What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Shortly after departure. Issued may day. Seen spiral to impact. Crankshaft broke off at prop assembly in flight. (.19) on August 17, 1997, at 1300 hours pacific daylight time, an experimental hefner-pitts, S1S, N10HJ, was destroyed during a forced landing at Van Nuys, CA. The pilot received fatal injuries. Visual meteorological conditions prevailed for the personal flight, and no flight plan was filed. The flight departed from runway 16R at the Van Nuys Airport and the pilot requested a right-hand downwind departure to the practice area. During the departure, about 1.5 miles northwest of the airport, the pilot declared "mayday" three times on the tower frequency. Tower personnel observed the aircraft spiraling downward. Witnesses stated that the aircraft descended at a 45-degree angle into the four land residential area street. A path of wreckage debris paralleled the east-west street over a distance of 281 feet. (.4) the pilot departed and requested a right-hand departure to the practice area. During the downwind departure he declared an emergency and witnesses observed the aircraft spiraling downward at a 45-degree angle into a residential street. Parts from the aircraft were found some distance from the accident site. The propeller along with the severed crankshaft flange were found still bolted together less part of one propeller blade. Metallurgical examination revealed that a blade had failed midspan due to fatigue. The propeller was being operated above the design RPM red line of 2,700. Additionally, the propeller was being subjected to gyroscopic aerobatic loads. An RPM restriction for the propeller mandated by an airworthiness directive was not placarded on the instrument panel per the AD. The engine was designed for a type certificated helicopter application and was approved for a 3,200 RPM red line.
As the FAA filed it
SHORTLY AFTER DEPARTURE. ISSUED MAY DAY. SEEN SPIRAL TO IMPACT. CRANKSHAFT BROKE OFF AT PROP ASSEMBLY IN FLIGHT. (.19) ON AUGUST 17, 1997, AT 1300 HOURS PACIFIC DAYLIGHT TIME, AN EXPERIMENTAL HEFNER-PITTS, S1S, N10HJ, WAS DESTROYED DURING A FORCED LANDING AT VAN NUYS, CA. THE PILOT RECEIVED FATAL INJURIES. VISUAL METEOROLOGICAL CONDITIONS PREVAILED FOR THE PERSONAL FLIGHT, AND NO FLIGHT PLAN WAS FILED. THE FLIGHT DEPARTED FROM RUNWAY 16R AT THE VAN NUYS AIRPORT AND THE PILOT REQUESTED A RIGHT-HAND DOWNWIND DEPARTURE TO THE PRACTICE AREA. DURING THE DEPARTURE, ABOUT 1.5 MILES NORTHWEST OF THE AIRPORT, THE PILOT DECLARED "MAYDAY" THREE TIMES ON THE TOWER FREQUENCY. TOWER PERSONNEL OBSERVED THE AIRCRAFT SPIRALING DOWNWARD. WITNESSES STATED THAT THE AIRCRAFT DESCENDED AT A 45-DEGREE ANGLE INTO THE FOUR LAND RESIDENTIAL AREA STREET. A PATH OF WRECKAGE DEBRIS PARALLELED THE EAST-WEST STREET OVER A DISTANCE OF 281 FEET. (.4) THE PILOT DEPARTED AND REQUESTED A RIGHT-HAND DEPARTURE TO THE PRACTICE AREA. DURING THE DOWNWIND DEPARTURE HE DECLARED AN EMERGENCY AND WITNESSES OBSERVED THE AIRCRAFT SPIRALING DOWNWARD AT A 45-DEGREE ANGLE INTO A RESIDENTIAL STREET. PARTS FROM THE AIRCRAFT WERE FOUND SOME DISTANCE FROM THE ACCIDENT SITE. THE PROPELLER ALONG WITH THE SEVERED CRANKSHAFT FLANGE WERE FOUND STILL BOLTED TOGETHER LESS PART OF ONE PROPELLER BLADE. METALLURGICAL EXAMINATION REVEALED THAT A BLADE HAD FAILED MIDSPAN DUE TO FATIGUE. THE PROPELLER WAS BEING OPERATED ABOVE THE DESIGN RPM RED LINE OF 2,700. ADDITIONALLY, THE PROPELLER WAS BEING SUBJECTED TO GYROSCOPIC AEROBATIC LOADS. AN RPM RESTRICTION FOR THE PROPELLER MANDATED BY AN AIRWORTHINESS DIRECTIVE WAS NOT PLACARDED ON THE INSTRUMENT PANEL PER THE AD. THE ENGINE WAS DESIGNED FOR A TYPE CERTIFICATED HELICOPTER APPLICATION AND WAS APPROVED FOR A 3,200 RPM RED LINE.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.