For more than two years, NASA engineers have battled aggravating glitches with fuel sensors on America's space shuttles. The launches continued, but the unpredictable readings were troubling.

The last straw came last month, when two launch dates for shuttle Atlantis were scrubbed because of faulty gauge readings. Frustrated, managers with the space agency decided to put the shuttle program on hold. Find the bug, they said, and fix it.

Call the guys in Coraopolis.

CM Technologies is a small company that produces equipment used to monitor and diagnose problems in electrical circuits. Housed in the old post office on Fourth Avenue in Coraopolis, it employs 16 workers whose expertise is trusted by the U.S. Navy, aircraft manufacturers and the nuclear power industry, as well as the National Aeronautics and Space Administration.

"In the broad sense, we are specialists in wire and cable system aging and maintenance," said Sheldon Lefkowitz, 56, commercial director for CM Technologies. "We have representatives around the globe, but this is really the working office."

Mr. Lefkowitz, who earned his master's degree in mechanical engineering from MIT, started the company in the early 1980s with Greg Allan, 45, who earned his master's in electrical engineering from Georgia Tech. The business began in Coraopolis because the two men were in Pennsylvania studying what had triggered the near-disaster at the Three Mile Island nuclear plant in 1979.

"The technology came out of the forensics associated with looking at instrumentation inside the reactor where nobody could access it," Mr. Lefkowitz said.

Mr. Lefkowitz describes his company's work like this: Let's say you have a light that doesn't work. Your first instinct is to change the bulb. But sometimes the problem isn't the bulb -- it's in the wiring.

CM Technologies has developed devices that send pulses along the wires and use sonar-like readings to detect where the fault is.

The big break for CM Technologies came in July 1996, when the company was brought in to investigate TWA Flight 800, a Paris-bound flight that exploded in midair shortly after taking off from New York, killing all 230 people aboard. The explosion was traced to a short circuit in electrical wiring in the fuel tank.

"It brought national attention to the issue of aging wiring systems in older aircraft," Mr. Lefkowitz said.

And it caught the attention of NASA, which was doing its best to keep an aging fleet of shuttles flying into space.

Shuttle Atlantis -- commanded by Stephen N. Frick, a 1982 graduate of Richland High, now Pine-Richland High -- was scheduled for a December launch and a 13-day mission to the International Space Station. But because of faulty fuel sensor readings, everything ground to a halt.

Shaun Green, NASA's assistant chief engineer for shuttles, is the "traffic cop," overseeing and coordinating the various engineering teams that work on the space vehicles at Kennedy Space Center in Florida. He was the one who called CM Technologies for help.

"We've been working with them for 10 years," said Mr. Green, who has worked with the space agency for more than 22 years. "We've used them more for trouble-shooting and double-checking our data.

"Unfortunately, at [Kennedy Space Center], we don't do this every day. It's more sporadic, so our expertise is limited. Greg [Allan] is the expert who goes out in the field and does this kind of work. We do it, but we only do it two or three times a year, versus Greg who will do it several hundred [times].

"We're probably pretty good at it. But this time, we wanted to be sure. We were going to get the best data we could on this test. This was a once-in-a-lifetime test for us."

Like a TV repairman of days gone by, Mr. Allan flew to Florida in mid-December, armed with one of his company's TDRs -- Time Domain Reflectometers -- and helped NASA engineers pinpoint the bad connector, which was then removed and sent to Marshall Space Flight Center in Huntsville, Ala., for reconstruction.

The hand-held TDR was the perfect tool, Mr. Green said, "because when we go into the [shuttle], you're already in confined spaces to begin with. With this, we go in, get data and do analysis after the fact, without running hundreds of feet of cable."

NASA is so enamored with CM Technologies' TDR, that it has one up on the space station.

The results of the testing on Atlantis, Mr. Green said, put NASA on an optimistic path toward a Feb. 7 launch.

Reaching outside the NASA circle of experts isn't unusual. In fact, only about 10 percent of the workers at Kennedy Space Center are employed by NASA. The rest are subcontractors or vendors, working under the supervision of NASA managers.

"NASA itself doesn't have a lot of expertise in the day-to-day operations because we're overseeing everything," Mr. Green said.

But that percentage is shifting. NASA's involvement in the field has been increasing since the Columbia disaster in 2003, Mr. Green said.

"We still have a lot of subcontractors," he said. "We still oversee, but we manage more of what we're doing. Now, we're leading the effort a lot more than we used to."

Still, he said, small companies such as CM Technologies will likely be part of the space program through the 2010 retirement of the shuttles and the dawn of the next generation of space vehicles.

"[CM Technologies] has been a great company for support and meeting the goals of NASA," Mr. Green said. "Smaller businesses seem to be more willing to tailor products to meet our needs. Bigger companies don't quite need NASA. They say, 'Hey, take it or leave it.'"

Mr. Lefkowitz said CM Technologies is used to being called when there is a problem, but he'd like to see companies bring them in more often for "predictive maintenance" on wiring.

"We've been working with these folks for years and solving problems for them," he said. "They love to call us in at the last minute. We've made the pitch; we say to them, 'You know, we need to be involved in your program on the front end of it, to avoid these kinds of emergencies.'

"And more often than not, you get, 'Well, we don't have a problem yet. We'll call you when we have a problem.' It's kind of like driving around without a spare tire."