Eze and that they were attempting to capitalize on the fuel control module. He stated that the pilot claimed he would be able to obtain a 2-gallon-per-hour burn rate using the computer chips fuel controls. The DER described the workmanship on the aircraft as "passable but rough." He said that the pilot was supposed to contact him if he had modified any system on the aircraft. Additional persons participating in this investigation are: Justin Mall Tucson, AZ John Eller Scottsdale FSDO The aircraft wreckage was released to the widow on February 13, 1999.
The pilot's failure to attain and maintain an adequate flying airspeed during the aircraft's maiden flight, which resulted in a stall/mush condition. Also causal was the pilot/builder's decision to modify the engine and the fuel system control microchip, which resulted in detonation and a severe reduction in power output, and led directly to the pilot's inability to attain and maintain airspeed.
Source: NTSB Aviation Accident Database
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