Cessna 305 N65070 accident near Mokuleia, Hawaii

Probable cause

A separation of the left rudder cable due to inadequate maintenance, which resulted in an in-flight loss of control and impact with terrain.

NTSB analysis

The flight instructor was providing familiarization training to the airline transport pilot in the tailwheel-equipped airplane. Witnesses saw the airplane land hard; the pilots shut down the engine on the runway, the instructor got out and inspected the airplane, then boarded the airplane again and the pilots subsequently departed. The witnesses stated that, upon becoming airborne, the airplane entered a significant right yaw over the runway. The airplane continued to the right and subsequently impacted terrain about 1,000 ft from the runway.

Examination of the engine revealed no anomalies that would have precluded normal operation. Examination of the airframe revealed that the left rudder cable was separated at the rudder pulley area behind the rear seat floor and displayed a combination of severely frayed and fractured strands with tension overload signatures. There was evidence of cable abrasions and rubbing in the area of the pulley bracket. A detailed examination of the cable fractures revealed that only 16 of the 133 total wires that comprised the cable were intact before they failed in overload, resulting in cable separation. The remainder of the cable strand wires were either degraded, shortened, or bent, indicative of abnormal cable contact and abrasion. Although the aileron and elevator control cables were continuous or displayed indications of overload separation due to impact, all of the cables exhibited areas of fraying and extensive wear.

The most recent documented maintenance was a 100-hour inspection completed 5 months before the accident. The mechanic who had been responsible for maintaining the airplane for the previous 2 years stated that he cleaned, inspected, and lubricated the flight control cables during the inspection; however, the debris in the under-floor compartment, excessive black grease deposits, significant wear and fractured wires of each control cable were indicative of wear that had occurred over a period of time that should have been observed and rectified during previous inspections.

Based on witness statements and examination of the wreckage, the pilots experienced a loss of yaw control after takeoff due to an overload separation of the left rudder cable and were unable to regain adequate control to land safely. Although when the separation occurred could not be determined, it is possible that the hard landing just before the accident takeoff may have caused the already degraded rudder cable to be displaced and encounter excessive stress loads in the pulley area.

Text from the NTSB. Open the NTSB docket for ANC20FA024 for the full record.