Incident
Shortly after an intermediate level-off at 13,000 feet, the flight crew heard a loud bang and felt the airplane shudder. The crew diverted to a nearby airport. During the landing roll, the engine's thrust reversers were deployed. The right engine thrust reverser deploy light illuminated, but the left engine thrust reverser deploy light did not illuminate.
Maintenance Findings
After landing, maintenance personnel found that the left engine lower thrust reverser door had been struck repeatedly by the top reverser door. An investigation revealed broken and bent thrust reverser linkages. Additionally, a pivot bolt, washers, castellated nut, and cotterpin associated with a driver linkage arm were missing.
Similar Issues on Other Aircraft
Two other company airplanes were found with a missing cotterpin from the pivot bolt. Examination of these assemblies revealed that the bolt end did not protrude beyond the nut's outer edge. As a result, the cotterpin could not fit through the hole in the bolt. The manufacturer's parts manual and maintenance manual text indicated that one countersunk washer should have been below the bolt head and one flat washer under the nut. However, the corresponding illustration in the maintenance manual showed an additional washer (2 washers) under the nut.