What happened
On March 27, 2013, a Bell 412 helicopter, registration PT-HUW, was conducting a cargo transport flight between two offshore platforms in the Campos Basin, Brazil. The flight originated from the FPSO Rio de Janeiro (9PCI) with the destination being the P-07 platform (9PSL). On board were two crewmembers and one passenger.
During the final approach to the P-07 helideck, the crew reported hearing an unusual noise followed by intense vibrations throughout the aircraft. Video footage from the platform helideck captured the aircraft performing a high pitch-up maneuver. In response to the mechanical instability, the crew aborted the landing attempt and initiated an emergency descent to ditch in the sea.
Upon contacting the water, the helicopter tilted to the right, causing the main rotor blades to strike the sea surface. Although the aircraft's emergency floats deployed successfully, allowing the helicopter to remain buoyant, the impact and subsequent recovery efforts resulted in the aircraft being destroyed. During the attempt to recover the wreckage, the section of the aircraft containing the main transmission and driveshaft separated from the fuselage and sank to a depth of 111 meters.
The investigation
CENIPA investigators examined the recovered components, which included the main rotor assembly, the main gearbox (MGB), and parts of the driveshaft. While the main rotor transmission appeared normal, investigators found rubbing marks on the coupling of the tail rotor drive quill and fractures on the teeth of the flexible coupling of the main driveshaft. However, because the majority of the wreckage remained submerged, it was impossible to determine if these mechanical failures occurred during flight or as a result of the water impact.
Meteorological data indicated that while conditions were generally favorable, visibility had deteriorated due to rain and cloud formations near the landing site at the time of the approach. The investigation also noted that the aircraft's pitch exceeded the limitations specified in the flight manual, though it could not be confirmed if this was an intentional maneuver or a result of the deteriorating visibility.
Findings
- Adverse meteorological conditions, which may have impaired the crew's situational awareness regarding their approach to the helideck.
- Piloting judgment, specifically regarding the potential for an inadequate assessment of speed and height parameters during the approach.
- The crew experienced intense vibrations and noise prior to the decision to ditch.
- The three occupants of the aircraft escaped the wreckage without assistance and were rescued by the platform's emergency team; none of the occupants sustained injuries.