Commercial drones are pretty lazy. Think about it: They spend most of their time taking photos and videos, inspecting equipment and streaming the footage back to HQ, or performing automated mapping or scanning tasks with assorted sensors. No heavy lifting, no powerful flexing, no manual labor. When will these drones finally start pulling their weight?

Right now, in Puerto Rico, it turns out. There, hundreds of thousands of American citizens continue to suffer through power outages, which began when Hurricane Maria battered the island with 155 mph wind gusts last fall. As Puerto Rico struggles to come back online, today’s commercial drones are actually lifting power lines into place, to help the tireless crews on the ground there do their jobs faster and more safely.

North Carolina-based Duke Energy, which has had 200 volunteer workers in Puerto Rico since January 14, is using five drones operated by two licensed pilots to search for broken utility poles, downed power lines buried under vegetation, and to string new lines over rough or inaccessible terrain.

The drones are subbing in for a tedious, imprecise, dangerous, and usually very human process. Ordinarily, Duke Energy’s workers would trudge through the island’s tropical mountain forests—and its ravines and gorges—to find dropped power lines and attach the rediscovered ones to a light string and brass projectile. The workers would then use a gun to shoot the lines through the 1,000-foot gaps between utility poles. That’s a pretty exhausting task for lineman working 13-day shifts, from sunup to sundown.

Drones can find power lines faster, without risking twisted ankles. And they can deftly maneuver between poles to thread the slightly more robust cord up to the structures. Workers then attach a heavier woven nylon cord to that string, which hauls the actual conductor to the pole’s attachment point.

While the process saves considerable time and money—Duke Energy wouldn’t share dollar figures—drones are also appealing for their safety benefits. “We are extremely excited about the technology’s ability to reduce risks that our employees encounter every day, such as working at heights, around energized equipment, and in confined spaces,” says Jacob Velky, Duke Energy’s manager of unmanned aerial systems.

Duke Energy’s commercial quadcopters are Zoe models from AceCore Technologies, starting at $15,000. They can carry up to 26 pounds and fly for up to 40 minutes. Two of the company’s drones in Puerto Rico are equipped with cameras—they help scout paths for the lines and assess damage to existing power distribution networks. But to increase the payload, the three drones actually doing the stringing work don’t have cameras or sensors on board at all. Instead, linemen rely on radios to confirm the drones are in the right place before releasing their string.

Another challenge: the weather. Gauging the effects of wind and rain, plus finding good takeoff and drop locations, are particularly difficult in a tropical mountain region. “Every mission has a unique challenge,” Velky says.

Duke Energy has used drones for day-to-day operations for several years—about 30 of its employees are trained and licensed to fly them. But the company expects demand for the drones’ services to only increase. “Although what we have encountered in Puerto Rico will likely be different than the US mainland, deployment on power transmission assets will continue to be a focus,” Velky says.

Workers will be stringing power distribution lines in Puerto Rico for at least the next few months. So the drones will have plenty of opportunities to prove they’re not just the eyes and ears in a crisis but the muscle too.

Droning On