Dominion Aviation Services Beech C90A accident

During the downwind leg of the traffic pattern at the destination airport, the pilots lowered the landing gear. The pilot then noticed that the right main landing gear (MLG) was not down and locked in position for landing. The flight crew made multiple attempts to get a down-and-locked indication without success, so the pilot decided to abort the landing and divert to another airport with longer runways. After executing the manual gear extension checklist, the flight crew made a low pass at the diversion airport, and the air traffic controller in the control tower advised that the landing gear appeared to be in the down position. During the landing, the touchdown was normal, and the airplane slowed normally; however, as the airplane exited the runway, the right MLG collapsed. Examination of the wreckage revealed that the right wing, right nacelle, and right wheel well had received substantial damage and that the right MLG, after collapsing, had punctured the right nacelle fuel tank.

The right MLG bearing actuator support bracket was made of aluminum. Examination of the right MLG revealed that the right MLG bearing actuator support bracket was broken and had separated from its mounting position. Multiple cracks in the bracket were visible, and, at the microscopic level, the cracks had shiny surfaces indicative of abrasion, and overload regions with a cloudy appearance. Essentially, with each cycle, whether it was with extension of the landing gear, retraction of the landing gear, or landing itself, the cracks were subjected to loading which caused them to continue to propagate until the entire assembly reached a point at which structural integrity was no longer present to hold the landing gear actuator.

In December 2003, the airplane manufacturer issued a mandatory service bulletin to replace the right and left aluminum MLG bearing actuator support brackets with steel brackets and specified that the replacement of the brackets be accomplished "as soon as possible," but "no later than the next scheduled inspection, the next 200 flight hours or 24 months." The airplane manufacturer also requested that the Federal Aviation Administration (FAA) issue an Airworthiness Directive (AD) based on the service bulletin. However, the FAA did not find an "unsafe condition" and did not issue an AD, which would have made compliance with the service bulleting mandatory.

Review of the airplane's maintenance records confirmed that the airplane owner and the operator had not had the new steel brackets installed. Further, the FAA has not issued an AD for the MLG bearing actuator support brackets.

Verbatim NTSB analysis and probable cause from the NTSB dataset