What happened
On December 1, 2002, a Robinson R-44, registration PT-YGK, was performing a charter flight for the Civil Police of the State of São Paulo. The flight was departing from the courtyard of an abandoned factory in the Ipiranga neighborhood of São Paulo.
During the takeoff roll, the pilot reported a loss of available power. As the aircraft reached the height of a nearby building's roof, the pilot attempted to override the governor to clear obstacles. This action resulted in a loss of power and a subsequent drop in main rotor RPM, triggering the low RPM warning horn. To avoid the structures ahead, the pilot initiated an autorotation and opted for a running landing on an open area of terrain. During the landing, the right skid struck a concrete slab, causing significant damage to the main rotor, transmission, and tail cone. The pilot and three passengers were uninjured.
The investigation
CENIPA's investigation focused on the environmental and operational conditions at the time of the accident. The aircraft was operating near its performance limits due to the high temperature (32°C) and weight (1,005kg). Investigators consulted the manufacturer, who noted that while the helicopter could hover out of ground effect under these conditions, taking off with a 17-knot tailwind is extremely dangerous because power requirements increase rapidly as the aircraft accelerates through zero airspeed.
Engine testing conducted on the power plant after the accident showed normal parameters, ruling out mechanical failure of the engine as a cause. The investigation also examined the pilot's decision-making process regarding the choice of the landing site and the lack of managerial oversight regarding operations at non-certified locations.
Findings
- The pilot failed to account for the 17-knot tailwind, which significantly compromised takeoff performance.
- The pilot's decision-making was flawed, as he did not adequately evaluate the terrain for a safe landing and chose a running landing instead of a vertical one.
- There was a lack of adequate managerial supervision, as the responsibility for evaluating the safety of the uncertified takeoff site rested solely with the pilot.
- The takeoff site lacked sufficient clearance from obstacles for a safe departure.
- The pilot's attempt to override the governor contributed to the loss of rotor RPM.