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There are few people who know more about bad days for flying than Brian De Bruin and his team at GE’s jet engine testing facility in Peebles, Ohio. The team’s job is to make sure that GE engines keep working when they run into bad thunderstorms or a stray seagull. They expose the machines to hail and monsoon rain, hit them with bird carcasses, and even set off small explosions inside to simulate blade failure. “Some of these tests are relatively benign, but others are quite damaging,” De Bruin says. “You’ve got to prove that your engines are good.”
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De Bruin is the site leader at the Peebles Test Operation, located in a bucolic corner of Ohio where GE has been putting engines through their paces for six decades.
When the site opened in 1954, the five technicians who worked there poured concrete for the first test stand and brought their measuring instruments in a moving van. They were led by Leo “Pappy” White, a legendary GE engineer who had been previously firing captured German V-2 rockets at the White Sands Missile Range in New Mexico.
White and his team started testing new jet fuels and engines at Peebles. "Back then, you could stand 100 feet behind the jet engine and have a conversation," remembers Orvile Jones, 93, who took over as manager of the site after White left.
At the time, Peebles was a lonely place. “Besides the five of us, there were five security guards patrolling the property on horses and making sure that people didn’t come near where we running secret operations,” Jones says.
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The secret operations included testing borane jet fuel. “They idea was that the fuel would give us more power, but it produced terrible white smoke instead,” Jones says. “The local fire department thought the place was on fire.”
Business was so slow that Jones decided to buy hundreds of Christmas trees for a penny a piece and plant them on the 5,000-acre property. He planned to sell them to GE employees in Cincinnati and make the company some money. “We wanted to make profit rather than just noise,” he says. “But the idea was a clunker. When management found out, they got mad. They thought we were wasting time and resources.”
After four years at Peebles, Jones moved out to California to work on the first spy satellites, the site was mothballed and the Christmas tree farm has grown into a forest.
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Engines must survive encounters with golf ball-size hail. Top image: Internet sensation Marquese Scott recently danced inside a Peebles test cell. Image credit: GE Aviation
The machine that rescued the Peebles facility from disuse was the U.S. Army’s odd-looking vertical-takeoff aircraft called the XV-5A. The plane used two GE jet engines to fly forward and two large fans embedded in the wings that were driven by the jet exhaust to hover or move vertically.
“It was primarily the experience we had gained with the large fans in the XV-5A…which enabled General Electric to develop an advanced technology engine core culminating in the creation of the first high-bypass turbofan—the engine of today and the near future,” wrote Gerhard Neumann, the late aviation pioneer who ran GE’s jet engine business in the 1960s and 1970s.
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The XV-5B, which followed the XV-5A, in a hover mode. You can see the two large fans on the bottom of the wings. Image credit: NASA Test Pilot Daniel Dugan
Today, pretty much every commercial jet engine is using this high-bypass turbofan design, which combines the thrust of the classic turbojet engine with power produced by a massive fan at the front of the engine – hence the name turbofan. GE developed the first high-bypass turbofan, the TF39 engine for Lockheed’s C-5 transport plane, and tested it at Peebles.
The TF39 begot the commercial high-bypass line of engines: the CF6, which still powers many Boeing 747s, including Air Force One; the GE90, the world’s most powerful jet engine; the GEnx for the Dreamliner; the LEAP; and many other engines.
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Every single design had to prove its mettle at Peebles, which now has 11 test stands and covers an area equal to nine of New York City’s Central Parks.
Plenty of land helps keep GE from being a noisy neighbor, especially when engineers are testing engines at takeoff speeds. Extra space also allows it to stay within environmental regulations, which limit emissions per square acre, since testing gobbles up millions of gallons of jet fuel every year.
There are four indoor test cells and seven outdoor stands sprinkled on hilltops around the property. Seven of the sites are capable of testing engines pumping out 150,000 pounds of thrust. That upper limit hasn’t been necessary yet, since the world’s most powerful jet engine, GE90-115B, is rated at 115,000 pounds.
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Drinking from a fire hose does not seem so hard after watching a water ingestion test. The test test blasts 800 gallons of water per minute inside a GEnx engine running at full thrust. Image credit: GE Aviation
The U.S. Federal Aviation Administration and other regulators require engine makers to run jet engines through dozens of tests before they are certified to fly. One of the most dramatic trials performed at Peebles involves testing for a “blade-out incident,” an event when a fan blade breaks and the fragments get sucked inside the engine. “It’s not pretty, but the engine casing must be strong enough to contain the debris and protect the aircraft,” De Bruin says.
Workers simulate a blade-out by removing material from the fan blade and replacing it with a piece of plastic explosive. “We set it off remotely when the engine is in the right phase, say, operating at fan red-line speed,” De Bruin says, referring to the highest speed the fan can run.
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Perhaps the strangest structures at Peebles are the turbulence control sphere (on the left) and the wind generator (right). The sphere serves as a wind shelter for controlling wind intake during simulations of engine distress. Image credit: GE Aviation
Researchers also use pneumatic air cannons to fire bird carcasses at engines to simulate bird strikes, and shoot hail the size of golf balls into the fans.
Another tribulation called the endurance test exposes engines to the equivalent of years of service in just a few months by letting them run continuously, save for normal servicing. “Nobody says it’s easy, but our engine must meet the highest standard,” De Bruin says.
Up to 10 “development” engines are built for each new engine design, De Bruin says. Technicians test them, open them up for inspection, rebuild them and test them again.
The team at Peebles is currently testing the LEAP jet engine developed by CFM International, a joint venture between GE Aviation and Snecma (Safran). It is the first jet engine with 3D-printed fuel nozzles and ultra-light parts made from heat-resistant ceramic matrix composites (CMCs). CFM has received more than $100 billion (U.S. list price) in orders and commitments for over 7,700 LEAPs. The engine will enter service in 2016.
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The LEAP recently took its maiden flight on GE’s Boeing 747 test jet over the Mojave Desert. Image credit: GE Aviation
The demand for GE’s new aircraft engines is making Peebles grow. GE has hired more than 100 people at the site over the last three years. The company has also invested $70 million in technology upgrades, like a new indoor testing unit that is big enough to accommodate the GE9X, the largest jet engine ever built with an 11-foot-diameter fan. (The engine is still in development.)
But technicians at Peebles are not only developing jet engines, they also making them. De Bruin and his team take every single one for a spin before it leaves the gate. “It’s us whom the engines now put through an endurance test,” he says. “But it’s a good thing.”