• Comanche is first U.S. helicopter to use split torque gearbox
• Prototype was designed before the new indexing theory was available
• Measurments made on the prototype gearbox showed the four load paths were not sharing the load properly
• Prototype gears were loaded beyond acceptable limits because of the unequal load sharing

• NASA and Army researchers developed a new theory and software to explain and solve the load sharing problem
• Sikorsky, NASA, Army researchers together used the new theory and software to invent a design solution
• After redesign, loads of all power paths are within design limits

• Load sharing problem solved quickly & cost effectively by NASA/Army software
• Time consuming, costly trial-and-error approach avoided
• Patent # 5,813,292, (co-inventors Army Research and Sikorsky)

Point of Contact: Tim Krantz  (216) 433-3580,  Timothy.L.Krantz_AT_nasa.gov
NASA Glenn Research Center / Army Research Lab Vehicle Technology Center
Structures and Acoustics Division / Mechanical Components Branch