Accident Details
Probable Cause and Findings
The improper execution of an autorotation following the loss of engine power, which resulted in an uncontrolled descent into terrain. Contributing to the accident was the flight instructor's lack of remedial action during the autorotation.
Aircraft Information
Registered Owner (Historical)
Analysis
HISTORY OF FLIGHTOn August 9, 2016, at 2035 central daylight time, a Hughes 269C helicopter, N9277R, impacted terrain following an autorotation near Howe, Texas. The flight instructor was fatally injured, the student pilot sustained serious injuries, and the helicopter sustained substantial damage. The helicopter was privately owned and operated under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The local instructional flight departed the Sherman Municipal Airport (SWI), Sherman, Texas, at an unknown time.
The student pilot reported to a law enforcement officer who responded to the accident that he and the flight instructor were flying about 1,100 ft above ground level (agl) when the instructor initiated a practice autorotation which included reducing the throttle to idle to simulate an engine failure. When the engine power was reduced, the engine experienced a total loss of power. The flight instructor attempted to restart the engine, but was unsuccessful. The student stated that the autorotation was initially controlled, but then the helicopter impacted terrain in a high-speed descent. During the impact, the tail boom partially separated, and the helicopter rolled over, coming to rest on its right side.
In a written statement, the student reported that he and the instructor had completed some landings and other operations at SWI, and were returning to his residence at an altitude about 1,200 ft agl. While en route, the instructor "slowly rolled down the throttle to simulate [an] engine failure." After noticing the throttle reduction, the student lowered the collective and looked for an appropriate place to land. The student and instructor then noticed the engine rpm gauge was reading zero. The student stated that both he and the instructor were "on the controls" during the autorotation. The student recalled starting to flare about 25 ft agl, and did not recall any details after the flare. The student reported, "I feel we didn't slow the descent enough before contacting the ground..." The student exited the helicopter and attempted, unsuccessfully, to extricate the instructor. He then went to search for assistance.
According to a Federal Aviation Administration (FAA) inspector, who spoke with the student after the accident, the student stated that the instructor never touched or manipulated the flight controls during the flight and during the accident sequence. PERSONNEL INFORMATIONAccording to the FAA inspector who spoke with the student, the student had accumulated 25 flight hours with a local helicopter flight school before flying with the accident instructor. He'd stopped flying with the local flight school in October 2012. Since October 2015, the student had flown several flights with the instructor and had accumulated 63.7 total flight hours at the time of the accident.
According to law enforcement, on July 12, 2014, the student had been involved in a previous accident in the same make/model helicopter. The student stated to the FAA inspector that he was moving the helicopter when the helicopter "got away from him." The accident was not reported to the NTSB. AIRCRAFT INFORMATIONThe helicopter's most recent annual inspection (which included an annual, 100, 200, 400 and 24-month inspections) was completed on August 10, 2015, at a total airframe time of 5,624 hours and a Hobbs meter time of 13.0 hours. At the time of the inspection, the engine had accumulated 3,664.6 total hours and 392.6 hours since overhaul. The Hobbs meter time at the accident site was 52.7 hours.
Review of maintenance records revealed no entries or comments related to idle/mixture adjustments or settings. METEOROLOGICAL INFORMATIONReview of sun and moon data from the U.S. Naval Observatory revealed that, on the day of the accident, sunrise was at 0644, sunset was 2018, and the end of civil twilight was 2045. AIRPORT INFORMATIONThe helicopter's most recent annual inspection (which included an annual, 100, 200, 400 and 24-month inspections) was completed on August 10, 2015, at a total airframe time of 5,624 hours and a Hobbs meter time of 13.0 hours. At the time of the inspection, the engine had accumulated 3,664.6 total hours and 392.6 hours since overhaul. The Hobbs meter time at the accident site was 52.7 hours.
