Cub Crafters PA18-150 N143CC accident near Edgewater, Florida

Probable cause

Maintenance personnel’s failure to detect the worn aileron cable during the most recent inspections, which resulted in the separation of the aileron control cable and a subsequent loss of airplane control during landing.

NTSB analysis

The pilot completed a banner towing flight and was landing when the accident occurred. When the airplane was about 20 to 30 ft above the runway, the pilot reported that he heard a loud snap and he quickly realized he lost aileron control. The pilot attempted to land using the rudder and the elevator; however, the airplane veered to the right of the runway and impacted a hangar, resulting in substantial damage to the wings and fuselage.

A postaccident examination of the airplane revealed that there was a break in the left aileron direct control cable in the vicinity of the lower left fuselage direct aileron pulley. The fractured cable had a thick coating of dirt, oil, and grease-like substance. The aileron direct cable also displayed significant corrosion in multiple locations. After cleaning the cable, the cable displayed significant wear on both ends of the break. Examination of the lower left fuselage direct aileron pulley revealed that the pulley would bind during rotation, and the bushing and bolt displayed corrosion and a buildup of debris.

It is likely that during aileron operation, the pulley would not rotate and that the corroded left aileron direct cable would rub against the pulley, accelerating cable wear. This resulted in the cable shedding material and becoming weaker, until it was unable to sustain the stresses of normal operation and fractured from tensile overstress. It is likely that the overstress fracture occurred during the landing, which is consistent with the right turn that the pilot experienced.

According to maintenance records, the airplane had three 100-hour inspections during the 6 months before the accident. The most recent inspection was about 67.7 hours before the accident. According to the inspection checklist, the aileron control cable and pulley should have been inspected. Had the cable and pulley been properly inspected they would have been found unairworthy due to their respective conditions. Based on this information, it is likely that maintenance personnel overlooked the corrosion and wear on the aileron control cable and the binding pulley during the most recent inspections.

Text from the NTSB. Open the NTSB docket for ERA24LA128 for the full record.