Nose Gear Collapse Leads to Fuselage Penetration and Smoke in Cabin (G-BXAR)

Incident

Following a normal touchdown, the fracture of the nose landing gear main fitting allowed the nose gear to collapse rearwards and penetrate the lower fuselage. This caused significant damage to the equipment bay and the battery to become disconnected. The penetration of the fuselage allowed smoke and fumes produced by the consequent release of hydraulic fluid to enter the cockpit and passenger cabin. With the battery disconnected and after the engines were shut down, all power to the aircraft PA systems was lost and the remote cockpit door release mechanism became inoperative. No pre-accident defects were identified with the manual cockpit door release mechanism or the PA system.

Investigation Findings

The investigation determined that the nose landing gear main fitting failed following the formation of multiple fatigue cracks within the upper section of the inner bore, originating at the base of machining grooves in the bore surface. These cracks had formed because the improved surface finish, introduced by Service Bulletin 146-32-150, had not been properly embodied at a previous overhaul by Messier Services Inc, despite their overhaul records showing its incorporation. The operator had been in full compliance with the Service Bulletin relating to regular inspection of the main fitting, and embodiment of SB 146-32-150 at overhaul removed the requirement for these inspections by the operator.