BANGOR – Sgt. Terry Varney sat on top of a Black Hawk helicopter Thursday inside a hangar at Bangor International Airport, straddling one of the aircraft’s rotor blades while he checked its brakes.

Not too long ago, Varney and his fellow Maine Army National Guard soldiers would have removed the expansive blades just to fit the helicopter inside.

Now there’s plenty of room.

The hangar is part of a $20 million renovation project at the Army Guard’s Aviation Support Facility on Maine Avenue. The 112th Medical Company (Air Ambulance) is in the final stages of moving into the 60,000-square-foot facility this week.

“There’s a lot of parts and ancillary items that come with these aircraft, and we just didn’t have a place to put them,” Col. Dave Smith said Thursday during a tour of the facility.

About a third of the bright, modern facility was renovated, and the remaining 40,000 square feet is new space.

A grand opening ceremony is planned for next month.

The first phase of the federally funded project, completed in 2004, included construction of six heated bays and four storage bays for maintenance on the helicopters. Work is now wrapping up on 27,000 square feet of adjoining office space.

The facility was designed and constructed under the U.S. Army’s strict environmental codes, which mandated segregating debris and using energy-efficient technology.

Natural light filtered into much of the building, which smelled of paint and fiberglass as soldiers and workers in hard hats maneuvered around ladders and debris in the hallways.

A second-floor classroom space can accommodate 150 people, compared to 35 before, and down the hall are exam rooms for the 112th’s flight surgeons, who now work on the Bangor Community College campus across the street.

The construction project is the first major update the Bangor facility has seen since the 1970s. Crews paved over 21 acres of old tarmac and rebuilt 22 landing pads that originally were designed for the outdated Huey helicopters, project manager Patrick Keating of Pizzagalli Construction Co. in South Portland said Thursday.

Besides the Black Hawks, the facility also houses three OH-58 JetRangers, used for drug detection operations, and a C-12 airplane that transports passengers all over the country.

The aircraft enter the bays through massive, 20-foot-high canvas doors that replaced old barn-style sliding doors, and in one hangar, only the steel beams and two brick walls are left from the original structure.

“This was a ratty old mess,” Keating said, standing on a platform overlooking the hangar.

Before the renovation, soldiers had to clean snow and ice from helicopters left outside during the winter, Smith said. Pictures taken during the Ice Storm of 1998 showed icicles hanging off the helicopters, the rotors weighed down like frozen tree branches. The damage totaled $100,000, Smith said.

Now that the aircraft can be housed inside, soldiers don’t have to clean off snow and warm them up prior to flight, Smith said.

The 112th specializes in medical evacuations, but must be ready at a moment’s notice to respond to frequent search-and-rescue operations by local law enforcement. During hunting season, the unit is called out every couple of weeks, Smith said.

One helicopter fully outfitted with medical equipment and a defibrillator already is ready to fly, and five others are equipped with litters and hoists for rescue operations, he said.