From Issue 3/2003, Aviation Safety Vortex (shameless plug)
21 January, 2002 AS350BA
Squamish, B.C.
TSB Occurrence No. A02P0017
The A-Star had just departed Squamish airport with a sling load of antennae on a long line with a remotely operated electric hook. The load was to be delivered to the top of Hospital Hill, about 6 NM SE. At approximately 800 ft, while over flying high voltage power lines, the load inadvertently released from the remote hook and fell into the wires. Company maintenance personnel inspected the installation and no defect was found. It is suspected that the electric release suffered electromagnetic interference from the proximity of the power line, and the company has replaced the release cable with ‘high impulse protected wire.’
This drives home the practice of never over flying people or property with a sling load. Last year we had nine reported events where the sling load didn’t make it to destination because of an inadvertent release. -Ed.