When Telford Allen II founded an aircraft charter company in Waterville more than 20 years ago, he started with four employees, two planes and one modest plan: Develop the charter business, sell and maintain a few planes and become the airport’s fixed-base operator.

The Greenville man, who earned his private pilot’s license before graduating from high school, couldn’t have known what the small business would become.

Today, The Telford Group is a $50 million company boasting 125 employees in Maine, a booming parts sales business and millions of dollars in government contracts. It’s a long way from the two-plane, two-pilot operation of 1982 – the company is even building a blimp airship that requires no pilot at all.

“It’s amazing,” Allen said Wednesday. “Some of it’s been luck, some of it’s been real hard work.”

Now mostly retired from the business, the 60-year-old Allen has turned over operations to his two sons and former Bangor International Airport director Bob Ziegelaar. Telford Allen III serves as chairman, Travis Allen as vice president of operations, and Ziegelaar as president.

The men oversee a company, now based in Bangor, much different from that of its founder’s. The once bread-and-butter charter operation has been stripped away, the air cargo division sold off, and locations added in Alabama, Texas and Maryland. Parts sales and government contracts now make up the bulk of the company’s business, followed by aircraft repair, leasing and sales.

On a recent tour of one of Telford’s two facilities at Bangor International Airport, Ziegelaar walked among rows of 30-foot-high shelves of boxed parts, explaining the success of the parts sales operation that increasingly makes up Telford’s business.

“With parts going all over the world, it doesn’t really matter where you are,” he said, a plastic-wrapped propeller hanging on a nearby beam.

The company has personnel stationed on several continents and ships parts, from engines to cockpit radios to toilet seats, all over the world. Numbering in the thousands, the parts are all inventoried in a computer program that can locate the components down to the row and shelf, Ziegelaar said.

Technology similarly is being used at Telford’s location in Limestone at the former Loring Air Force Base. The company is working with a San Diego-based research and engineering firm, SAIC, on a government contract to construct a 92-foot-long unmanned blimp, a project that began roughly two years ago that so far has totaled more than $4 million, Ziegelaar said.

The airship essentially can be flown using a laptop computer, either remotely or through preprogrammed coordinates, he said. SAIC takes care of the electronics and piloting work, while Telford’s focus is on engineering, Ziegelaar said.

“Our task is to make it flyable,” he said.

The blimp is outfitted with surveillance equipment. Its uses are varied, from patrolling borders to searching for lost people in the Maine woods to counting wildlife, Ziegelaar said.

“It can operate day and night,” he said.

Telford plans to make the airship, the first of its kind for the company, operational by the end of the year, then perfect the model and move on to a larger blimp, he said.

“We would like to develop Loring further,” Ziegelaar said. “Testing and development seems like a logical arena.”

Government contracts now represent nearly half of Telford’s business, and also include maintenance and support for turbine-powered aircraft and border patrol aircraft in the Southwest, he said.

Back in Bangor, maintenance work keeps Telford’s Odlin Road location humming with the clanking sounds of repair work. On a recent tour of the facility, which Telford leases from the city, mechanics crawled in and out of a 35-seat, DeHavilland Dash-8 regional turbine airplane, checking components and making repairs.

Aircraft arrive at Telford from all over the world for regular maintenance, and are dismantled from ceiling to floor and reassembled within about a month’s time, Ziegelaar said. For every day they’re not flying, the planes are losing money for their owners, he said.

“The whole airplane gets torn apart,” Ziegelaar said. “It’s an incredibly intense project.”

With the maintenance business brisk, Telford has hired approximately 20 mechanics in the last six months, and the company expects to hire 20 more to meet demand, Ziegelaar said.

Just this month the company has become involved with regional jets, a newer generation of regional aircraft now being seen in Bangor that are faster, bigger and quieter, he said.

Adapting to such changing markets has been a key ingredient to the company’s success, the senior Telford Allen said, reflecting on the progress of the business over the decades.

Looking back, Allen and his wife still shake their heads at the how the business has evolved from a small charter plane operation to a multimillion-dollar company now venturing into unmanned airship technology, he said. The work has been challenging and consuming at times, and has prompted Allen to cut back his involvement in the company as the years pass, he said.

“I do what I’m told,” he joked. “It’s like owning a mom and pop store. You’re at it seven days a week, 24 hours a day.”

Despite his declining involvement, Allen, who still flies about every other day, is confident that the company will continue to search out new aviation products and services to adapt to the industry’s changing needs, he said.

“We’re always out there looking for new things,” Allen said. “We work hard at keeping pace with the changes in the state of Maine.”