Incident Overview
A McDonnell Douglas MD-900 medevac helicopter was dispatched to a car accident at a location with high terrain and tall trees. The departure from the landing site occurred during dusk-to-dark night conditions.
Pre-Departure Information
Before landing, the pilot inquired about the presence of wires at the site and was informed by ground personnel that there were none. After landing, the pilot visually examined the landing zone and the planned departure route for wires and reportedly observed none.
Departure and Wire Strike
Due to the narrow canyon environment, the pilot executed a vertical climb during departure. While climbing, the helicopter struck unmarked transmission lines located approximately 150 feet above ground level.
Post-Strike Actions
Following the impact, the pilot assessed the helicopter and determined it remained controllable with no unusual flight characteristics. The pilot then decided to continue to the intended destination.
Damage
A post-flight examination identified crazing (cracking) of the windscreen and damage to four of the five main rotor blades. The blade damage necessitated major repair or replacement.