Thursday, June 1, 2006
A Hospital For Rotor Blades
Around the world, Composite Technology provides the edge to keep these vital structures cutting through the air.
We hang then, we balance them and we trim them. We inspect them, we tap on them, and we turn them with mighty engines. They hunt, they feather, they lead and they lag. And even though we try our best to protect them, they sometimes get banged up, bent up and shot up. They are rotor blades. But when they are damaged, they don't necessarily have to be taken to the trash dumpster. Once in awhile, they can actually be fixed.
In the middle of an industrial park in Grand Prairie, Texas, sits a rotor blade hospital of sorts. It is Composite Technology, Inc., a newly acquired subsidiary of Sikorsky and one of only a few companies that can repair rotor blades.
While in Dallas for Heli-Expo 2006, I drove 12 mi. west to visit CTI, and to see for myself how something as precisely made as a rotor blade can be fixed.
Upon my arrival, I was introduced to Terry Reininger, the senior director of program development. He would be my tour guide. Tall, trim and sporting a friendly air of confidence, Reininger did not have to tell me that he was a retired military officer. It was written all over him.
The first stop on my tour was the first stop for incoming blades: the loading dock. Reininger explained that the wooden crates all around me contained main- and tail-rotor blades from all over the world, some from original equipment manufacturers and some from consumers.
Once the crates are opened, the blades are removed and placed on a rack for initial appraisal. An inspector will check the tag on the blade to see why it was sent. Some have suffered damage from minor accidents, such as being dropped or bumped into something, while others have delaminated--a condition in which the thin, protective covering begins to separate from the blade. A few incoming blades are brand new, and have been sent by the manufacturer for modification prior to sale. Still others are in for overhaul.
Reininger explained that some inspections include tapping on the blade with a very small hammer to see if it "sings" (that's good) or thuds (that's bad), while other inspections are performed using ultrasound--a process that shoots high-energy sound waves through material, using their echoes to identify damaged areas. X-ray machines are commonly used, too.
A much more low-tech method for finding problems with a rotor is "dipping." Technicians will dip blades into a trough of water. Tiny bubbles streaming from a blade will pinpoint a hole that may need mending. "It's simple, but it works," laughed a technician.
Reininger explained that CTI is the only authorized repair depot for both main and tail rotor blades for the U.S. Army's AH-64 Apache attack helicopter. For about $2,000 per blade, CTI can overhaul a timed-out Apache tail-rotor blade and add another 6,000 hr. of service life to the $15,000 component. "We get a lot of those here," explained Reininger while pointing to a rack of Apache tail rotors. "We save the Army a lot of money overhauling their blades."
CTI is also an authorized blade repair and modification facility for AgustaWestland, Bell, Eurocopter, Kazan, MD Helicopters, Schweizer, and Sikorsky. When I asked why there weren't any blades for the popular Robinson R22 and R44 helicopters, I was told their rotors are relatively inexpensive, and only have a 1,200-hr. life. As a practical matter, it's easier and cheaper to buy new Robinson blades than to fix old ones.
Dozens of employees were buzzing around the shop working on or supporting the work on blades. There are 55 workers in all at this location, which serves as CTI's headquarters. Another 45 workers are scattered among smaller facilities in Brazil, Canada, England and Singapore.
When an internal problem with a blade has been located, a technician will cut the skin away with surgeon-like precision to expose the damaged material inside. Reininger showed me a rotor blade with a 6-in., oval-shaped portion
of its skin removed and its orange honeycomb center exposed. "We'll take blades like that, fix or replace the core material, and re-skin them," said a passing worker. "When we're done, you can't even see where the problem was."
Some blades are actually okay when they arrive, but the OEM has developed an upgrade to their design that CTI is authorized to perform. For one kind of blade, it could mean modifying the leading-edge strip, while others might receive a root alteration.
Once the surgical repairs are done, the blades go to the Heat Survey Room. There, a CTI technician clamps each blade inside of a rubber-like sleeve called a "blanket." The blanket is then heated to precise temperatures to cure the materials and laminates used during the repair. A blade can spend several hours curing at 250F in a blanket made specifically for that model. "We have a blanket for every size main rotor and tail rotor we repair," said Reininger. "We also have a portable machine to send into the field with a technician." There is also a room with small blankets for treating spot repairs.
Once a blade has been repaired and treated by the heat-survey equipment, it's time for a fresh coat of paint. CTI has its own painting area, where masked craftsmen spray fine mists of paint back and forth in rhythmic motion over blades.
Once a coat of paint has been applied, the blade will be taken to another room where it will sit in a 120F heat chamber until the paint has completely dried.
The last stop on the tour was the balance room, where all blades coming out of repair are balanced to the original manufacturer's specifications. Lining the walls were racks of helicopter blades with their roots painted a bright yellow to designate them as control samples. Once CTI has repaired and painted a blade, its weight is adjusted to match that of the control sample.
Before CTI got its highly precision balance equipment, the Army had to take five to six maintenance flights in order to set the proper track and balance on a repaired blade. Now, only one or two flights are usually needed, because CTI's balancing gear is so accurate.
After leaving the shop, I was taken to the administrative section of the building to meet Michael Topa, CTI's president.
When asked why CTI is the choice of so many manufacturers throughout the helicopter industry, Topa, an accountant by training, said, "We work strictly to OEM standards. We take revenue out of the equation when it comes to safety."
Topa attributes the company's success to the people who work there, since a blade can take as many as 140 labor-hours to repair. He said he even eats his brown-bag lunch with various teams on a regular basis to encourage the free exchange of ideas and concerns.
When asked about the recent merger with Sikorsky, Topa said he sees it as an excellent move that will drive CTI's growth. "In the future, you'll see more [CTI locations] on the map," he declared.