Accident Overview
A police helicopter was involved in a pursuit of a suspect traveling on a dirt bike. Ground units also participated in the chase. The pursuit proceeded eastbound into a park.
Pilot and Observer Accounts
According to the pilot, he attempted to fly ahead of the suspect. He reported descending and turning south. He then decided to regain altitude. At that time, he heard or felt a vibration or thud. The next thing he remembered was being on the ground inverted.
An observer aboard the helicopter stated that the pilot, in an unsuccessful attempt to get ahead of the suspect, descended to about treetop height. The pilot leveled the helicopter and then began to climb. The observer felt a vibration rumble through the helicopter, followed by ground impact.
Accident Site and Wreckage
Examination of the accident site revealed the helicopter came to rest on its left side. A separated 4-foot section of the tailboom was located about 125 feet away from the main wreckage.
Aircraft Examination
Examination of the aircraft did not disclose evidence of mechanical malfunction of the main rotor, tail rotor, drive system, flight controls, fuselage, or engine. The engine was tested and operated at 3,150 rpm for about 20 minutes at 25 inches of manifold pressure.
Examination of the tailboom fracture surface revealed evidence of overstress. No evidence of pre-existing cracking was noted.