On May 22, 1989, a Bell UH-1B (registration N508SC) operated by Precision Air Services, Inc. was involved in an aviation accident near Oldtown, MD. Investigators recorded the probable cause as: FAILURE OF THE PILOT TO SEE-AND-AVOID THE OBSTRUCTION (INADEQUATE VISUAL LOOKOUT). FACTORS RELATED TO THE ACCIDENT WERE: THE OBSTRUCTION (STATIC WIRES), AND THE LACK OF VISUAL CUES FOR THE PILOT TO DETECT THE WIRES. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter collided with two 3/8-inch shield cables atop a power line while spraying for gypsy moths over hilly terrain. The aircraft crashed on a hillside; no preimpact failure was found.
Incident Overview
A helicopter conducting aerial spraying operations for gypsy moth control collided with two 3/8-inch shield cables situated atop a power line. The incident occurred over hilly, wooded terrain near the boundary of the intended spray zone.
Sequence of Events
According to witnesses, spray was seen coming from the helicopter's spray booms at the time it struck the cables. Following the collision, the helicopter's nose rose upward and the aircraft rolled to the right before crashing onto the side of a hill.
Investigation Results
Investigators found no evidence of any preimpact part failure or mechanical malfunction in the helicopter. Additionally, the helicopter was not fitted with a wire cutter kit at the time of the accident.