ERA12FA018

The in-flight failure of the aircraft’s Y-tail attachment structure during maneuvering flight due to overload. Contributing to the accident was, the kit manufacturer’s use of 14 CFR Part 23, Appendix A design guidelines intended for a conventional tail airplane without a V- (or Y-) tail.

Radar and global positioning system (GPS) information showed that the sport pilot took off from his home airport and initiated a climbing left turn until an altitude of 4,700 feet mean sea level (msl) was reached. The experimental, amateur-built (E-AB) airplane then continued on a westerly heading until the GPS stopped recording data. The last recorded radar return with altitude information was at 4,300 feet. Before the last radar return, the airplane was in a slight descent and had accelerated to about 100 to 110 knots ground speed. Witnesses reported that the engine stopped running in flight, and the tail separated before the airplane collided with the ground. Examination of the wreckage revealed that the airplane’s fuel system was empty and the propeller showed no evidence of rotation at impact. The airplane’s “Y-tail,” which was essentially the same as a V-tail, was found about 550 feet from the main wreckage, which confirmed that the airplane broke up in flight. The breakup appeared to have initiated in the forward Y-tail attachment structure, which was an aluminum attach angle. The lower attach angle separated in tension along the right side and further separated with the fracture running from the right to the left. When the lower attach angle broke, the structure that formed the aft connection Y-fitting also fractured and separated. Due to a lack of GPS data and the typical sample rate of radar data, the exact circumstances, including precise airspeed and any maneuvering leading up to the breakup, are not known. It is likely that the pilot, distracted by the loss of engine power, allowed the airplane to enter an unusual attitude, and the tail separated during the pilot’s attempted recovery from the unusual attitude. Although there were (and are) no required design standards or criteria for E-AB airplanes, the kit designer used a pre-1996 version of 14 Code of Federal Regulations Part 23, Appendix A, when he designed the airframe. The pre-1996 version stated that the design load criteria in the appendix were an approved equivalent for the certification of conventional, single-engine airplanes of 6,000 pounds or less maximum weight. The 1996 revision of Appendix A removed the reference to conventional airplane and added an expanded section defining the applicability of Appendix A. The expanded definition explicitly excluded using Appendix A criteria when designing the V-tail configurations of certified airplanes. In general, the surface loads on a V-tail configuration may be greater than the design loads expected on the surfaces of a conventional tail airplane. The airplane was designed in the 2002 to 2003 timeframe and the first plans were sold in 2004.

