NTSB Factual Report

HISTORY OF FLIGHT

On February 3, 2008, about 1617 eastern standard time, an experimental amateur built RV-4, N580RG, crashed while maneuvering at Elkin Municipal Airport (ZEF), Elkin, North Carolina. The flight was operated by the pilot as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed for the flight, and no flight plan was filed. The airplane was substantially damaged by impact and a postcrash fire, and the commercial pilot, the sole occupant, was killed. The flight originated about 1612, from Elkin Municipal Airport.

The accident pilot and the pilots of 2 other airplanes departed from runway 07. After takeoff, the accident pilot turned downwind, base, and final for runway 07, and performed a low pass flying over the runway at an estimated altitude of 8 feet above ground level (agl). Witnesses reported that when the flight was near the departure end of runway 07, the airplane was observed to pitch up and roll to the left while continuing to climb. One pilot-rated witness reported that at the top of the climb at about 250 to 300 feet agl, the airplane appeared to perform a "split s" type maneuver, and the pilot appeared to have "...dished out of the roll...." The airplane began descending in a nose-low attitude, and the witness further reported that before losing sight of the airplane due to obstructions, the airplane was flying nearly perpendicular to the runway and began a rapid nose-up pitch change. The witness then observed a fireball. Friends of the pilot were at ZEF and witnessed the accident.

PERSONNEL INFORMATION

The pilot, age 64, held a commercial pilot certificate with an airplane single engine land rating issued September 12, 1969, and held a third class medical certificate issued March 1, 2006, with a limitation to have available glasses for near vision.

The pilot's logbook was not located. He listed 2,050 hours total time on the application for his last medical certificate.

AIRCRAFT INFORMATION

The amateur-built airplane was manufactured in October 1993, as model RV-4, and was designated serial number 2148. It was powered by a Lycoming O-320-B3B 160 horsepower engine and equipped with an Edward Sterba 68-70 wood fixed-pitch propeller.

The pilot purchased the airplane on September 20, 2005. The maintenance records were not located. No determination could be made as to when the airplane's last condition inspection occurred.

METEOROLOGICAL INFORMATION

A surface observation weather report taken at Wilkes County Airport (UKF), North Wilkesboro, North Carolina, at 1621, or approximately 4 minutes after the accident indicates the wind was from 070 degrees at 3 knots, the visibility was 10 statute miles, clear skies existed, the temperature and dew point were 15 and minus 02 degrees Celsius respectively, and the altimeter setting was 30.17 inches of mercury. The accident airport was located 084 degrees and 15.5 nautical miles from UKF.

COMMUNICATIONS

The ZEF airport is equipped with a common traffic advisory frequency (CTAF) of 123.05 MHz, which is not recorded. There is no information that would suggest the pilot announced on the CTAF his intention of performing low level aerobatics.

AIRPORT INFORMATION

The ZEF airport is equipped with one runway designated 07/25.

WRECKAGE AND IMPACT INFORMATION

Examination of the departure end of runway 07 revealed ground scars on grass south of the south edge of runway 07/25. The ground scars were oriented on a magnetic heading of 164 degrees. The first ground scar was located approximately 16 feet south of the south edge of the runway. Several marks on the grass continue to a berm located approximately 47 feet from the south edge of the runway. Pieces of wooden propeller blade were located at the berm. Additionally, gray colored paint was noted at the ground scars south of the runway. The airplane came to rest inverted in an area of lower elevation south of the runway. Fire damage to the ground was noted between the berm and final resting point of the wreckage.

Examination of the airplane revealed the cockpit, fuselage, and inboard portion of both wings were consumed in the postcrash fire. All components necessary to sustain flight remained attached to the airplane. Examination of the rudder and elevator flight control system revealed no evidence of preimpact failure or malfunction. Examination of the aileron flight control system revealed the left and right aluminum pushrod assemblies (Control Stick to Bellcrank, P/N W-416) were consumed by fire in each wing root area; however, each respective rod end that connects to the rear control stick remained connected at the control stick. The remaining sections of the left and right pushrod assemblies were connected at each aileron bellcrank. Further examination of the aileron flight control system revealed the right pushrod assembly (P/N W-418) was connected at the bellcrank and at the control surface. The left pushrod assembly (P/N W-418) was connected at the bellcrank but was separated from the rod end that remained connected to the control surface. Comparison of the left and right pushrod assemblies (P/N W-418) revealed the threaded rod ends at each end of the right tube were secured to it by two rivets 90 degrees apart, while only the threaded rod end at the left bellcrank was secured by rivets. The threaded rod end for the left pushrod assembly near the control surface was not secured by rivets. The left pushrod assembly and rod end were retained for further examination.

