The pilot and observer aboard a Baltimore police helicopter that crashed last week reported hearing a "thud" and a "rumble" moments before the crash, federal investigators said in a preliminary report released yesterday.
A final cause for the Aug. 12 crash that left two city officers injured has not been determined, but investigators with the National Transportation Safety Board (NTSB) are testing the engine to determine whether there was a mechanical failure.
Meanwhile, city police continued the grounding of the remaining four helicopters.
The $250,000 helicopter crashed about 7 p.m. in Easterwood Park in West Baltimore as it pursued a dirt bike that had collided with a police car and then sped away. Police said the craft was flying just above treetop level when "it made some type of strange noise" and went down.
The pilot, Officer Lawrence Lester, 49, one of the most experienced helicopter fliers on the force, and his observer, Officer John Smith, 37, suffered minor injuries. They have declined requests for interviews.
Police refused to comment on the crash yesterday, saying their investigation was continuing. Department officials have refused to release a transcript or tape of radio communications between dispatchers and the pilot.
Monday, federal investigators said the pilot reported losing power just before the crash. Yesterday, the NTSB released a three-page preliminary report that offers the most detailed version yet of what led to the accident.
The helicopter took off from Martin State Airport about 6 p.m. About an hour later, Officer Lester told investigators that he was "following a suspect on a dirt bike who was being pursued by police ground vehicles."
Police deny that police cruisers were chasing the bike, which is forbidden by departmental policy.
"According to the pilot, he was flying eastbound along Baker [Street] and then over Easterwood Park," the report says. "He attempted to fly ahead of the suspect, so he descended and turned south over the park.
"He then decided to regain altitude, at which time he heard or felt a vibration or thud," the report says. "The next thing he remembers was being on the ground."
The observer, Officer Smith, told investigators that the pilot "had lowered to just above treetop level over the park when [he] heard a 'rumble.' "