History of Flight
On December 13, 2008, at 1206 eastern standard time, an Ercoupe 415-D, N99154, was destroyed during an in-flight breakup near Sebring, Florida. The certificated commercial pilot and passenger were fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which departed Avon Park Executive Airport (AVO), Avon Park, Florida, about 1115. The flight was conducted under 14 CFR Part 91.
According to a friend of the pilot, also a certificated aircraft mechanic, he and the pilot flew together in the accident airplane on a sightseeing flight immediately before the accident flight. The friend noted no abnormalities with the performance of the airplane or pilot, and after returning to AVO, the friend disembarked and the passenger boarded.
Numerous witnesses observed the airplane. One witness saw the airplane flying southwest, make a slight dip, turn right, then pull up severely and turn left. As it continued upward and banked left, something "shiny" exited the tail area, and the airplane began to break apart. No explosion, smoke, or fire was observed. Another witness, an airline transport pilot, heard an abnormal engine sound about 45 minutes after first seeing the airplane. The engine sound was smooth and continuous, as if being over-sped at full power in a high-speed dive. He saw the airplane pitch up and roll into a steep left bank, initially thinking a barrel roll was attempted. Both ailerons were fluttering at high frequency. The bank angle reached nearly 90 degrees when the left wing folded back and separated. The airplane pivoted, the right wing separated along with a portion of the cabin, and the wings fluttered to the ground. Three distinct thuds were heard upon impact. The witness noted "confetti"-like painted dope chips from the fabric-covered wings.
Meteorological Information
At 1152, weather at Bartow Municipal Airport (BOW), about 24 nautical miles west, included winds from 020 degrees at 9 knots gusting to 15 knots, 20 statute miles visibility, clear skies, temperature 16°C, dewpoint 6°C, and altimeter 30.21 inHg.
Personnel Information
The pilot, age 70, held a commercial pilot certificate with ratings for airplane single-engine land and sea, multiengine land, and instrument airplane, as well as a flight instructor certificate. His most recent second-class medical certificate was issued June 2, 2008. His logbook showed 7,126 total flight hours, with 12 hours in the accident make and model.
Aircraft Information
The airplane was manufactured in 1946. According to maintenance records, the most recent annual inspection was completed May 9, 2008, at which time the airplane had accumulated 2,588 total hours.
Wreckage and Impact Information
The in-flight breakup occurred over a residential golf-course community where the passenger resided. Wreckage was scattered along a 3,100-foot path oriented on a magnetic heading of about 020 degrees. The first pieces included aft cabin windows. Further along were paint chips, inspection panels, and personal effects. The right wing, located about 2,000 feet from the cabin windows, was lodged in the ground perpendicular to the terrain, largely intact but separated at the wing root just inboard of the leading edge fuel tank. The wing spar remained intact to about 1 foot inboard. Ten of 17 right-wing inspection port covers were dislodged, mostly from the root, leading edge, and outboard edge. The left wing was found about 900 feet beyond the right, with a similar spar fracture. Several left-wing covers were dislodged without a discernable pattern. Inboard portions of both wing spars were sent to the Safety Board Materials Laboratory.
The main wreckage (nose, cabin, aft fuselage) came to rest about 200 feet beyond the left wing, contained in a 10x10-foot area with extensive crush damage. The cabin was severely compromised, and the seat pan with both occupants was 125 feet north of the main wreckage. The empennage and stabilizers remained largely intact but separated. The propeller remained attached to the engine with chordwise scratching and burnishing. Aileron and rudder control continuity was traced to the mixing bellcrank aft of the main spar carrythrough, with separations at wing roots and elevator push-pull tube separated about 1 foot forward of its bellcrank.
Medical and Pathological Information
An autopsy on the pilot listed the cause of death as "blunt impact." Toxicological testing by the FAA showed no carbon monoxide, cyanide, ethanol, or drugs.
Additional Information
The inboard portions of both separated wing spars were examined. According to the Materials Laboratory report, deformation of the top spar cap and fracture surfaces were consistent with ductile overstress in aft and downward bending of the center wing spar. An apparent modification reduced the cross-sectional area of the top spar cap by 10 percent. Three screw holes were observed, with a broken self-tapping screw in one hole. The original design specified two holes 1 inch apart longitudinally; the third hole, not in the design, was located between them and threaded for a larger screw. Radial lines on the fracture surface emanated from the screw holes, with shear lips and necking consistent with tensile overstress. No evidence of fatigue was found, and no corrosion was observed.