Examination of the engine with Federal Aviation Administration (FAA) oversight revealed crankshaft, camshaft, and valve train continuity during hand rotation of the crankshaft. Fire damage to the engine and engine accessories precluded an engine run. The magnetos and carburetor were heat damaged which precluded bench testing. The spark plug electrodes were light gray in color consistent with normal fuel/air metering. No evidence of preimpact failure or malfunction of the engine or engine accessories was noted.

Examination of the two-bladed wood propeller which remained attached to the engine revealed both blades were shattered and heat damaged to the root end of each blade. As previously reported, sections of propeller blade were noted at the initial ground impact location.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot was performed by Wake Forest University School of Medicine Department of Pathology. The cause of death was listed as "blunt force injuries to head and torso." The autopsy report did not indicate the pilot was wearing a parachute.

Forensic toxicology was performed on specimens of the pilot by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The results were negative for carbon monoxide, cyanide, volatiles, and tested drugs.

TESTS AND RESEARCH

The pilot landed at ZEF approximately 1.5 hours earlier, and prior to landing, the accident pilot performed a low pass over runway 25. When the flight was past the departure end of runway 25, the accident pilot was noted to perform a "poorly executed aileron roll." After completing the roll, the accident pilot remained in the traffic pattern, landed uneventfully on runway 25, and then secured the airplane. There was no evidence indicating the pilot reported on the CTAF that he intended to perform low level aerobatics. The airport manager who is also a pilot and was at the airport at the time did not discuss the low level aerobatics issue with the accident pilot.

Examination of the left pushrod assembly (P/N W-418) was performed by the National Transportation Safety Board's Materials Laboratory. The rod end and threaded rod end assembly that connect to the aileron flight control surface exhibited a bend of approximately 3 degrees centered where the thread portion of the threaded rod end joined the plain diameter portion. There were no holes in the tube or evidence of welding in which the threaded rod end was secured to the steel tube. Additionally, there were no observed marks on the plain diameter portion to indicate that extraction had occurred at intervals during operation prior to the impact.

Safety Board review of the engineering drawing associated with the pushrod assembly (P/N W-418) bellcrank to aileron revealed that two AN470AD4-12 rivets are required to secure each threaded rod end to each end of the steel tube, though the drawing only depicts rivets at the end closest to the aileron. The opposite end of the pushrod depicts an option is to weld in place of rivets.

Review of 14 CFR Part 91.303 indicates that no person may operate an aircraft in aerobatic flight below an altitude of 1,500 feet above the surface. The regulation specifies that aerobatic flight is defined as an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight. Review of 14 CFR Part 91.307 indicates that unless each occupant of the aircraft is wearing an approved parachute, no pilot of a civil aircraft may execute any intentional maneuver that exceeds a bank of 60 degrees relative to the horizon.

The airplane designer publishes a newsletter called RVator six times a year, and considers the RVator to be the, "...main method of communication between the company and its customers." According to company personnel, the issue about unsecured rod ends was first published in the RVator in 1993. The issue of unsecured rod ends was again republished as filler in the sixth issue 2007. Safety Board review of that issue revealed three stories related to unsecured rod ends. The first story related to in-flight separation of the elevator flight control pushrod assembly that connects the front and rear control sticks. One end of the pushrod disconnected from the rod end rendering the front control stick inoperative for pitch. The pilot landed the airplane successfully using the front stick for aileron control and the rear stick for pitch control. The second story related to disconnection of an aileron pushrod from the rod end during ground test of the flight controls. The third story relates to in-flight separation of the elevator flight control pushrod from the rear stick. The aerobatic pilot baled out of the airplane. Personnel from the airplane designer also reported that if the aileron pushrod assembly were to disconnect in-flight, the roll rate would be half of normal, or approximately 180 degrees in 3 seconds.

Safety Board examination of a RV-3 and RV-4 airplanes at the accident airport were performed the day after the accident. The purpose of the inspection was to document the aileron pushrod assemblies to see whether they were properly secured. The RV-3 airplane which was built by an experimental aircraft association (EAA) chapter did not have any rivets securing the pushrod to the rod end. The RV-4 airplane did have rivets securing the pushrod to the rod end.

NTSB Probable Cause

The pilot's decision to attempt an aerobatic maneuver in close proximity to the ground.