HILO, Hawai'i — The pilot and four passengers on a Big Island tour helicopter were injured yesterday after the helicopter made a "precautionary landing" and tipped over onto its left side in tall grass in a pasture near the Wailuku River outside of Hilo, police and fire officials said.

Police said none of the injuries appeared to be life-threatening, and that the pilot of the Tropical Helicopters' Hughes 500E was able to direct rescuers to the scene of the crash shortly before 2:50 p.m.

Ian Gregor, spokesman for the Federal Aviation Administration, said the helicopter developed engine trouble after the flight departed from Hilo Airport yesterday, prompting the pilot to make the precautionary landing six to seven miles from the airport.

The helicopter tipped over onto its side after the landing, and some of the people on board "might have received minor scratches," Gregor said.

The FAA will investigate and planned to send inspectors to the scene today, Gregor said.

The pilot told Big Island Fire Department rescue crews he lost power about five minutes into the flight and tried to make it back to the airport but was unable to get back and had to make a "hard landing," according to a statement from the fire department.

There is a steady flow of tour helicopter traffic over the area as pilots follow the Wailuku River to give tourists a view of the waterfalls. Pi'ihonua resident Dudley Nahooikaika said something sounded odd about this particular flight.

"All of a sudden it just faded away, really fast," he said. The tour flights usually fade off into the distance more gradually, he said. Another neighbor reported hearing the helicopter "sputtering," Nahooikaika said.

"They're lucky they crashed into a big grass pad, the thing is so padded," he said.

Neighbors said the area is state land formerly used as pasture for the J7 Ranch and has become overgrown since the ranch shut down about five years ago. The helicopter ended up about a quarter-mile south of a hydroelectric power plant that operates on the upper Wailuku River.

Bob Blair, chief pilot for the tour company, said the helicopter was making a 45-minute tour flight in good weather to the falls and Kilauea volcano. K&S Helicopters, the parent company of Tropical, makes 10 tour flights a day from Hilo, and the pilot was very familiar with the area, Blair said.

"When you make a precautionary landing, that's kind of a rough area up there, and sometimes you're not sure what you're getting into when you set it down because the grass is pretty tall, there's lava rocks, you have no idea," Blair said.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.