Accident
On October 17, 2015, about 0841 central daylight time, an experimental, amateur-built Vans RV-4 single-engine airplane, registration N999ZF, collided with terrain while maneuvering near Cortland, Nebraska. The private pilot and the pilot-rated passenger were fatally injured, and the airplane was destroyed. The flight was operated under 14 Code of Federal Regulations Part 91 without a flight plan. Day visual meteorological conditions prevailed at the accident site. The personal flight departed Crete Municipal Airport (CEK), Crete, Nebraska, at 0833, with an intended destination of Lincoln Airport (LNK), Lincoln, Nebraska.
According to radar track data, after departing CEK on runway 17, the airplane proceeded southeast and climbed to about 2,600 ft mean sea level (msl). It turned south at 0836:30 and descended to 2,400 ft msl, then turned east at 0837:44 and continued descending. Between 0839:23 and 0841:42, the airplane completed four low-altitude passes centered over a small lake about 1/3 mile northeast of the intersection of West Ash Road and Southwest 29th Road. The lake was adjacent to a residence owned by the pilot's brother. The passes and course reversals occurred within a 1/2 mile radius of the lake. Terrain elevation near the lake was about 1,470 ft msl.
The first low pass was from southeast to northwest at or below 100 ft above ground level (agl). The airplane then climbed in a right turn to about 1,900 ft msl before descending back to the lake from north to south at or below 100 ft agl. It completed a 180° turn at 1,600 ft msl, then descended for a low pass from south to north at or below 100 ft agl. The airplane then climbed in a right turn to about 1,800 ft msl before descending for a fourth low pass from northeast to southwest at or below 100 ft agl. After the fourth pass, it climbed on a southwest heading to about 2,000 ft msl, then entered a sharp right turn toward north. The final radar return at 0841:42 showed the airplane at 1,700 ft msl and about 472 ft east of the initial impact point.
The pilot's brother witnessed the airplane complete several low-altitude passes over his property. He stated that after the final low pass, the airplane pitched up into a climbing right turn, then suddenly pitched nose-down and descended rapidly. It briefly recovered to a wings-level attitude before rolling left and right and entering a descending right turn into terrain.
Personnel Information
The 68-year-old pilot held a private pilot certificate with a single-engine land airplane rating. His most recent FAA third-class medical certificate was issued on November 1, 2013, with a limitation for corrective lenses. On his medical application, he reported 323 total hours of flight experience, with 35 hours in the previous 6 months. His logbook showed a final entry on October 14, 2015, with 512.5 total hours, all in single-engine airplanes. He had logged 501.9 hours as pilot-in-command, 3.4 hours at night, and 4.3 hours in simulated instrument conditions. In the year before the accident, he flew 91.7 hours; 47.8 hours in the previous 6 months; 15.8 hours in the previous 90 days; and 5.9 hours in the previous month. He had 148.3 hours in the accident airplane make/model. His last flight review was on July 16, 2014.
The 54-year-old pilot-rated passenger held a private pilot certificate with a single-engine land airplane rating. His most recent FAA third-class medical certificate was issued on February 4, 2013, with a limitation for corrective lenses; it expired on February 28, 2015. On his medical application, he reported 222.4 total hours, with 18.5 hours in the previous 6 months. His logbook showed a final entry for a flight review on July 18, 2014, with 245.8 total hours. He had not logged any flight time in the year before the accident.
Aircraft Information
The airplane, serial number 2407, was a single-engine, low-wing, fixed conventional landing gear monoplane of conventional aluminum construction, configured for two occupants in tandem. It was powered by a 160-horsepower Lycoming IO-320-D1C engine, serial number L-5910-55A, driving a fixed-pitch two-blade Sensenich 70CM7S16-0-79 propeller, serial number 31698K. The airplane had a useful load of 628 pounds, a maximum takeoff weight of 1,600 pounds, and a total fuel capacity of 32 gallons. A previous owner assembled it from a kit. The FAA issued a special airworthiness certificate with experimental classification on October 22, 1996. The pilot purchased the airplane in November 2013.
The recording tachometer was destroyed in the postimpact fire. According to maintenance logbooks, the last condition inspection was on November 15, 2014, at 590.5 total airframe hours; the engine had also accumulated 590.5 hours since new. The final logbook entry was an oil change on October 8, 2015, at 674.5 total airframe/engine hours. No unresolved airworthiness issues were found.
Meteorological Information
At 0854, the automated surface observing system at Lincoln Airport, about 25 miles north of the accident site, reported wind 120° at 9 knots, clear sky, 10 miles visibility, temperature 8°C, dew point -1°C, and altimeter setting 30.49 inches of mercury.
Wreckage and Impact
The accident site was in a harvested soybean field. The debris path was oriented on a 265° magnetic heading and measured about 92 ft long. The initial impact crater contained the propeller and right main landing gear, with a well-defined propeller slash mark at an estimated angle of 30° to the terrain. The two-blade propeller had chordwise scratches near both tips; one blade exhibited significant S-shape bending. A large area of burnt ground surrounded the main wreckage, which included the fuselage, empennage, both wings, and the engine. Most of the fuselage, including the cockpit, was consumed by postimpact fire. Flight control continuity could not be established due to impact and fire damage; all observed separations were consistent with overstress or fire damage.
The engine remained partially attached to the firewall. Internal engine and valve train continuity was confirmed as the crankshaft was rotated. Compression and suction were noted on all cylinders. The internal oil pump discharged oil. The mechanical fuel pump exhibited fire damage and did not function. Neither magneto produced a spark when rotated by hand; both showed impact and fire damage. The upper spark plugs appeared normal. The fuel metering assembly had separated from the engine and showed impact damage. No preimpact mechanical malfunctions or failures were found that would have precluded normal engine operation.
Medical Information
Autopsies were performed on the pilot and pilot-rated passenger. The cause of death for both was multiple blunt-force injuries. Toxicology tests for the pilot were negative for ethanol; ibuprofen was detected in urine. For the passenger, tests were negative for carbon monoxide and ethanol; oxymetazoline was detected in urine but not blood. Both substances are not considered impairing.