Helicopter Hangar Nears Completion

On a 12-acre site at the Silverbell Army Heliport in Marana, Ariz., Sundt Construction of Phoenix is more than 80-percent finished with building an 84,000-square-foot helicopter hangar for the Western Army National Guard Aviation Training Site (WAATS). Based at this heliport is the 1st/285th Apache

Sundt began work on the $14.6-million project in September 2003. It includes 40,000 square feet of hangar, 28,000 square feet of maintenance shops and 16,000 square feet of administrative space. The project also includes a simulator building, drainage channels, a parking lot, and helicopter wash racks.

The project is divided into sectors, and all have a slab-on-grade concrete floor. Each sector's floor, however, has a different thickness, reinforcement and strength characteristics, based on its function.

Sector 1 is primarily a health/fitness area. The majority of Sector 1 has a 4-inch-thick concrete floor reinforced with No. 4 rebar set at 12 inches on center. A small portion of the sector, however, is reinforced with No. 4 rebar set at 18-inch centers. All the concrete floors have a compressive strength of 3,000 psi, except for the hangar floor, which has a 5,000-psi compressive strength.

Sector 2 is approximately 66-percent hangar space and 34-percent administrative. The hangar floor is 7 inches thick and reinforced with No. 5 rebar on 12-inch centers. Sector 3 is a maintenance and office area with a 4-inch concrete floor reinforced with No. 4 rebar on 18-inch centers. Sector 4 is all hangar space with a 7-inch floor reinforced with No. 5 rebar on 18-inch centers. The hangar floor will also have an epoxy coating to increase chemical resistance. Sector 5 is all maintenance space with a combination of 4-inch-thick and 6-inch-thick floors, both reinforced with No. 4 rebar on 18-inch centers. Finally, Sector 6 is all hangar space with a 7-inch-thick floor reinforced with No. 5 rebar on 18-inch centers.

The hangar contains eight 60-foot-by-90-foot bays for the support and maintenance of eight Apache and Black Hawk attack helicopters. The eight hangar doors each measure 60 feet wide and about 30 feet high, allowing the helicopters to enter the bays without lowering or removing exterior parts or equipment.

The hangar is equipped with two five-ton bridge cranes, each spanning half the hangar, or four bays. The maintenance shops are outfitted with two 2.5-ton monorails. Workmen will use the bridge cranes and monorails to move heavy items such as helicopter engines.

There is one utility pedestal for every bay in the hangar. Each pedestal has 400-Hz electric power, compress air and 28-volt DC power. The hangar is equipped with a converter to change normal 60-Hz power to the 400-Hz power that is used by many aircraft components.

The maintenance shops include rotor and propeller, airframe and structural welding, paint, avionics, pneumatics, hydraulics, electrical, engine inspection, battery room, non-destructive inspection, armament subsystems, component cleaning, night vision devices, special tools, repair parts, arms vault, and combustible storage.

Included in the administrative space are offices, aviation life support equipment, conference rooms, fitness room, locker rooms, and break areas.

The building is constructed of standard 8-inch-by-16-inch concrete block walls. A combination of split face and smooth block is used, creating a pattern. Load-bearing walls contain rebar similar to that used in the concrete floors, and they are filled with grout. R-11 insulation batt is employed on the inside of all exterior walls to minimize heat loss in winter and cooling losses in summer. All the building's structural steel is grounded via a copper cable encircling the entire building. A standing seam metal roof covers the structure.

A 2-inch-wide expansion joint in the middle of the building allows it to expand and contract in the east-west direction. The expansion joint runs through the walls, floor and roof of sectors 3 and 4.

The heating, ventilating and air conditioning system is a variable air volume type that uses high temperature hot water and chilled water. The office and maintenance spaces are conditioned through this system, but the hangar areas are cooled using evaporative coolers and heated using a radiant heat system.

The office and maintenance areas have a traditional wet pipe sprinkler system, while the hangar has a foam fire suppression system.

WAATS is the premier site for attack and aero-scout helicopter training for the Army National Guard. This site serves both active duty and National Guard aviators with simulation support, using the AH-1 Flight Weapons Simulator and the AH-64 Combat Mission Simulator.

Helicopter emergency procedures training is conducted at the nearby Picacho Stage field, which has a control tower, crash fire rescue and four emergency procedure training lanes. Picacho Stage field can bivouac an entire Apache battalion.

Weather and flying conditions in southern Arizona facilitate training 360 days per year. The sparsely populated low level and tactical training area encompasses 3,600 square miles, two-thirds of which has been approved for tactical landing zones.

Aerial gunnery training is conducted on the Barry M. Goldwater Gunnery Range and its 2.5-million-acre joint use ranges. Staging from Gila Bend Auxiliary Field, the armed helicopters proceed to East Tac Target Range to practice their gunnery mission.

The new hangar facility is scheduled for completion by the end of September.