Flight Details
A certified flight instructor and a student pilot were conducting training on takeoffs and landings to confined areas. The student pilot performed a maximum performance takeoff from a confined area, reaching an altitude of approximately 10 feet above the trees.
Sequence of Events
During the transition to forward flight, the low rotor RPM horn sounded, and the helicopter began to settle toward the trees. The instructor applied full throttle and forward cyclic. Despite these inputs, the helicopter continued to settle, and the rotor RPM continued to decay. The instructor then leveled the helicopter and applied full collective. Shortly thereafter, the main rotor blades contacted trees. The helicopter settled into the trees and came to rest in a nose-down attitude.
Instructor Recommendations
The instructor reported that the accident was not preceded by any mechanical malfunctions. The calculated density altitude at the time of the accident was 3,500 feet. In response to the event, the instructor recommended limiting maximum performance takeoffs to large confined areas when operating above 3,000 feet density altitude.