What happened
On April 2, 2015, an EC1s5B1 helicopter, registration PP-LLS, was performing ground maneuvers at a helipad in Carapicuíba, São Paulo. The aircraft was taxiing from a parking spot toward a designated area to undergo a dynamic balancing of the main rotor following maintenance procedures on the tail rotor.
During the taxiing phase, the aircraft unexpectedly became airborne before reaching the intended helipad. After gaining altitude and departing the immediate area, the helicopter entered an uncontrolled descent, eventually striking two residential buildings approximately 1.27 NM from the departure point. The impact destroyed the aircraft and resulted in five fatalities, including the four crew members and one passenger.
The investigation
The investigation, conducted by CENIPA with participation from the French BEA, focused on the flight controls and maintenance records. Investigators examined the wreckage and found that the right-hand (RH) roll ball-type flexible control was not connected to the RH roll bellcrank prior to the flight.
Technical analysis of the aircraft's logs revealed discrepancies in maintenance documentation. While the aircraft's engine and airframe logbooks were out of date, having not been updated since June 2014, inspection sheets indicated a higher number of operational hours and cycles. The investigation also looked into the status of the main rotor assembly and the integrity of the servocontrols during the sequence of events.
Findings
- The unconnected RH roll ball-type flexible control was the primary factor leading to the loss of control.
- The aircraft's flight control system was compromised because the right-hand roll flexible control was not properly attached to the bellcrank before takeoff.
- Maintenance documentation for the airframe and engines was not current.
- There were inconsistencies between the hours recorded in the primary logbooks and the hours recorded in the maintenance inspection sheets.