By Gary Rice
NADEP NEWS Editor

Unlike the O’Reilley Factor, the NADEP Cherry Point whirl tower is anything but a no-spin zone.

The whirl tower, in Building 1793, spins a variety of rotor blades on a regular basis in support of the depot’s helicopter maintenance programs. But its 30-year-old motor was having a hard time keeping up with the workload. That’s when the engineers of Plant Engineering’s Industrial Production Support Department stepped in.

“When the depot took over the H-53 program, we needed a more powerful motor to spin those bigger blades,” Bill Webster, Electronics Engineer, said. “The old motor could do the job for very limited lengths of time, but it lacked the required horsepower, and there was always the danger of overload. It was just a question of how long the motor would last. That was the genesis of our motor replacement project.”

“We didn’t want to wait for it to fail with catastrophic results,” Mechanical Engineer Danny Fincher said. “So we determined what new motor would be the best value for the depot and wrote up the requirements and specifications. Now, with the increase in horsepower, they don’t have to limit the spin time for H-53 blades anymore and can run them all day long if necessary.”

“This was a project that spanned several years,” Industrial Engineer and Project Manager Sheila Cuthbertson said. “We spent many long hours in planning, and many people at the depot were involved.”

“We were fortunate to have so many skilled depot artisans and maintenance personnel available to assist us with the installation process,” Fincher added. “If we needed something manufactured, removed, adjusted, or reassembled, we’d call the machinists and maintenance people over. They would have the project back on track quickly.”

Built by Teco-Westinghouse, the new motor took about seven weeks to install and came on line on Feb. 19. It is 12 feet in diameter at the mounting feet, 12 feet tall, and weighs about 77,000 pounds. It was built in the same dimensions as the old motor so that it would fit in place.

Rotor blades have to perform identically so they can be replaced one at a time on any helicopter. As they get old, their flexibility and static balance may change. In the whirl tower, two production blades are run in conjunction with a master blade and are adjusted using trim tabs or weights to exactly match the master blade.

“With the new motor, the depot can now test and adjust any rotor blade in the Department of Defense inventory,” Fincher said.

The new motor will benefit the depot in a number of other ways as well. It will save money as it is more energy efficient and requires less maintenance. And since it does not use lubrication oil, it will also have less impact on the environment.

“In the year 2000, the depot ran 528 blades,” Cuthbertson said, “and that number has since increased. If that old motor had failed, NADEP would have lost a significant amount of work. As it was, our biggest challenge was to minimize the effect on production by minimizing the whirl tower’s down time. Lots of issues and problems cropped up; but we told the production people the project would take no more than 53 days, and we were determined to bring the tower back on line within that timeframe.”

“Little things kept going awry after we set the new motor in place,” Webster agreed, “but with the war in Afghanistan going on, we knew we didn’t have the luxury of taking our time getting it installed. The Rotor Blade Shop had to get its blades done and get back on a regular schedule.”

“Fortunately, everything went very smoothly,” Cuthbertson said. “Everyone stayed right on top of things, and we finished the project ahead of schedule. That was a satisfying result for all of us.”

Photo Caption: With the new motor in place behind him, Test Cell Operator Joseph Sparrow stands next to the old motor at the NADEP Cherry Point whirl tower. (Gary Rice)