Chandler Field, Alexandria Airport
Aircraft Accident/Incident Report

Alexandria, Minnesota 56308
Friday, March 29, 2013 10:45 CDT

The pilot reported that, while on the downwind leg of the airport traffic pattern, he heard a loud noise during flap extension. The pilot initiated a climb and struggled to maintain roll control. He stated that he attempted to reduce the airplane’s rolling tendency by adjusting flap position. According to data from an onboard flight recording device, he briefly adjusted the flaps to the up position and then back to half. He then adjusted the flaps from half to full, and the airplane began to roll right due to flap asymmetry, eventually reaching 86 degrees of right bank. The airplane began to stall, and the pilot activated the airplane’s ballistic parachute recovery system. Subsequently, the airplane descended to the ground with the aid of the parachute and came to rest upright on a frozen lake. About 18 months before the accident flight, the airplane underwent maintenance to remove and replace both the left and right flaps. According to maintenance manual procedures, the mounting bolt and washer hardware were to be safety wired to the flap actuation fitting. However, during postaccident examinations, the right flap rod end was found disconnected from the right flap actuation fitting, and the connection hardware was missing. The mounting bolt and washer were found lying under the airplane; however, no safety wire was found. Therefore, the safety wire was most likely not installed when the right flap was reinstalled during maintenance. Although the mounting bolt and washer were likely tightened during the installation, they likely gradually became loose over time because of the missing safety wire, which led the right flap rod end to separate from the right flap actuation fitting during the flap extension on the accident flight. Since the time of the maintenance (211 hours of operation), annual, prebuy, and preflight inspections occurred, during which the lack of a safety wire went unnoticed.

The failure of maintenance personnel to install a safety wire during reinstallation of the right flap, which led to the separation of the right flap rod from the right flap actuation fitting during flap extension. Contributing to the accident were inadequate inspections of the right flap during subsequent annual, prebuy, and preflight inspections.