History of Flight
On January 16, 2015, at approximately 1230 central standard time, an experimental, amateur-built Safari 400 helicopter, registration N416JB, crashed in The Woodlands, Texas, after the pilot lost control. The commercial pilot was fatally injured, and the helicopter was destroyed. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed.
Witnesses reported that the helicopter was flying southwest over the property of Woodland Church. The helicopter appeared normal as it approached the church, then suddenly turned sideways, banked left, and descended to the ground. One witness reported hearing a breaking sound and seeing the "back rotor" hanging.
Personnel Information
The 51-year-old pilot held a commercial pilot certificate with airplane single-engine land and instrument ratings. He held a second-class airman medical certificate issued on April 23, 2014, with the limitation that he must wear corrective lenses. On the medical application, the pilot reported 2,300 total flight hours, of which 150 were in the previous six months. According to his logbook, he had accumulated 48.5 total helicopter hours, including 24.0 hours in a Schweizer 269C and 25.7 hours in the accident helicopter.
Aircraft Information
The helicopter was built from a kit by Safari Helicopter. It was a two-seat, skid-equipped helicopter with two composite main rotor blades rotating clockwise and a tail rotor for anti-torque control. The engine was an Aero Sport O-360. The accident helicopter, serial number CH2181, was built by the owner of Safari Helicopters on March 1, 2010. A special airworthiness certificate was issued on March 6, 2010. The helicopter was sold to a private individual and later purchased by the accident pilot on November 6, 2014.
Meteorological Information
At 1153, the George Bush Intercontinental Airport (KIAH), 17 miles southeast of the accident site, reported calm winds, 10 miles visibility, a broken ceiling at 2,500 ft, temperature 8°C, dew point 3°C, and altimeter 30.93 inches of mercury.
Wreckage and Impact Information
The NTSB investigator-in-charge did not travel to the scene. According to FAA photographs, the main wreckage, including fuselage, main rotor, tail, and tail rotor, came to rest at the fenceline of a treed area. The horizontal stabilizer had separated and was found about 65 feet northeast of the fuselage. The right door frame was found about 85 feet northeast.
The helicopter was examined at Air Salvage of Dallas on February 24-25, 2015. The examination revealed that the horizontal stabilizer's steel tube spar had separated at the weld area just outboard of the mounting flange. The fracture exhibited corrosion and fatigue at the weld line. Paint transfers were observed on one tail rotor blade, and both blades had impact damage. Flight control continuity was established from cockpit controls to the tail rotor. The pedal cable was in the full right control pedal position. The stationary swash plate was fractured. The governor friction clutch was found loose, but an instructor pilot who recently flew the accident helicopter stated the governor operated properly. Engine continuity was confirmed, and all spark plugs were unremarkable. The carburetor was at full throttle with blue fuel present; fuel filters were clean. The main rotor blades were deformed upward; one blade was broken through the laminate and spar about 2 feet outboard of the grip. Impact marks on the tail structure were consistent with a right-to-left main rotor strike. The tail rotor drive shaft was impacted at 14.5 inches aft of the fifth bearing frame. The ignition switch was in the right position, indicating only the electronic ignition was operating. Warning indicator bulbs showed no filament stretching.
Additional Information
Following the investigation, Safari Helicopter issued a mandatory inspection and modification bulletin on April 6, 2015, titled "Horizontal Stabilizer Mandatory Inspection and Modification." The bulletin required a liquid penetrant inspection (LPI) of the horizontal stabilizer. For helicopters older than 24 months, inspection was required before next flight. If cracking was found, the spar must be replaced; if none, a steel tube insert must be installed. The bulletin noted that loss of the horizontal stabilizer would change the attitude of the helicopter, causing an abrupt, uncommanded nose-down pitch.
Medical and Pathological Information
An autopsy conducted by Montgomery County Forensic Services attributed the pilot's cause of death to multiple blunt injuries. Toxicology testing by the FAA was negative for carbon monoxide and alcohol. The medications colchicine, doxazosin, and valsartan were detected. The pilot had reported doxazosin and valsartan on his FAA medical exam; colchicine was not reported.
Tests and Research
The horizontal stabilizer and tail rotor cross were sent to the NTSB Materials Laboratory. The phenolic sleeve on the tail rotor cross was fractured at the end flange, showing brittle overstress with no discontinuities. The spar tube of the horizontal stabilizer was fractured just outboard of the mounting flange. Most of the fracture followed the outboard edge of the weld. After cleaning, magnified examinations identified features consistent with fatigue cracking. Three fatigue origins were found on the outer surface of the spar at the outboard toe of the weld, propagating radially through about half the cross section. A rust-covered crack undercutting the main fracture also exhibited fatigue features. The remaining fracture showed overstress separation consistent with forces moving the stabilizer tip forward and outboard. The weld showed good workmanship with minor defects. SEM examination confirmed fatigue cracking in alloy steel. Examination of the ignition system found no preimpact mechanical malfunction. The handheld GPS device had no tracklog information.