Accident Sequence
The helicopter was parked on a west-facing urban heliport situated on the leeward side of tall buildings that blocked westerly winds of 15 knots gusting to 23 knots. The pilot executed a rearward takeoff in calm winds, with the helicopter slightly above its maximum gross weight. After clearing the heliport and while out of ground effect, the pilot performed a right pedal turn to initiate a north departure over the water and lowered the nose to accelerate. At that moment, the helicopter encountered a left quartering tailwind that had previously been blocked by the tall buildings. The helicopter began to settle and subsequently contacted the water.
During the right pedal turn to transition to forward flight, the pilot heard an audible degradation of rotor rpm and observed the N1 indication in the yellow range.
Weight and Performance
In interviews, neither pilot could articulate the maximum allowable gross weight for the environmental conditions; each only stated the helicopter was "good" for the takeoff. According to performance data, the maximum gross weight for takeoff was 11,700 pounds, but the data did not provide a means for calculating power margins. Prior to flying to the heliport on the day of the accident, the pilots had the helicopter fueled to capacity, basing that decision on an expected pickup of five passengers instead of the six who actually boarded. Despite being aware of the additional passenger, the pilot attempted the departure without conducting any additional performance planning.
Post-Accident Examination
Before contacting the water, the crew experienced uncommanded pitch and roll oscillations and high levels of vibration consistent with settling with power. Examination of the wreckage, post-accident engine runs, and testing of the digital engine control units revealed no preimpact anomalies.