PALM BAY, Fla. — The National Transportation Safety Board has released a preliminary report on the Sept. 6 helicopter crash in Palm Bay that killed three people.
Evidence indicates the helicopter's main and tail rotors may not have been spinning fast enough to keep the aircraft in the air at the time of the crash, the report said.
The crash happened at about 1:40 p.m. as the helicopter flew about 10 miles southwest of Melbourne International Airport, the NTSB said.
The crash happened about 16 minutes after the helicopter took off from the airport, the report said.
According to the NTSB, the helicopter’s operator, Illinois-based AAR Corp., had recently replaced the vehicle’s fore/aft pitch servo and was performing a functional check flight at the time of the crash.
Witnesses recorded the helicopter performing maneuvers near the accident site about 100 feet in the air, but none saw the crash, the report said.
The Sikorsky S-61R, built in 1974, was performing maximum performance maneuvers at its maximum gross weight of nearly 20,000 pounds at the time of the crash, the NTSB report said.
When found, the helicopter was upright with no debris path, the report said.
On impact, the helicopter caught fire and destroyed the cockpit and cabin, killing the pilot, co-pilot and a maintenance worker.
Investigators found that “the main and tail rotor blades exhibited signatures consistent with low rotational energy.”
According to information from the Federal Aviation Administration, losing rotational energy during flight is a dangerous, possibly fatal problem.
"Under certain conditions of high weight, high temperature, or high density altitude, a pilot may get into a low rotor rpm situation," an FAA flight handbook said. "Although the pilot is using maximum throttle, the rotor rpm is low and the lifting power of the main rotor blades is greatly diminished."
Because the tail rotor’s rpms are linked to the main rotor, a pilot could also lose directional control of the aircraft, the FAA said.
Complete loss of control of the helicopter in this situation can happen in as little as two seconds, the FAA handbook said.
“Rotor rpm is life!” it said.
The investigation into the crash is ongoing. The NTSB has not said when the final report will be issued.
The cockpit voice recorder was recovered from the wreckage and was being examined at the NTSB Vehicle Recorder Laboratory in Washington, D.C.
Cox Media Group
