Major maintenance on helicopter drivetrain components having specific overhaul times, life-limited parts, and other unique requirements is generally reserved for the maintenance repair overhaul (MRO) organization having dedicated facilities, specialized equipment and tooling, inspection and repair processes, and technicians having specialized skills and training. These facilities will have machining equipment, cleaning and nondestructive testing lines, welding sections, test or flow benches, paint booths, and are more similar to a specialized machine shop than the typical aircraft maintenance facility. Many times these specialized facilities provide MRO services for both civilian and military customers.
I recently had the opportunity to visit such an MRO facility; Timken Aerospace Aftermarket Solutions in Mesa, AZ, where a steady volume of repair and overhaul takes place on Pratt & Whitney Canada PT6A and PT6T TwinPac engines, Honeywell T-53 engines, Bell Helicopter drive train components, and Rolls-Royce 250 component repair. Some of the more complex units repaired and overhauled there are the Bell 212 and 412 transmissions, Bell 412 main rotor heads, and the Honeywell T-53 fuel control units.
More than just bearings
I, like many other people, naturally associate the name Timken with bearings — and rightfully so as it has been manufacturing bearings of all sizes, shapes, and applications for decades. But that’s certainly not all it does. Erik Paulhardt, vice president of Timken’s Aerospace and Defense segment, explains, “The Aerospace and Defense group is an original equipment manufacturer (OEM) for rotorcraft transmission assemblies, and a variety of complex parts for gearbox and engine applications including bearings. We also produce a host of engine, gearbox, and other piece parts, including bearings, under parts manufacturing approval (PMA). The rest of the Bearings and Power Transmissions Group focuses on the manufacture and repair of roller bearings, ball bearings, gear and chain products for use in numerous OEM and aftermarket industrial market segments.”
Larry Shiembob, director of aerospace aftermarket, says, “We really have the helicopter industry covered as a supplier providing new OEM bearings to helicopter manufacturers as well as replacement parts and numerous MRO services. Our MRO services include working on transmissions, gearboxes, main rotor components, gears, housings, certain turbine engines, and of course bearings. These capabilities place us in the unique position of being able to provide MRO for drivetrain components, repair for piece parts and bearings, provide OEM and/or PMA replacement parts, and provide engine overhaul for certain turbine engine models for light to medium size helicopters.” All bearing repair work is accomplished at the Timken facility in Los Alamitos, CA. Shiembob concludes, “We work with the customer to make sure they understand what options are available and to help them determine which option to choose.”
The Mesa facility employs approximately 80 people and about 90 percent of the shop technicians are FAA certificated either with an Airframe and Powerplant or a Repairman certificate. In the shop are experienced A&Ps, new A&Ps, and former military technicians having helicopter maintenance experience. Technicians receive a blend of ongoing training depending on what their role is including factory training, in-house classroom, and on the job training. Staff may be cross-trained as Timken views this as an advantage, making technicians flexible and allowing better support for the customer base.