CHI01LA147 · Cessna 150H

The airplane was destroyed when it impacted trees and terrain after a loss of control while maneuvering. The pilot said that he and his passenger were flying near his house at 800 feet above ground level so that the passenger could photograph the residence. The pilot said that he reduced airspeed and lowered 10-15 degrees of flaps, keeping the airspeed at the upper end of the flap operating range. The pilot stated that he executed a turn to the left. The pilot stated that when he began the left turn, he heard a, "loud pop in the left wing." He said that the control yoke was, "jerked out of [his] hand to the full left stop." The pilot said that the airplane continued to roll to the left even with full right aileron input. He stated that he lowered the flaps in an effort to, "slow [the airplane] down a little and therefore lessen the impact. However, all this did was intensify the roll." The airplane subsequently impacted trees and terrain. The flap control system was examined and a break in the flap control cable was observed. The broken flap cable and the right hand inboard pulley and bracket assembly were retained for further examination. No other anomalies were found. The broken flap cable, flap pulley, and pulley bracket were examined at the National Transportation Safety Board's Materials Laboratory in Washington, D.C. The cable break contained signatures consistent with overstress failure. The pulley bracket had a crescent wear mark adjacent to but outside of the cotter pin intended to retain the cable in the pulley groove. The wear mark was covered with a black residue and its appearance was not fresh. No wear was observed on the cotter pin.

Verbatim NTSB analysis and probable cause from the NTSB dataset