PORTLAND, Mo. • Travelers along state Highway 94 on a recent Friday morning may have noticed a small yellow and white helicopter hovering above a thicket of trees just south of the road.
That's a curious enough sight by itself. But even weirder is a system of 10 spinning circular blades suspended from the belly of the chopper by a 90-foot boom.
The giant flying saw looks like a sinister war machine, similar to the one that slices through James Bond's BMW in the 1999 movie, “The World is Not Enough." But it’s actually a tool deployed by Ameren Missouri to help keep the utility's 33,000-mile power distribution system free and clear of tree limbs.
Trees and limbs can cause big problems for electric utilities and their customers. More than 2 million homes and businesses were left powerless after strong storms swept through the eastern United States over the weekend. In all, parts of 10 states and Washington, D.C. were affected by the storms with some utility customers left in the dark for days amid a crippling heat wave.
Ameren Missouri, which dispatched crews to help with power restoration efforts in Chicago, faced its own problems with storm-related outages several years ago. The utility will spend $53 million on tree trimming this year and cut along 4,000 miles of circuit each year as required by state regulations. Most of it is done by ground crews. The aerial saw is used only for only the toughest 1 percent of the work.
“We use this in some real rugged, remote terrain where we can’t get our equipment in,” said Tom Beerman, Ameren Missouri's manager of forestry.
On this day, helicopter pilot Will Nesbit is trimming only about 2 miles of circuit, including a short stretch of power line just south of state Highway 94 near the Katy Trail. The wooded area is just off a private gravel road owned by Ameren. But a steep embankment and nearby creek make access difficult.
Before the day’s flight, Nesbit studied a large map of the area with circuits he’s going to trim highlighted in pink. Throughout his flight he stays in radio contact with two men who follow below on an all-terrain vehicle. Among other responsibilities, the ground crew scouts any unforeseen obstacles, such as a telephone line.
The tiny helicopter buzzes loudly as it clears the tree tops, sounding something like the millions of cicadas that invaded the St. Louis area last spring. As Nesbit budges the chopper forward, learning out of the cockpit, the massive 22-foot saw dangling below effortlessly sheers off large limbs. Nesbit works top to bottom on the trees.
Within minutes, a half-mile stretch of right-of-way is cleared.
“What he did right there, if you did that with a climbing crew, it’s a day’s work,” Beerman said.
Nesbit, 35, has spent six years as a pilot for Aerial Solutions Inc., a Tabor City, N.C.-based company that claims to have pioneered aerial tree trimming. Most of the work is done for electric utilities, with some trimming to clear oil and gas pipeline rights of way. The company has worked for various Ameren utilities for years.
If flying a small helicopter seems like challenge enough, Nesbit said the task becomes far more challenging with hundreds of pounds of whirring blade swinging below him like a pendulum.
“The wind and so forth affects (the saw) and it kicks off of trees. And when it hits limbs it pushes on it and pulls on it,” he said. “You learn to anticipate what it’s going to do. Of course, we do mess up once in a while and hit the tree trunk and you will feel that,” Nesbit said. “You’ll get a jolt.”
Nesbit has learned as well as anyone in the utility industry the value of tree trimming when it comes to maintaining the nation's power grid. It's also part of the business that gets little attention until something goes wrong.
St. Louis was spared damage from the storms causing trouble in areas to the east, but more than 600,000 Ameren Missouri customers were left without power during the storms of July 2006. Some went as long as nine days in the dark. Those outages and ice storms the following fall and winter triggered a harsh backlash and prompted regulators to require more frequent tree trimming.
Still, little of it is done by air. Aerial Solutions will cut about 35 miles with its helicopters this year, and only in rural areas. And the choppers can fly only when the weather cooperates.
While storms and high winds make it perilous for any pilot, the job is more dangerous when towing a massive saw near high-voltage power lines. And except when tree limbs are overhanging a line, Ameren doesn't de-energize its circuits while Nesbit is working.
Nesbit, who now lives in Lincoln County, Mo., said he won’t go up when there’s a threat of thunderstorms or gusty winds, which can whip the giant saw in directions he doesn’t want to go.
But caution turns to confidence when he's asked about his accuracy and ability to place the giant saw where he wants to.
Grinning, he said he could guide the blades "back in the same saw cut."
PREVIOUS MAJOR STORMS
Ameren’s service area dodged the major storms last week that severed power to more than 2 million homes and businesses across 10 states. But it was only six years ago that the first of a trio of storms walloped St. Louis metro area, frustrating residents and politicians and triggering investigations by regulators in Missouri and Illinois.