What happened
On February 24, 2015, an Agusta AB139, registration PR-EFX, was conducting an offshore passenger transport flight from Macaé Aerodrome to the SS80 platform in the Bacia de Campos, Rio de Janeiro. The flight was carrying two crewmembers and ten passengers. During the en-route phase of the flight, the emergency window on the pilot's side door unexpectedly detached from the aircraft. The window was lost over the sea and was not recovered. The crew immediately initiated a return to the origin aerodrome and performed a normal landing. There were no fatalities or injuries among the twelve people on board, though the aircraft sustained light damage to the fuselage and door area caused by the impact of the detached window.
The investigation
CENIPA investigators examined the aircraft's maintenance history and the physical condition of the door frame. The investigation focused on the fact that the aircraft had recently undergone a general painting service, which required the disassembly and reassembly of the door and window. Investigators compared the window frame to the requirements set forth in Temporary Maintenance Instruction (TMI) 139-402.
During the field action, it was discovered that the painting process had covered an area of the window frame that was required to be free of paint to ensure the proper adhesion of the sealant. This discrepancy prevented the window from being properly secured to the structure. The investigation also noted a similar occurrence involving another AB139, registration PR-SEO, which had experienced a similar window detachment one month prior due to similar maintenance and sealant issues.
Findings
- Improper maintenance execution: The painting service failed to comply with TMI 139-402, as paint was applied to the window frame lip where it should have been removed to allow for correct sealant adhesion.
- Lack of specialized training: Technicians responsible for the maintenance and window replacement lacked specific