Incident Overview

Description
Air One flight 2843, a Boeing 737-400, experienced the loss of the left nose gear wheel upon departure from the Catania, Sicily, Italy. The flight proceeded to Rome’s Fiumicino Airport and landed with no further incident. PROBABLE CAUSE (translated from Italian): The accident was caused by the rupture of the front carriage leg axle, part of the assembly the inner cylinder PIN 65-46215-4, produced at the area of the left wheel swivel, due to a stress corrosion mechanism. This phenomenon of rupture has developed from a generalized corrosion phenomenon with the development of pitting occurred on the outer surface of the axle, in the area with the highest concentration of mechanical stress to which the part is subject. Both the stress-corrosion nature that led to the breakage and the generalised corrosion phenomenon that triggered it were not promptly removed during the maintenance operations (although regularly carried out on the component), since the damage has developed in an area not effectively controlled by the maintenance procedures at the time. The criticality of the Carrosion Prevention Task Card of NLG NP32-00-01, which did not require the removal of the spacer to observe the surface of the axle in the area with the greatest flexural load, therefore contributed to the event.
Primary Cause
Rupture of the front carriage leg axle, part of the assembly, due to a stress corrosion mechanism, resulting from generalized corrosion and pitting on the outer surface of the axle, exacerbated by high mechanical stress.Rupture of the front carriage leg axle, part of the assembly, due to a stress corrosion mechanism, resulting from generalized corrosion and pitting on the outer surface of the axle, exacerbated by high mechanical stress.Share on: