What happened
On December 17, 2014, an EC 225 LP helicopter, registration PR-BGR, was performing a passenger transport flight between the P-35 and P-50 offshore platforms in Rio de Janeiro, Brazil. While hovering at approximately 7 feet above the helideck of the P-35 platform during the takeoff phase, the crew experienced an unusual noise accompanied by vibrations and aircraft instability.
In response to the disturbance, the pilot flying decided to abort the takeoff and immediately commanded a return to the helideck. This maneuver resulted in an abrupt touchdown, classified as an abnormal runway contact (hard landing). The impact caused substantial damage to the aircraft's tail cone and light damage to the lower fuselage. Despite the impact, all 17 persons on board—comprising three crewmembers and fourteen passengers—remained unharmed.
The investigation
CENIPA, with the participation of the French BEA, analyzed the flight data and cockpit voice recorder (CVR). The CVR confirmed a short-duration "popping" noise lasting less than one second, coinciding with a 2% variation in engine power (Nr).
Technical examinations of the engines by the manufacturer revealed no mechanical failure. While light erosion and the presence of salt and dust were noted in the compressor, the engines were within acceptable operating standards. The investigation focused on the "popping" phenomenon, which involves the reabsorption of hot engine exhaust gases into the intake. At the time of the accident, the aircraft's flight manual lacked specific procedures or alerts regarding this phenomenon, which is most prevalent during hovering or in high ambient temperatures.
Findings
- Inappropriate control inputs: The pilot's immediate command to land following the noise led to an abrupt and forceful contact with the helideck.
- Lack of instructional guidance: The flight manual did not contain specific procedures or warnings regarding the "popping" phenomenon, leaving the crew without the necessary training to recognize or mitigate the event.
- Absence of operational procedures: The lack of documented mitigation strategies in the support systems prevented the crew from managing the transient power loss effectively.