By Kevon Storie
Photos by Travis Weger
WAPA’s Strategic Roadmap 2024 identifies Business, Technology and Organizational Excellence as a critical pathway toward optimizing operational effectiveness. Using WAPA’s Aviation program to save thousands of dollars on transmission system inspections, maintenance and repairs while increasing safety for crews is excellence and effectiveness in action.
Two recent projects—one using a helicopter and one using an unmanned aerial system, or UAS—demonstrate the advantages and value of Aviation alternatives to ground transportation.
HEC offers efficiency, safety
Rocky Mountain Maintenance crews needed to replace 90 miles of stock bridge dampers with spiral vibration dampers in the rugged, desolate terrain near Dinosaur National Monument in northwestern Colorado. The wind moving on overhead power lines causes vibrations that destroy attachment hardware; the new spiral dampers dissipate the induced vibrations.
To make the replacements, the crews could choose to climb the structures, drive bucket trucks with lifts or lower a line worker from a helicopter—referred to as human external cargo or HEC—to the power line attachment points.
In addition to the avoided costs of about $640,000, the job was completed ahead of schedule. There were other advantages as well; HEC reduces workers’ exposure to live transmission equipment and requires minimal interference with right of way.
Learning to fly
WAPA’s helicopter pilots must train for several months to qualify to fly HEC operations, while maintenance crews require one to two days of training in the close cooperation aerial jobs require.
All of the communication is nonverbal, Aviation Manager Richard Westra noted, since the line worker is suspended in midair far below the helicopter.
“We communicate by helmet,” he said, displaying the broad-brimmed hardhat that line workers wear during HEC jobs. “They move their heads left to right to tell the pilot to lower them, and nodding up and down means ‘raise.’ No movement means hold steady.”
Line workers who haven’t worked on an HEC project for more than 90 days must take a refresher course beforehand.
“Once they are on the structure, though, they are just doing what they normally do,” said Westra.
A new way to inspect
Tower inspections are other maintenance tasks in which aerial technology can save time, money and even lives. Using a UAS, Rocky Mountain Maintenance crews took less than 13 hours to inspect 25 towers between Craig, Colorado, and Vernal, Utah, compared to the 25 hours line workers would have spent climbing each structure and performing the inspections.
“A UAS can complete a tower inspection in literally half the time it takes a line observer to do it,” said Westra. “It eliminates the need for a worker to climb the structure, which is physically demanding. It always increases safety when a worker can stay on the ground.”
The estimated cost to manually climb 25 structures was approximately $11,250, while the UAS inspections, including operational cost, was approximately $2,188. That represented more than $9,000 in avoided costs to do the same job, minus the physical risk to the crew.
Right vehicle for job
Unmanned aerial systems are still new tools for transmission maintenance and are used for visual inspections only. WAPA is working with the Federal Aviation Administration to develop best working practices for UAS.
Although the use of HEC has increased in the past few years, utilities have used helicopters since the 1960s for crew support, including landing workers on structures. HEC can accelerate the job schedule for projects that require lots of climbing, such as insulator replacement, hot-end hardware replacement, midspan repairs and tower modifications. The approach is also well suited to jobs in remote locations that require hours of driving to reach, in rough terrain where it would be difficult and dangerous to park and set up a truck and in rights of way where an extensive repair could tie up traffic.
Bucket trucks, however, are still the vehicles WAPA dispatches for most maintenance work.
“There are a lot of places where it still makes sense to use the trucks,” Westra acknowledged. “Safety always comes first at WAPA.”
Note: Storie is a technical writer who works under the Wyandotte Services contract.
Helicopter Pilot Rory Kirkendall looks down at a line worker who communicates
instructions via head movements.
Aviation assistance can result in reduced costs, increased
safety and shorter turnaround times on projects.
Last modified on September 12th, 2023