History of Flight
On November 3, 2017, about 0900 mountain daylight time, a Piper PA-18-150, registration N4393Z, was substantially damaged when it crashed near Murphy, Idaho. The pilot was fatally injured, and the passenger was seriously injured. The flight was conducted under 14 CFR Part 91 as a personal flight.
According to a witness, two airplanes departed Boise, Idaho, about 0730 to fly over the accident pilot's property to spot elk. After flying for about 1.5 hours, the airplanes landed because the passenger became airsick. Both airplanes remained on the ground for about 20 minutes before departing on the accident flight. The witness observed the accident airplane take off, establish a positive rate of climb, and when about 150 ft above ground, the right wing dropped while the pilot keyed the microphone and said "whoa." The nose continued to drop, and the airplane impacted the ground in a nose-low, near-vertical attitude.
The passenger stated that during the takeoff climb, the airplane's nose "snapped" to the right and was pointed to the ground. He thought the pilot added power as the engine noise got louder. The passenger did not recall hearing the pilot say anything during takeoff or the crash.
Aircraft Information
The airplane logbooks showed an entry on April 25, 1997, indicating the left wing was rebuilt with new spars and ribs, recovered with a polyfiber finish and Ceconite 101 fabric, and the left flap and aileron were replaced. An August 3, 2007, logbook entry noted the aileron balance cable and both rudder cables were tightened during the annual inspection.
The aileron control system used cables: a single cable assembly connecting cockpit control to each aileron, and a two-segment balance cable connecting left and right ailerons. Cables attached via turnbuckles with clevis and eye terminals. The eye terminal was formed by sliding a sleeve onto the cable, looping the cable around a thimble, inserting the cable end back through the sleeve, and compressing the sleeve. Proper compression is verified with a manufacturer's go/no-go gauge based on FAA specifications.
Wreckage and Impact Information
The airplane came to rest inverted about 1,750 ft from the south end of the airstrip. Both wings remained attached with uniform leading-to-trailing edge crush damage. The tail and empennage were connected and sustained minor damage.
The right aileron control system was intact except the crimped sleeve at the inboard eye end had an irregular pattern; only two or three required crimps were properly dimensioned. The left aileron control cable was separated from its turnbuckle at the aileron. The left aileron control cable sleeve was not recovered; the cable displayed a light-colored area where the sleeve would have been. The turnbuckle remained intact with lockwire in place.
The crimp at the inboard end of the left aileron control cable had an irregular pattern: widths not uniform, overlapped, and shallow. According to FAA Advisory Circular 43.13-1B, a 3-press sleeve is required for 1/8-inch cable. The inboard right aileron control cable also had an irregular crimp. When the go/no-go gauge was used, both irregular crimps did not fit into the designated slot (Oval M), indicating the crimp was not acceptable or airworthy.
Flight control continuity was established from tail to flight controls and out to both wings except for the left aileron control cable. The aileron balance cable was intact. No other flight control separations were identified.
The propeller assembly remained attached; the spinner was crushed. Both blades had S-bending, one blade had chordwise scratches, and both blades were bent aft with leading edge gouging and polishing.
The engine was manually rotated; valve train and mechanical continuity were established. Thumb compression was obtained at all cylinders. Magnetos produced spark. No preexisting conditions would have precluded normal operation. The carburetor had separated at the venturi; fuel in the gascolator was blue; the carburetor fuel inlet screen was free of debris. The engine examination revealed no mechanical failures or malfunctions that would have precluded normal operation.
Medical and Pathological Information
An autopsy performed by the Owyhee County coroner's office determined the cause of death as blunt force trauma. Toxicological testing by the FAA Forensic Sciences Laboratory was negative for tested drugs, carbon monoxide, and ethanol.