Scale-tipping 44,000 hp motor returns to AEDC

  • Published
  • By Philip Lorenz III and Shawn Jacobs
  • AEDC/PA
Arnold Air Force Base, Tenn. --  Crane operators and riggers recently offloaded a 44,000 horsepower, 80-ton exhaust plant drive motor at AEDC's C-Plant exhauster.

C-Plant consists of an airside and an exhaust side complex. Collectively, the plant is a pressure, temperature and humidity conditioning facility that supplies air to turbine engines and replicates the conditions they experience in flight at desired Mach numbers and altitudes in all the jet engine test cells at AEDC.

Located at the Aeropropulsion Systems Test Facility (ASTF), the air supply compressors can provide up to 1,500 pounds of air per second into the test cell to simulate airspeeds up to 1,800 miles per hour. ASTF provides the United States with the unique test capability of simulating flight conditions at altitudes up to 75,000 feet, at speeds up to Mach 2.3 for engines rated up to 100,000 pounds of thrust, according to Tim Layton, ATA's Aeropropulsion Plant Operations branch manager.

The E311 exhaust compressor system is the third stage of the ATSF exhaust plant. It can be operated to support single, two or three stage operations of the exhaust plant.

The E311 drive motor was damaged in an electrical overload event that occurred in September 2008. A contract to repair the motor was awarded to the original motor manufacturer, Electric Machinery Company, in early fiscal year 2009. The motor was removed and shipped to EM in February 2009. EM completely rebuilt the motor to comply with current motor standards and performed various inspections and tests to validate the motor's repair. The motor was returned to AEDC June 25. It is currently being reconnected and is tentatively scheduled to be returned to service next month, Layton said.

Even though the motor/compressor unit has been out of service for almost two years, ASTF has been able to support all required testing.

"We have a test scheduled to begin in December that will require this unit to be in service, so it is good to see it back in time to get the drive back in operation," Layton said. "With this drive back in service, it will give us more flexibility in supporting all C-1 and C-2 testing. We are restoring full exhaust plant capability."

ATA had to overcome a number of challenges to offload the motor before installing it and completing the repair.

The building's floor would not support the motor weight using conventional means of a tractor trailer. Initially, an attempt was made to find outside vendors who could complete this requirement.

"None of the machinery movers contacted outside of AEDC had a system that would transport the motor inside the building and meet the floor-loading criteria," explained Dave Simmons, ATA's manager of the Model Shop. "That's where that AEDC ingenuity kicked in. Lester Cunningham, ATA's crane and rigging supervisor, met with Brian Monroe, ATA design engineer, on the design of a custom-built transport cart, to be fabricated in-house to roll the motor inside the building. The rigging crew used AEDC'S 140-ton mobile Manitowoc crane to offload the motor from the13-axle outside hauler and transport it to the cart."

Dan Warren, ATA mechanical systems engineer, said there was an additional hurdle to overcome even before the motor could be moved into the building.

"A gravel pad had to be constructed in advance of the motor's arrival," he said. "The gravel pad was topped with two parallel rows of steel plates that were used to interface with a custom cart and distribute the motor weight and to smooth the motor's transition from the parking lot, past the threshold and into the building.

"Once the motor was secured to the cart, a tug motor was rigged to the cart that pulled the motor through the building entrance," he continued. "After being moved into the building, the motor was rigged to the building's 100-ton overhead bridge crane and then lifted and carried across the building where it was set on the easternmost pedestal where it was removed from in February 2009."