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Atlas / NTSB / ANC19LA039

NTSB CAROL · Event

Event ANC19LA039

2019-07-22 Boise, Idaho, United States Airport · BOI None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

A ductile overstress fracture failure of the right main landing gear bell crank assembly pivot bolt, which resulted in a collapse of the right main landing gear.

Factual narrative

On July 22, 2019, about 1147 mountain daylight time, a Cessna 402B airplane, N7947Q, sustained substantial damage when it was involved in an accident near Boise, Idaho. The two pilots and the FAA observer were uninjured. The airplane was operated under Title 14 Code of Federal Regulations (CFR) Part 91, in accordance with a Part 135.297 instrument proficiency check and a Part 135.399 check airman observation flight. The first pilot, who was the operator's director of operations, reported that he was receiving an instrument proficiency check from the second pilot, the operator's chief pilot; with an FAA aviation safety inspector in the passenger cabin observing the check ride for the purposes of a check airman observation flight. The first pilot stated that, after completing a series of required flight maneuvers, they returned to the departure airport, and the airplane was subsequently cleared to land. During the landing approach, he selected the landing gear selector switch to the down position, which was followed by "three greens," indicating that the landing gear was down, locked, and safe for landing. He noted that all three occupants verified and verbally confirmed that the landing gear was "down and locked." The first pilot stated that, after an uneventful landing, the airplane continued down the runway as the airplane decelerated. When the pilot started a left turn to exit the runway, the right main landing gear collapsed, and the right wing impacted the ground, sustaining substantial damage. A postaccident examination of the landing gear system revealed that the right main landing gear assembly bell crank pivot bolt (p/n NAS464P4-26) had sheared and displayed features consistent with a ductile overstress fracture failure. Figure 1, from the applicable parts catalogue, depicts the main landing gear retraction linkage. The affected bolt from the accident airplane is labeled as #29. Figure 1. Cessna 402 Main Landing Gear Retraction Linkage Installation The pilot reported that, during the landing approach, he selected the landing gear selector switch to the down position, which was followed by "three greens," indicating that the landing gear was down, locked, and safe for landing. He noted that all three occupants verified and verbally confirmed that the landing gear was "down and locked." The airplane landed uneventfully, but as the pilot started a left turn onto the taxiway, the right main landing gear collapsed, and the right wing struck the ground, sustaining substantial damage. A postaccident examination of the landing gear system revealed that the right main landing gear assembly bell crank pivot bolt had sheared and displayed features consistent with a ductile overstress fracture from shear loading. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12

NTSB Findings

Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).

  • Aircraft-Aircraft systems-Landing gear system-Main landing gear attach sec-Failure

Verbatim from NTSB's published report. Source file NTSB_2019_ANC19LA039.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

Related research

What the literature says.

Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.

Browse the full corpus — academia portal ↗