Aerometals has received PMA approval for spiral bevel gears for the main rotor transmission of the MD500. According to the company, the approval marks the first time the FAA has granted manufacturing approval for transmission gears to a company that is not the OEM. The testing required a test stand using a 500-hp electric motor instead of a gas turbine. The MD transmission is rated for 425 hp for up to five minutes, but Aerometals ran the gears for eight hours at 467 hp to satisfy FAA testing requirements.
The FAA has adopted a new Airworthiness Directive for the Pratt & Whitney Canada PT6A-15AG, -27, -28, -34, -34AG, -34B and -36 turboprop engines. It requires the removal of certain affected PMA replacement Timken Alcor Aerospace Technologies first-stage reduction sun gears and/or the interacting planetary gear sets from the propeller reduction gearbox assembly.