Officials from Pittsburgh-Butler Regional Airport are notifying county residents that they may see two low-flying helicopters in various areas within Butler County through the end of July.

The aircraft will be performing contract work — surveying pipelines and power lines — for utility companies, said Ike Kelly, the manager of Pittsburgh-Butler Regional Airport.

The helicopter surveying pipelines in the county will be flying at altitudes of 100 or 200 feet, Kelly said, and hovering on occasion as workers search for evidence of ground disturbance or discoloration.

The helicopter patrolling along power lines will be outfitted with 10 large, circular saw blades suspended beneath the aircraft, Kelly said, and will be trimming tree limbs that are growing too close to the lines.

He advised people to keep clear of both aircraft as they perform their work. No daily schedule for the helicopters' flight is available, but Kelly said both aircraft would likely be operating in northern and eastern Butler County through the end of July.