What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
1963 Bell UH-1B helicopter crashed on take-off and sustained substantial damage, other circumstances are unknown.(-23) a BHT-UH1B heli, N99SJ, serial #1025, crashed on departure during agricultural spraying operations,in a field located approx. 13.5 miles west north west from Lost Hills, CA. 93249. After take-off, while maintaining four to five feet skid height, the heli went through effective transitional lift, and continued to gain airspeed. Beteen 20 to 30 mph ground speed the PIC heard a loud bang, the heli Lost directional control. The heli made approx. three 360 degree right turns before contacting the ground. After the heli contacted the ground the forward section of the completely cracked 90 degree gearbox fell to the ground. (.4)during the takeoff initial climb as the helicopter accelerated through 25 to 30 miles per hour, the 90-degree gearbox fractured through the center of the gearbox case and separated from the tailboom. The pilot was able to slow the spin rate and performed a hovering autorotation. A portion of the tail boom impacted a barbed wire fence as the helicopter settled vertically. Metallurgical examination of the gearbox case fractures disclosed overload features. Internal examination of the gearbox and gears showed that the pinion and gear teeth had disengaged. The disengagement lasted a short period of time. As a result of the disengaged gear and pinion rotating against each other, the gearbox case became overloaded and subsequently separated. The wear patterns on the pinion and gear teeth drive side did not meet the patterns specified in the maintenance manual; the patterns extended off the toe ends and the tips of the teeth. The gearbox, which is an 'on-condition' component, was last overhauled or repaired in 1984. There is no requirement for an internal inspection of the tail rotor gearbox during routine or annual maintenance inspections.
As the FAA filed it
1963 BELL UH-1B HELICOPTER CRASHED ON TAKE-OFF AND SUSTAINED SUBSTANTIAL DAMAGE, OTHER CIRCUMSTANCES ARE UNKNOWN.(-23) A BHT-UH1B HELI, N99SJ, SERIAL #1025, CRASHED ON DEPARTURE DURING AGRICULTURAL SPRAYING OPERATIONS,IN A FIELD LOCATED APPROX. 13.5 MILES WEST NORTH WEST FROM LOST HILLS, CA. 93249. AFTER TAKE-OFF, WHILE MAINTAINING FOUR TO FIVE FEET SKID HEIGHT, THE HELI WENT THROUGH EFFECTIVE TRANSITIONAL LIFT, AND CONTINUED TO GAIN AIRSPEED. BETEEN 20 TO 30 MPH GROUND SPEED THE PIC HEARD A LOUD BANG, THE HELI LOST DIRECTIONAL CONTROL. THE HELI MADE APPROX. THREE 360 DEGREE RIGHT TURNS BEFORE CONTACTING THE GROUND. AFTER THE HELI CONTACTED THE GROUND THE FORWARD SECTION OF THE COMPLETELY CRACKED 90 DEGREE GEARBOX FELL TO THE GROUND. (.4)DURING THE TAKEOFF INITIAL CLIMB AS THE HELICOPTER ACCELERATED THROUGH 25 TO 30 MILES PER HOUR, THE 90-DEGREE GEARBOX FRACTURED THROUGH THE CENTER OF THE GEARBOX CASE AND SEPARATED FROM THE TAILBOOM. THE PILOT WAS ABLE TO SLOW THE SPIN RATE AND PERFORMED A HOVERING AUTOROTATION. A PORTION OF THE TAIL BOOM IMPACTED A BARBED WIRE FENCE AS THE HELICOPTER SETTLED VERTICALLY. METALLURGICAL EXAMINATION OF THE GEARBOX CASE FRACTURES DISCLOSED OVERLOAD FEATURES. INTERNAL EXAMINATION OF THE GEARBOX AND GEARS SHOWED THAT THE PINION AND GEAR TEETH HAD DISENGAGED. THE DISENGAGEMENT LASTED A SHORT PERIOD OF TIME. AS A RESULT OF THE DISENGAGED GEAR AND PINION ROTATING AGAINST EACH OTHER, THE GEARBOX CASE BECAME OVERLOADED AND SUBSEQUENTLY SEPARATED. THE WEAR PATTERNS ON THE PINION AND GEAR TEETH DRIVE SIDE DID NOT MEET THE PATTERNS SPECIFIED IN THE MAINTENANCE MANUAL; THE PATTERNS EXTENDED OFF THE TOE ENDS AND THE TIPS OF THE TEETH. THE GEARBOX, WHICH IS AN 'ON-CONDITION' COMPONENT, WAS LAST OVERHAULED OR REPAIRED IN 1984. THERE IS NO REQUIREMENT FOR AN INTERNAL INSPECTION OF THE TAIL ROTOR GEARBOX DURING ROUTINE OR ANNUAL MAINTENANCE INSPECTIONS.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.