Piper PA 18-150 N4393Z accident near Murphy, Idaho

Probable cause

Failure of the left aileron control cable that resulted in a loss of aircraft control during takeoff. Contributing to the accident was inadequate maintenance inspections to the aileron cable connections.

NTSB analysis

The flight of two airplanes landed at a dirt airstrip for a short break after flying in the area to spot elk. The passenger in the accident airplane recalled that during takeoff, the airplane's nose snapped to the right and then pointed toward the ground. The pilot in the other airplane (which had not yet departed) observed the accident airplane take off and reported that when it was about 150 ft above the ground, the right wing dropped and simultaneously he heard the accident pilot say "whoa" over the radio. The airplane's nose continued to drop, and the airplane impacted the ground in a nose-low, near-vertical attitude.

Examination of the airplane revealed that the left aileron control cable was separated from the eye fitting and thimble on the left aileron control cable turnbuckle. Further, the outboard left aileron control cable and the inboard right aileron control cable were improperly crimped. The improper crimping allowed the left aileron cable to pull through the swaged sleeve. As a result, the separation of the cable would have allowed the balance cable to become slack and the pilot would not have been able to control the roll of the airplane.

Examination of maintenance records revealed that 20 years before the accident, the left wing was rebuilt and reskinned and the flap and aileron hardware were replaced. The entry did not specifically mention that the control cables were replaced. Additionally, 10 years before the accident, the aileron balance cable and rudder cables were tightened. The airplane received an annual inspection every year, during which no discrepancies were noted with the flight control systems.

Text from the NTSB. Open the NTSB docket for WPR18FA026 for the full record.