Aerometals announced that the company has received PMA approval for spiral bevel gears for the main rotor transmission of the MD500 helicopter. This is the first time the FAA has granted manufacturing approval to a company for transmission gears who is not the OEM.
“Receiving the PMA approval is a great achievement for our engineering team at Aerometals, we’ve been working on this project for some years,” said Aerometals President Rex Kamphefner. “No one except an OEM has ever received FAA manufacturing approval for main rotor gears before. Our customers know and trust our products and they expect both engineering improvements and reasonable pricing.”
In order to perform testing to meet the stringent requirements of FAA FAR part 27, Aerometals designed and built a test stand using a 500hp electric motor instead of a gas turbine. The MR transmission is rated for 425hp for up to 5 minutes, but Aerometals ran their PMA gears for 8 hours at 467hp to satisfy FAA testing requirements. As part of their testing, Aerometals’ gears were also mixed and matched with OEM gears, and performed flawlessly. The PMA gears also incorporate new technology to impart a mirror finish to the gear teeth. “These gears will actually allow the transmission oil to run a few degrees cooler because of reduced tooth friction,” said Kamphefner.
“We did not want to simply meet the minimum requirements. We set out to incorporate improvements to the product based on 30 years of service history,” he added.