Brake Tests 'Copter Transmissions in Record Time

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Oil Shear Brake Takes Helicopter Transmission Overhaul from Drawing Board to "Mission Accomplished" in Record Time


Professional Aircraft Accessories (PAA), a Greenwich AeroGroup company based in Titusville, Fla., needed a dyno that would allow them to test helicopter transmissions after overhaul, and they needed it fast.  This Federal Aviation Administration (FAA) and European Aviation Part 145 Repair Station specializes in the repair and overhaul of landing gear, accessories, instrumentation, pressurization, radio, radar avionics, and airframe components, offering component capabilities on fixed wing aircraft such as Bombardier, Boeing, Lockheed, Gulfstream and more.  Expanding into the helicopter market was a natural, and a Request for Quotation for overhaul and recertification of LH58 Kiowa helicopter transmissions was a perfect opportunity.  The only caveat was a condensed timeframe.  Thankfully the team at PAA found that oil shear braking technology helped them meet not only the technical requirements of the project but also the fast response needed for initial certification testing.


Cleared for Takes Off


Once the RFQ was approved, PAA had essentially four months to design and build a dynamometer test stand, and overhaul three transmissions to get their project verification audit from the Army.  Jerry Leach, Director of Production Engineering & Planning led a team of people to begin to design the system, and race against the clock.


“We decided to dump power into the system and then load it via braking,” said Leach. 


Power is supplied via a General Electric (GE) electric motor and variable frequency drive (VFD) combination with 700 horsepower and 3,600 rotations per minute. The specification calls for testing at 40-60-80-100-and 112 percent of load for various timeframes.  Load is supplied by a TB 83 oil shear brake from Force Control Industries which can be precisely controlled to meet the various spec points.


At 112 percent of load, Leach cited 8,200-foot-pounds of torque. The test takes about an hour, Leach said, during which there is very little temperature rise. 


The success of this project was important to PAA and Force Control but it is vital to the brave men and women who rely on the Kiowa reconnaissance aircraft day-in and day-out, or, more appropriately, night-in and night-out. Rebuilding the transmissions quickly yet proficiently and getting these armed scout aircraft back into service is a top priority for the Army. Thanks to cooperation between customer and vendor as well as the robust and reliable oil shear braking technology employed in the custom dynamometer test stand at Professional Aircraft Accessories in Titusville, Fla., PAA can tell the Army, “mission accomplished.”   Read the whole story here