Moments after the pilot lifted the Bell 206 JetRanger into a hover on a flight many years ago, I choked back a gasp and found myself almost frozen, unable to key the intercom mic button as a spiderweb of powerlines suddenly manifested themselves in front of the helicopter. All I had time to do was quickly point out the front windshield at the power lines, which neither of us had seen when we landed nor during the two hours we had hung around waiting for our passenger to return in a relatively remote location next to a river. The pilot instantly grasped what I was trying to show him and quickly pivoted away from the powerlines and climbed away. When our hearts stopped hammering, we talked about the disaster that had nearly happened.
Today our helicopter would, hopefully, have been equipped with some modern technology, such as Safe Flight Instrument’s Powerline Detector. During this year’s NBAA Convention, Safe Flight (Booth 1416) gave demonstration rides in a Bell 206 equipped with its new dual frequency powerline detection system (DPDS). Andrew Hayden, owner of Yalesville, Conn.-based Air Ocean Aviation and a frequent flyer for Safe Flight technology testing and demonstration flights, took me flying before the start of the NBAA show to demonstrate the simplicity and utility of the DPDS.
We took off from the busy Peabody Heliport on International Drive last Thursday morning, and immediately I could see the benefit of the DPDS. The system is extremely simple, and what is new is that it can detect powerlines emitting at both 50 Hz (international) and 60 Hz (U.S.). The system consists of a low-frequency receiver, which is mounted on the aft avionics shelf and connected to a simple wire antenna, plus a cockpit switch/display. The cockpit display includes a green power light, a lighted switch labeled with a red “WARN” and yellow “MUTE” and a rotary sensitivity adjustor.
When the receiver detects a live powerline, the red WARN lights up, and the pilot will hear a Geiger counter-like clicking sound in the headphones. The clicking speeds up and slows down depending on how close the helicopter is and how fast it is approaching the powerlines. Rapidly increasing clicks mean danger. The sensitivity knob allows the pilot to dial out nuisance warnings if, for example, flying powerline patrol duties or landing and taking off in a heavily industrialized area with many emitting lines in all directions.
Hayden flew us at about 500 feet to about four miles northwest of Kissimmee Airport where we crossed and re-crossed a large set of transmission lines. The audible clicking was just like a Doppler effect, where the click rate rose and fell as we flew closer and further from the lines. The WARN light illuminates even if the sensitivity is turned way down, and it goes dark only when no lines are detected. Hayden showed me how hard it is to see power lines when flying into the sun, and this is where the Safe Flight DPDS really shines. “I can’t see [the powerlines], but it’s screaming at me,” Hayden said. “The simplicity of the system is wonderful for the pilot.”
The DPDS is FAA certified on the Airbus SA341 Gazelle and Bell 206 and EASA certified on the Airbus AS350, AS355 and BK117 models. Australia’s CASA has approved the system for the EC145, BK117, Bell 206 and AgustaWestland AW139. It has also been installed under field approvals.