Billy Werth loves the thrill of spinning his high-performance biplane upside down and tumbling through the sky, before pulling up a few feet from the ground, to the delight of spectators like those at the air show in Frenchville over the weekend.

But when the engine of his aerobatic plane suddenly quit 4,500 feet over dense woods in Standish on Sunday, it was no thrill.

“A whole slew of swear words were going through my mind,” Werth said. “You get a minute of ‘I can’t believe this is happening,’ a couple seconds of troubleshooting – trying things with the airplane to get it to do something. None of it’s working – you’re going to put the airplane down.”

Headed home from the Acadian Heritage Air Show in northern Maine, cruising toward his refueling stop at Sanford Seacoast Regional Airport, Werth’s engine cut out at 5:30 p.m.

“I was just flying along and the engine just stopped. It acted like it was out of gas, but it wasn’t out of gas,” he said. “I knew I had gas in the airplane. It just wasn’t getting any to the motor.”

Encased in a tiny cockpit packed with gauges and levers, Werth, 44, tried to diagnose and fix the problem, furiously working a manual fuel pump and adjusting the air-fuel mixture while trying to restart the engine. After a few seconds it became clear his efforts weren’t working, and he had no time to puzzle it out or try anything else.

The experimental Christen Eagle is capable of incredible feats in the air – even flying upside down over the runway so low that his brother, speeding along on a motorcycle, can grab the plane’s tail. But without power, the stubby aircraft flies “like a bag of wet hammers,” Werth said.

“If you have an engine problem, you’re not looking over there for a field,” he said. “You’re looking right below you.”

He started to manage his descent.

He saw power lines crossing and oncoming traffic on the road below him. He would have preferred a nice smooth field, and there were a few open patches, but without knowing what the ground was like, he couldn’t risk it. One deep rut or large stone would flip the aircraft.

A few minutes earlier when there was no road close by, he might have ditched the plane, jumping out to land with a parachute.

Instead, he aimed for a stretch of Route 35, with only minimal influence over where and when he would come down.

He had three goals: “I didn’t want to hit anybody on the ground, I don’t want to kill myself, and can I do this without buggering up the aircraft?” he said.

His immediate goal became gliding just far enough to avoid landing in front of four oncoming vehicles.

From his perch aloft, Werth could see three cars and a motorcycle, but they probably weren’t scanning the sky for an airplane that was planning to land. They wouldn’t have time to swerve out of the way once he was in front of them, even though the plane’s 20-foot wingspan would leave room to avoid a collision.

At the last second, he adjusted his flaps to lift the nose up as much as it would go, and the plane clipped a branch arched over the road.

He cleared the final two vehicles – a motorcycle and beige Ford Trailblazer – by a few feet before he finally hit the pavement. He’s not sure whether they swerved to avoid him or not. The plane’s fuselage extends 12 feet forward from the cockpit, so he couldn’t see right in front of him.

Werth, who studied to be a pilot at Indiana State University, prefers to call Sunday’s abrupt arrival a “hard landing” rather than the first crash of a career that includes flying KC-135 aerial refueling aircraft for the Air National Guard, several missions in Iraq and Afghanistan, and as a pilot for a small regional airline in his hometown of Indianapolis. At first contact, the wheels and the struts that support them collapsed, and his momentum slid the airplane into a ditch. The plane tipped up onto its nose, and for a precarious moment, Werth worried it would topple over, slamming upside down onto the thin canopy over the cockpit.

Instead, it flopped back onto its belly.

What the Christen Eagle lacks in gliding ability it makes up for in strength. It needs to withstand the intense forces of aerobatics – the loops and barrel rolls and pulling up sharply from a nose dive. That sturdy construction – along with a restraining harness and helmet – may have saved Werth from more serious injury, he said.

Werth did a quick inventory of his body. He was bleeding and he quickly realized it was a finger on his left hand, which ultimately required two stitches. The rest of him felt – all things considered – OK.

“Even before I got out of the airplane I was wiggling fingers and toes,” he said.

The vehicles he had just missed pulled over. The first person to reach him was a pilot who helped Werth get out of the plane.

“He was surprised I wasn’t buggered up more. I think he expected more body parts,” Werth said.

The second was a nurse who doubted he was as uninjured as he said.

Above them, a fellow pilot flying a similar plane circled helplessly overhead before continuing to Sanford.

Werth agreed to be taken by ambulance to Maine Medical Center and was released later that night.

On Monday, Werth was walking gingerly, dealing with a full-body ache but no serious injuries. A biplane pilot has to pack light, and Werth was still wearing the blue jeans he had on Sunday, a bloodstain showing on the left side.

As he drove to check on his plane, which had been carried by Copp Motors to its facility in Cumberland, he fielded a series of telephone calls from other stunt pilots.

They wanted to know what happened, to make sure he was OK, and to find out if there was anything they should know in case of a similar situation.

“Air show flying is not dangerous,” insisted Werth, who started training to become a stunt pilot in 1991. “Getting to and from the air show is dangerous.” The aerobatic aircraft are not designed for long-distance flights. At the air show, at every stage of every trick, pilots have trained on what to do if their engine cuts out. And invariably there is a huge runway beneath them.

When Werth arrived at his plane, he was surprised at how intact it was, although it will never fly again.

A splintered wooden spar protruded through the fabric on one of the wings like a broken bone poking through flesh. The propellor blades were bent back from the impact of the crash, and the front of the fuselage containing the large engine was partially split from the rear half of the plane.

Werth said he may be able to salvage many useful parts. The plane is insured, and he has no doubt he’ll be flying again, although not in time for next weekend’s show in Rochester, N.Y.

“I’m just happy to be here and happy to talk to all my friends on the phone,” he said. “I never want this to happen, but that’s why we train for it.”