History of Flight
On October 22, 2011, at about 1251 eastern daylight time, a Berger Waiex experimental amateur-built airplane, registration N75654, sustained substantial damage following an inflight breakup and collision with terrain near Washington, Georgia. The certificated sport pilot was killed. The airplane was operated by the pilot under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed; no flight plan was filed. The local flight departed Washington-Wilkes County Airport (IIY) at about 1239.
Radar and Garmin 510 GPS data showed the airplane departed IIY and began a gradual climbing turn north. About 2 nautical miles northeast of IIY, it climbed in left-hand circles to a peak altitude of 4,700 feet mean sea level, then continued west until GPS data ended. The last two radar returns with altitude were at 4,600 and 4,300 feet. Prior to the last return, the airplane was in a slight descent and accelerated to about 100–110 knots ground speed. The GPS did not capture parameters when control was lost. The wreckage was found about 0.11 nautical mile north-northeast of the last radar return.
Deer hunters about a quarter-mile northwest heard a loud noise and saw what they thought was the airplane's tail falling. They also heard the engine stop before the crash and called 911. Another witness heard the engine stop and saw the airplane tumbling "end over end" through trees.
Pilot Information
The pilot held a sport pilot certificate issued November 3, 2009, and reported 29.9 total flight hours on his application, including 5.8 as pilot-in-command. His personal logbook was not found, but maintenance logbooks indicated about 53 hours of flight time on the aircraft since he purchased it on April 13, 2011.
Aircraft Information
The Waiex ("Y-X") is a Sonex in a Y-tail configuration, built in 2007 by the original builder. It was a single-engine, low-wing, fixed tailwheel airplane, serial number WX-0087, powered by an Aerovee 2.1 engine rated at 80 horsepower. Total time since manufacture was about 300 hours. The last condition inspection was February 12, 2011, at 144.2 hours. The last airframe maintenance (brake change) was October 21, 2011, at 300.6 hours; last engine maintenance (oil, filter, spark plugs) was September 28, 2011.
Meteorological Information
The 1351 surface observation at Athens, Georgia (28 nautical miles west-northwest) reported calm wind, visibility 10 miles or better, clear sky, temperature 18°C, dew point 4°C, altimeter 30.12 inHg.
Wreckage and Impact Information
The main wreckage, except the Y-tail, was in a wooded ravine about 2.3 nautical miles north of IIY. The Y-tail was found separated about 550 feet southwest of the main wreckage. The fuselage was inverted against a pine tree; the engine and propeller remained attached. One propeller blade was broken off at the root; blades showed no rotational damage. The fuel tank contained less than one ounce of fuel, was not breached, and no fuel odor or spill was evident.
Flight control continuity was established for ailerons and Y-tail attachment points. Construction examination revealed several areas of less-than-optimal techniques, including lack of deburring, notching, excessive chamfers, mis-drilled holes, and oversized washers covering mis-drilled holes.
The throttle was about 0.25 inches aft of full forward; mixture was full forward. The engine rotated freely, compression and suction were present on all cylinders. The carburetor showed no obstructions or contamination. Spark plug electrodes were light gray.
Medical and Pathological Information
Postmortem examination on October 25, 2011, listed cause of death as multiple blunt force injuries, manner accident. The pilot had an enlarged heart with coronary atherosclerotic disease; no acute or remote infarcts were found. Toxicology was negative for carbon monoxide, cyanide, and ethanol. Metoprolol, rosuvastatin, and ticlopidine were detected. The pilot did not hold a current FAA medical certificate; his last special issuance third-class medical expired December 31, 2009, noting a history of angina, coronary artery disease, hypertension, and post-traumatic stress disorder.
Tests and Research
NTSB Materials Laboratory examined Y-tail components. The forward tail connection (lower attach angle) showed tensile and shear overstress fracturing with no fatigue indications. The vertical flange had a 2.5–3 inch tensile overstress region on the right edge; the rest fractured by shear. Bolt holes showed elongation. The aft tail connection consisted of two Y-shaped plates with similar overstress fractures in the vertical direction, no fatigue, and plastic deformation on the left side. Not all surfaces or holes were clean or deburred.
The breakup sequence appeared to initiate at the forward Y-tail attachment structure (lower attach angle), which separated in tension from right to left, followed by fracture of the aft Y-fitting.
Additional Information
The Waiex was designed by Sonex Aircraft, LLC, using pre-1996 CFR Part 23 Appendix A simplified design load criteria. No design standards are required for experimental amateur-built airplanes. The pre-1996 Appendix A applied to conventional single-engine airplanes of 6,000 pounds or less, but CAR Part 3 specifically stated that design charts for control surface loads did not apply to V-tails. The 1996 revision of Appendix A explicitly excluded V-tail configurations from using the criteria. After the accident, Sonex issued service bulletin WIX-SB-001 to add an aluminum block at the tension separation point.