What happened
On April 28, 2016, an S-76A helicopter, registration PR-EMR, was conducting an offshore passenger transport flight from Macaé to the SS-62 Maritime Unit in the Campos Basin. The aircraft was carrying two pilots and nine passengers. Approximately 20 minutes into the flight, the crew received a right-engine fire warning.
Following the alarm, the crew shut down the right engine and initiated a return to Bartolomeu Lisandro Aerodrome. During the single-engine return flight, the crew descended from 4,500 ft to 500 ft ASL. As the aircraft approached the coastline, the crew struggled to maintain level flight. Upon reaching an altitude of approximately 200 ft, the crew executed an emergency landing in an unprepared field roughly four nautical miles from the aerodrome. The aircraft sustained substantial damage to the landing gear, the fuel tank, and the junction between the cabin and the tail cone. All 11 occupants emerged uninjured.
The investigation
CENIPA's investigation focused on the cause of the fire warning and the subsequent flight management. Investigators examined the engine fire detection system, including the infrared detectors and wiring. While they found evidence of salt exposure, dust accumulation, and worn insulation on the wiring, laboratory tests at DCTA could not identify a specific failure or vulnerability that caused the inadvertable activation. The hypothesis that sunlight triggered the sensor was also dismissed.
The investigation also reviewed the operator's Standard Operating Procedures (MPO) and training programs. It was noted that the operator's emergency checklist was a translation of the manufacturer's manual and lacked a clear instruction to confirm the presence of fire (via smoke or odors) before shutting down the engine. Furthermore, the investigation found that the crew's training did not adequately cover engine failures during cruise flight or energy management during single-engine en-route operations.
Findings
- The crew's decision to descend to 500 ft and reduce speed to the Best Rate of Climb (BROC) speed reduced the safety margin for altitude and speed management during the emergency.
- The operator's procedures did not explicitly require the confirmation of fire before engine shutdown, unlike the manufacturer's recommendations.
- Training deficiencies existed regarding engine failure management during the cruise phase and single-engine en-route operations.
- Maintenance deficiencies were indicated by the presence of salt, dust, and worn insulation on the fire detection system wiring.
- The left engine remained capable of delivering maximum takeoff power and sustaining flight throughout the event.