HISTORY OF FLIGHT On October 22, 2011, about 1251 eastern daylight time, a Berger Waiex, N75654, was substantially damaged following an inflight breakup and collision with terrain near Washington, Georgia. The certificated sport pilot was killed. The experimental, amateur-built (E-AB) airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed and no flight plan was filed. The local flight originated at Washington-Wilkes County Airport (IIY), Washington, Georgia about 1239. A review of radar and Garmin 510 Global Positioning System (GPS) data revealed that the airplane departed IIY about 1239, and the pilot began a gradual, climbing turn to the north. About 2 nautical miles (nm) northeast of IIY, the airplane was observed climbing in left-hand circular patterns until a peak altitude of 4,700 feet above mean sea level (msl) was reached. The airplane then continued on a westerly heading until the GPS stopped recording data. The last two recorded radar returns with altitude data were at 4,600 and 4,300 feet. Prior to the last radar return, the airplane was in a slight descent and accelerated to about 100 to 110 knots ground speed. The GPS did not capture the parameters when aircraft control was lost. The wreckage site was located about 0.11 nm north-northeast of the last radar return with altitude information. Local deer hunters were outside, about one-quarter mile northwest of the accident site, at the time of the accident. They heard a loud noise and looked up to see what they thought was the airplane's tail, falling out of the sky. They also heard the engine stop running prior to the crash. They immediately proceeded toward the accident site and called 911 for assistance. Another witness, who was outside his residence at the time of the accident, reported that he heard the airplane's engine stop running. He could see the airplane through the trees on his property, and the airplane was tumbling downwards, "…end over end." PERSONNEL INFORMATION The pilot held a sport pilot certificate, issued November 3, 2009. He reported a total flight experience of 29.9 hours on his sport pilot certificate application, including 5.8 hours as pilot in command. The pilot's personal logbook was not located; however, according to the maintenance logbooks, about 53 hours of flight time were recorded on the aircraft since the pilot purchased it on April 13, 2011. AIRCRAFT INFORMATION The airplane was built in 2007 and the pilot purchased it from the builder. According to representatives from Sonex Aircraft, LLC, the kit manufacturer, a Waiex (pronounced "Y-X") is a Sonex in a "Y-tail" configuration. For the purposes of this report, the terms "V-Tail" and "Y-Tail" are used interchangeably. According to the maintenance logbooks, the airplane had accumulated about 300 hours total time since its manufacture. The airplane was a single engine, low wing, fixed tail wheel airplane, serial number WX-0087. It was powered by an Aerovee 2.1 engine rated at 80 horsepower. According to the aircraft maintenance records, the last condition inspection on the airframe and engine was performed on February 12, 2011, at a total aircraft time of 144.2 hours. The last recorded airframe maintenance occurred on October 21, 2011, at 300.6 hours total aircraft time, when the brakes were changed. The last recorded engine maintenance occurred on September 28, 2011, when the oil, oil filter, and spark plugs were changed. METEOROLOGICAL INFORMATION The 1351 surface weather observation for Athens, Georgia (AHN), located about 28 nautical miles (nm) west-northwest of the accident site, reported wind calm, visibility 10 miles or better, sky clear, temperature 18 degrees C, dew point 4 degrees C, and altimeter setting 30.12 inches of mercury. WRECKAGE AND IMPACT INFORMATION The aircraft wreckage, except for its Y-tail assembly, was found in a wooded ravine, about 2.3 nautical miles north of IIY. The coordinates of the main wreckage were 33 48.97N and 082 49.23W. The Y-tail was found separated, near a dirt road, about 550 feet southwest of the main wreckage. The coordinates of the Y-Tail were 33 48.91N and 082 49.31W. The fuselage was found inverted, resting against a pine tree. The engine remained attached to the airframe and the propeller remained attached to the engine. One blade of the propeller was broken off at the root; the other blade remained attached to the hub. The blades did not display evidence of rotational damage. The aircraft fuel tank contained less than one ounce of fuel and was not breached. There was no odor of fuel observed at the main wreckage site. There was no evidence of spilled fuel under the wreckage. Flight control continuity was established from the ailerons to the cockpit controls. The flaps were observed in the "retracted" position. Control continuity was established from the cockpit controls to the fractured surface attachment points on the Y-tail. General examination of the aircraft structure revealed several areas of "less-than-optimal" construction techniques. These included a lack of deburring drilled holes, notching from metal cuts that were not smoothed out, excessive chamfers, mis-drilled holes, and the use of oversized washers to cover mis-drilled holes. For more information on this subject, refer to the Structures Study, located in the public docket for this accident. The engine throttle was found about 0.25 inches aft of the "full forward" position. The fuel mixture knob was in the "full forward" position. The engine was free to rotate when the crankshaft was turned by hand. Compression and suction was observed on all cylinders when the crankshaft was rotated. The carburetor was removed for examination; it showed no evidence of obstructions or contamination. The spark plug electrodes were light gray in color and did not exhibit abnormal wear. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination of the pilot was performed by the Georgia Bureau of Investigation, Division of Forensic Sciences, on October 25, 2011. The autopsy report noted the cause of death as "Multiple blunt force injuries" and the manner of death was "Accident." The report also noted that the pilot had "…an enlarged heart with coronary atherosclerotic disease." There was no evidence of acute or remote infarcts. Forensic toxicology testing was performed on specimens of the pilot by the Federal Aviation Administration (FAA) Bioaeronautical Sciences Research Laboratory (CAMI), Oklahoma City, Oklahoma. The CAMI toxicology report indicated negative for carbon monoxide, cyanide, and ethanol. Metoprolol and rosuvastatin were detected in the urine and blood, and ticlopidine was detected in the urine, but not in the blood. Metoprolol (Toprol XL ®) is a prescription selective beta1-adrenoreceptor blocking agent used to treat high blood pressure, angina and control heart rate in some arrhythmias. Rosuvastatin (Crestor®) is a prescription lipid lowering agent used to treat elevated blood lipids and elevated cholesterol. Ticlopidine (Ticlid®) is a prescription platelet aggregation inhibitor used as adjunctive therapy with aspirin to reduce the incidence of subacute stent thrombosis in patients undergoing successful coronary stent implantation; it is also used to reduce the risk of stroke in people who have had a stroke or have had warning signs of a stroke and who cannot be treated with aspirin. The pilot did not possess a current FAA airman medical certificate. He possessed a valid and current Georgia driver’s license. He was issued a Special Issuance (SI) third class airman medical certificate on December 1, 2008, with an expiration date of December 31, 2009. The pilot did not apply for a renewal of the SI. The SI noted a history of angina pectoris, coronary artery disease requiring percutane