Review of maintenance records revealed no entries or comments related to idle/mixture adjustments or settings. WRECKAGE AND IMPACT INFORMATIONThe helicopter impacted down sloping grassy terrain adjacent to wooded areas and residential structures. The main wreckage consisted of the fuselage, a portion of the tail boom, and the main rotor system. The landing gear skids were spread apart and bent up into the fuselage. The instrument panel was partially separated from the fuselage. The fuel boost pump switch was found in the OFF position. The right seat anti-torque pedals were separated from the pedal supports. Both the left and right seat bottom panels were crushed downward about 4 inches. Flight control continuity was established from the cockpit to all flight controls in the main rotor and tail rotor systems. The three main rotor blades were bent and deformed, and remained attached to the rotor head.
Upon their arrival to the accident site, first responders noted that fuel was draining from the fuel tanks.
The helicopter was recovered to a secure storage facility for further examination.
On August 30, 2016, the helicopter was examined by the NTSB investigator-in-charge, a representative from the FAA rotorcraft directorate, representatives from Sikorsky Aircraft, and a representative from Lycoming Engines.
Examination of the airframe revealed the mast was intact and three support struts were straight and attached. The transmission was intact and remained attached to the steel center frame. The steel tube support frame exhibited bending, buckling, and fractures. The two forward cockpit floor support struts were fractured. The cockpit floor was separated from the base of the seat deck. The door frames were fractured and separated. The aft cabin wall was distorted and wrinkled at bottom attach area to the seat deck. The canopy frame was fractured and separated with all Plexiglas broken and separated.
The main rotor blades remained attached to the rotor head, and the blades were intact. The yellow blade was bent up at the root end doubler, bowed down at mid-span, and upward at the blade tip. Chordwise crushing and trailing edge wrinkles were noted about mid-span. White paint transfer, consistent with contact with the airframe, was noted on the bottom leading edge. The blue blade was bent downward at the root end doubler, bowed upward near mid-span, and downward at the tip. White paint transfer was present near the blade tip. The red blade was bent downward at the root end doubler. The blade was relatively straight.
The main rotor head was intact and attached to the drive shaft. The rotor head turned freely in the mast bearing with continuity through the main gear box. The three upper main rotor hub attach bolts exhibited compression damage. The compression damage was consistent with contact from the pitch bearing shaft from a high upward blade movement. The blade up-flapping/coning was consistent with blade to ground contact. The droop stop ring was not present.
The tail boom was fractured at the center bulkhead rivet line, and the forward section was separated from the steel tube frame and strut at the forward bulkhead. Both tail boom support struts were fractured at the lower tabs in a downward direction. A main rotor blade contact dent was noted aft of the center attach fitting, at the internal damper location. The left support strut remained attached to the tail boom and exhibited a long black mark on the outside lower portion of the tube, consistent with main rotor blade contact. The horizontal stabilizer displayed downward bending damage and skin buckling at the forward attachment to the tail boom. The lower vertical stabilizer sustained crush damage consistent with ground contact.
The tail rotor blades remained attached to the hub. Both blades displayed minor airfoil damage. One blade was intact and straight, and one blade was fractured at the end of the hub. The tail rotor driveshaft was separated at the forward end from the main gear box pinion drive spline. The driveshaft remained in one piece, but was buckled and folded aft at the boom separation point. The driveshaft exhibited torsional twisting near the forward end with twisting in the direction of rotation, consistent with tail rotor contact prior to separation.
The left landing gear skid remained attached to the forward cross beam at the strut and damper. The left aft skid was separated at the strut to cross beam, with the fracture consistent with overload failure. The right landing gear skid forward strut remained attached to the crossbeam, and the aft strut separated at the crossbeam. The skid was bent between the forward and aft strut attach points, and fractured forward of the forward strut.
The engine remained partially attached to the airframe. The exhaust pipes were crushed, deformed, and displaced, consistent with ground contact. The fuel injector body exhibited impact marks consistent with forward landing gear crossbeam contact. The throttle bellcrank linkage was fractured and separated from the bottom of inlet adapter mount.
Engine control continuity was established from the cockpit controls to the engine components; however, full motion was restricted due to airframe deformation. Thumb compression and valve motion was noted on all cylinders. The magnetos were removed and rotated with a portable drill, and all eight spark plug leads produced spark. The fuel injector nozzles were removed and all nozzles exhibited some carbon on the orifice tips. The fuel injector body bore exhibited carbon deposits. The drained oil from the cr...
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# CEN16FA315