Piper PA 34-200 N56213 accident near Umatilla, Florida

Probable cause

Maintenance personnel ‘s failure to complete and verify the proper installation of the main landing gear (MLG) torque links’ attachment hardware, which resulted in the right MLG torque link disconnecting and the pilot’s subsequent inability to maintain directional control during the landing roll.

NTSB analysis

The pilot receiving instruction and the flight instructor were conducting an instructional flight. During the approach to the destination airport, the pilot receiving instruction lowered the landing gear, and the instructor confirmed that the down-and-locked indications were all green. After touchdown and during the landing roll, the airplane suddenly entered an uncommanded and violent right swerve, which the pilot receiving instruction could not correct with full left brake, rudder, and aileron inputs. Subsequently, the airplane departed the runway and impacted a drainage ditch.

Postaccident examination of the airplane revealed that the upper and lower torque links of the right main landing gear (MLG) were undamaged and not attached; the attachment hardware was not in place nor recovered. Examination of the left MLG revealed that the upper and lower torque links remained connected, but a cotter pin was not found installed through the castellated nut and drilled bolt.

A review of the airplane's maintenance logbooks revealed that, about 1 month before the accident, the attachment hardware for the left and right torque links was replaced, which included the installation of cotter pins. The mechanic who signed off the inspection stated that, during subsequent maintenance, both torque links' cotter pins were removed and that, although the attachment hardware at both torque links was subsequently tightened, neither of the torque link's cotter pins were installed before the airplane was approved for return to service. Therefore, it is likely that the right MLG torque link attachment hardware loosened over time due to the lack of a cotter pin and eventually separated from the airplane, which resulted in the torque link becoming disconnected and led to the pilot's subsequent inability to maintain directional control during landing.

Text from the NTSB. Open the NTSB docket for ERA18LA178 for the full record.