Accident Details
On June 21, 2009, at approximately 0120 eastern daylight time, a Robinson R-22 Beta helicopter, registration N2306T, struck trees while executing an emergency autorotation in Delray Beach, Florida. The flight was operated as an instructional flight under 14 CFR Part 91 with an instrument flight rules flight plan filed. Night visual meteorological conditions prevailed at the time. The flight departed Palm Beach County Park Airport (LNA) in Lantana, Florida, at 0105 and was en route to Kendall-Tamiami Executive Airport (TMB) in Miami, Florida.
Pilot Statements
The certificated flight instructor (CFI) reported that after takeoff from LNA and opening the flight plan with Miami Center, while at 3,000 feet and an airspeed of 65–70 knots, he felt a low-frequency vibration throughout the helicopter. He described it as a lateral vibration, possibly from the tail rotor. He took control from the student, lowered the collective, and selected a landing area. He noticed the clutch light and one other light illuminated, though he could not recall its color or location. The vibration did not change with reduced power, and he did not attempt to add power. He confirmed no overspeed occurred and did not hear the low rotor RPM warning horn. During the approach, he saw wires and chose a spot near trees, where the helicopter contacted trees and the ground.
The student pilot stated that during a climb from 3,500 feet MSL to 4,000 feet MSL, they felt an airframe vibration that intensified until the instrument panel became unreadable. Both the rotor brake light and clutch light illuminated. The CFI took control and initiated an autorotation. During flare and touchdown, the low rotor RPM light and horn activated as the helicopter struck trees and rolled onto its right side.
Examination Findings
A Federal Aviation Administration (FAA) inspector examined the helicopter. The leading edges of the main rotor blades had no impact damage, and the blades were intact but bent. One pitch control rod was broken on impact. The main gearbox temperature tape indicated normal range. The tail rotor blades and gearbox showed no impact damage. The right side of the horizontal stabilizer was bent from ground contact. The tail section was broken and bent downward and left. The vibration dampener inside the tail cone was undamaged. Both main drive vee belts were off their pulleys. The forward belt left black residue on the pulley and shaft front side. The rear belt was broken in two and also had breaks in the center between the two V sections. Apart from the breaks, the belts showed no signs of deterioration or pre-existing visible damage.
A review of the helicopter's logbooks revealed no entries indicating when the drive vee belts were last replaced. The engine had been last overhauled 430.5 flight hours before the accident. Total time on the airframe at the time of the accident was 6,630.6 hours.