Gear Jamming Due to Missing Hinge Bolt on Approach

Casualties unknown • Kansas City, MO, US

A crew diverted after failing to extend the left gear, discovering a missing hinge bolt had jammed the mechanism during extension attempts.

What happened

During the final approach to Topeka, the flight crew encountered a critical mechanical failure when they were unable to lower the left main landing gear. Despite multiple unsuccessful attempts to cycle the system, the crew decided to divert to Kansas City for a safer environment. Upon arrival, after exhausting standard procedures without success, the pilots elected to perform a wheels-up landing to avoid further complications or potential structural damage from prolonged cycling.

The investigation

Post-accident examination revealed that the left main gear had become physically jammed within the wheel well. Specifically, the gear was trapped against the gear doors due to a missing aft hinge bolt on the left inboard gear door. This absence allowed the door to shift out of alignment just enough to obstruct the gear's extension path.

Maintenance records indicated that 17 days prior to the incident, company maintenance had identified a loose aft hinge during a preflight inspection. However, they were unable to retorque the bolt because the nutplate attachment rivets had been stripped. Consequently, this discrepancy was carried as a delayed repair item. The investigation highlighted that these specific parts require lubrication only before installation, and the entire assembly is notoriously difficult to inspect, remove, or service.

Findings

The manufacturer noted that attempting to "short cycle" the gear up to 18 times could eventually break open the gear doors, a method not widely disseminated to all operators. The combination of the missing bolt and the inability to perform immediate maintenance created a latent failure mode that ultimately resulted in the jamming event.

Safety message

This incident underscores the importance of addressing deferred maintenance items promptly, particularly those involving critical flight control or landing gear components. It also highlights the need for operators to be aware of specific manufacturer emergency procedures for gear extension failures.

Probable cause

The missing aft hinge bolt on the left inboard gear door, which allowed the gear door to shift and jam the gear during extension, compounded by the inability of maintenance to retorque the bolt due to stripped nutplate attachment rivets.

Frequently asked questions

What happened in the 1982-08-20 Swearingen SA226TC accident near Kansas City, MO?

A crew diverted after failing to extend the left gear, discovering a missing hinge bolt had jammed the mechanism during extension attempts.

What aircraft was involved and where did it happen?

The accident on 1982-08-20 involved a Swearingen SA226TC, registration N237AM, operated by Air Midwest, at Kansas City, MO.

What was the probable cause of the accident?

The missing aft hinge bolt on the left inboard gear door, which allowed the gear door to shift and jam the gear during extension, compounded by the inability of maintenance to retorque the bolt due to stripped nutplate attachment rivets.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20020917X03876. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

Loading the flight search…