New Engine-Testing Facility Enhances Safety, Functionality and Efficiency at Michigan Airport

A new $7 million ground run-up enclosure is boosting safety and operating efficiency at Oscoda-Wurtsmith Airport (OSC), a general aviation airport in northeastern Michigan, along the Lake Huron shoreline.

The roughly five-story structure was completed in February 2024 by Kalitta Air LLC, the airport’s largest tenant and employer. The ground run-up enclosure (GRE) provides the cargo carrier with a safe place to test jet engines running at full bore without endangering personnel and smaller aircraft that might accidentally come too close to a powerful blast of engine exhaust.

“You don’t want to be behind a 747 at full run-up power,” says Airport Manager Jack Brown. “It would blow you into the next county.”

Kalitta currently owns two dozen 747s and five 777s, and is awaiting delivery of six more 777s. OSC is home to its biggest maintenance, repair and overhaul station, which services about 150 aircraft a year. Workers there perform three to five ground run-ups per week, each lasting anywhere from 15 minutes to two hours.

Previously, technicians ran engine tests on various ramps at the 2,300-acre airport. But that negatively affected traffic at the one-runway facility because smaller general aviation airplanes had to use the main taxiway to get from their hangars to the main runway.

“It required a lot of coordination with Kalitta,” Brown recalls. “We’d also have to notify general aviation pilots using UNICOM.”

As the cargo airline expanded its operations with new hangars and other infrastructure, less ramp space was available for engine testing, and need for a new location became more and more acute.

“As we grew, we ran out of safe, FOD (foreign object debris)-free spots to run the engine tests,” explains Steve Vette, Kalitta’s line maintenance manager at OSC. “I had seen these GREs at other airports, so we started inquiring about them around 2020.”

Blast Deflectors Inc. was hired to design the structure. B&B General Contracting Inc. performed the concrete work and Spence Brothers Construction built the facility, starting in summer 2023.

Thrust Tamer

Testing large jet engines in well-trafficked areas can be risky business. A GE90 turbofan jet engine, for instance, can generate up to 115,000 pounds of thrust.

In fact, a 2007 episode of the television show Mythbusters showed a Boeing 747 jet engine blowing over a taxi, a school bus and a small airplane.

Staff members at OSC have witnessed such power firsthand. “One time, an engine blew a loose, roughly 50- by 100-foot section of asphalt right out of one of our ramps,” Brown says. “We found chunks of it 800 to 1,000 feet away.”

Matt Anzai, sales manager at Blast Deflectors Inc., explains that GREs offer a safer alternative. Airplanes back into the U-shaped structure so exhaust from their engines is directed at the curved rear wall, which essentially renders potentially dangerous engine thrust less hazardous by deflecting it skyward, explains Anzai. 

Some GREs are acoustically treated to absorb and reduce noise as well, but that wasn’t the case at OSC because it’s in a rural area with no nearby residences.

Aerodynamic Design

The design of a GRE begins with an analysis of prevailing wind speeds and direction, which helps determine an optimal location. At OSC, that turned out to be on the east side of the airfield, facing west.

The height and size of a GRE are guided by the size of aircraft that will use it, and whether or not noise attenuation is required. The structure at OSC occupies about two acres of land (leased to Kalitta by the airport) and measures 268 feet wide at the front, 198 feet wide at the back and 315 feet deep.

Because technicians need optimum testing conditions, GREs are designed to facilitate the movement of smooth, turbulence-free air into the engines.

“Jet engines ingest a lot of air, and tests don’t go well with tailwinds,” Anzai comments.

The likelihood of a crosswind spoiling test conditions is minimized with strategically located vents on the two sidewalls. The vents create a headwind inside the structure, no matter which way the wind is blowing outside. Naturally, the number of vents needed varies from airfield to airfield. “It’s a function of aerodynamic needs,” Anzai says.

Kalitta’s structure at OSC has more than 200 sidewall vents, and one large vent on the rear wall. The tops of the walls are rounded to further reduce turbulence.

“With just three walls, it doesn’t look very complex,” Vette says. “But there’s way more to the facility than meets the eye. It’s much more than just three walls.”

No matter how well designed a GRE is, there still are times when it can’t be used because of wind conditions. Vette estimates that Kalitta’s structure at OSC is usable about 85% of the time. This provides much more availability than before, when technicians could only run tests when there was a headwind coming from the right direction.

In total, Blast Deflectors Inc. has designed 21 GREs for North American airports and 60 worldwide.

Built to Last

The structure at OSC is made primarily of roughly 471,600 pounds of corrosion-resistant galvanized steel. The 16-inch-thick concrete pad it stands on required approximately 4,000 cubic yards of concrete—enough to fill about 400 cement trucks.

“It’s designed to withstand bearing one of our aircraft fully fueled and loaded, which weighs nearly a million pounds,” Vette reports.

Both he and Brown are pleased with how the GRE has affected safety and functionality at the airport.

“It’s been really nice,” Vette says. “Our guys are happy that they can run engines at high power without worrying about air traffic. They don’t have to talk to other aircraft that are coming in or worry about missing a call from a pilot.” (There’s no air traffic control tower at OSC.)

“The facility also brings down the noise level because the exhaust deflects straight up instead of horizontally,” he adds. “But in the end, it’s all about safety—safety for aircraft, safety for personnel and safety for anyone at the airport.”

Brown says that if Kalitta allows other carriers to test engines at OSC, the airport could increase landing fees and collect other revenue. But that’s a minor consideration compared to the increased safety aspects, he emphasizes.

“The GRE has made our airport safer for everybody,” Brown says. “Big aircraft and little aircraft aren’t a very good mix, but we all have to get along here because there’s one runway. And this facility helps everyone get along great.

“This really has taken our airport to a different level in terms of safety. It’s a feather in our cap.”

To see the ground run-up enclosure at Oscoda-Wurtsmith Airport in action, visit youtube.com/watch?v=lwM7naZec3Y.