Cessna 336 N3835U accident near Porterville, California

Probable cause

Maintenance personnel’s failure to properly secure the elevator control assembly hardware, which resulted in an in-flight disconnection of the elevator and elevator counterweight and the pilot’s inability to maintain pitch control.

NTSB analysis

Shortly after takeoff, the pilot transmitted over the radio that he had lost “almost all pitch control,” but thought that he would be able to return and land at the departure airport. Automatic Dependent Surveillance Broadcast (ADS-B) data showed that the airplane climbed to about 1,550 ft mean sea level (msl) before entering a descending right 180° turn toward the departure airport. The airplane leveled off about 1,000 ft msl and continued toward the airport. About two minutes later, the airplane entered a descent from 975 ft that continued to ground contact.

Witnesses reported that they observed the airplane flying at low altitude when it suddenly descended into the ground in a steep, nose-low, wings-level attitude.

Postaccident examination of the wreckage revealed that the bolt, castellated nut, and cotter pin that connected the balance weight to the elevator control assembly were missing. Soot was observed within the area of both connection points, including where the bolt and washer would have been installed, consistent with the hardware not being installed at the time of the accident. It is likely that the bolt separated while in flight, resulting in a loss of elevator pitch control. The missing bolt, nut, washer, and cotter pin were not located.

The airplane was painted and returned to service about 28 days before the accident, which included removal and reinstallation of all the flight controls. It could not be determined if the securing hardware (nut and cotter pin) were installed at the time of the reinstallation of the elevator.

Toxicology testing of the pilot revealed the presence of ethanol in liver tissue; however, the detected ethanol likely was from postmortem production. Thus, it is unlikely that ethanol contributed to the accident.

Text from the NTSB. Open the NTSB docket for WPR22FA216 for the full record.