Incident Overview
An emergency medical services (EMS) helicopter was en route transporting one pilot, two medical personnel, and a patient. The patient, a fugitive with a gunshot wound, was handcuffed to the stretcher. During the flight, the pilot reported a problem involving the patient and requested police assistance upon arrival at the hospital. The pilot then transmitted an expletive, after which radar contact with the aircraft was lost.
Wreckage and Breakup
Wreckage was found scattered over an area of approximately one mile. Evidence indicated an in-flight breakup, with main rotor contact marks on the cockpit and tail cone.
Investigation Findings
Examination revealed evidence of a swashplate bearing seizure. The pitch change link rods and rotational scissors were broken in the direction of main rotor rotation, and contact marks were found on the forward ears of the rotating swashplate lugs. Disassembly showed failure of the inner and outer race locks and spalling of the bearing races. A lack of grease was noted in the bearing, and the ball bearings were discolored blue. Wear marks on the ball bearings indicated scuffing; one ball bearing was fluted.
Maintenance History
The bearing assembly had accumulated 1.23 hours of operation since the last 100-hour inspection. Lubrication of the bearing was required every 400 hours, while company policy mandated lubrication at 100-hour intervals.
Probable Cause
The investigation did not explicitly state a probable cause for this accident.