Loss of lubrication to the main gearbox (MGB) has been responsible for several crashes, ditchings and precautionary landings in large transport category helicopters in recent years. These accidents set off broad debate as to exactly what is required of main gearboxes under Part 29 certification of the U.S.
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.
Pascal Chrétien, the designer and pilot of an electric rotorcraft that flew in 2011, is forming a company that aims to offer hybrid power for aircraft, notably helicopters. The patented technology is called Tetraero, and according to its promoters its main benefit would be in safety.
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.
Bell 206B JetRanger, Cleveland, Ohio, June 25, 2005–A failure of the main drive shaft for undetermined reasons, the NTSB concluded, caused the total loss of engine power in the Bell 206B JetRanger. A factor in the accident was the pilot’s improper flare.