Ampaire has reached agreement with the FAA on the type certification basis for its AMP-570 powertrain, the first for a hybrid-electric propulsion system.
Stage 4 final agreement on the G-1 issue paper, the regulatory framework for certification, paves the way for Ampaire to finalize the G-2 means of compliance, which includes the testing required for certification.
“These are milestones that hopefully not only move companies forward, but help move the industry forward,” says Kevin Noertker, cofounder and CEO of Long Beach, California-based Ampaire. The startup is aiming for type certification of the AMP-570 under FAA Part 33 rules for engines and supplemental type certification of its first application, a Cessna Caravan retrofit, by the end of 2026.
Once Ampaire completes a fundraising round underway, “We have about 18 months’ work to get through,” Noertker says.
The H570 is a 500-kW-class integrated parallel-hybrid powertrain, with both the combustion engine and electric motor driving the propeller.
“The foundational safety of the system is a direct drive from the combustion engine to the propeller plus the mechanical output of additional power from the electric half of the system,” Noertker says. “That means there is additional fault tolerance, but there is also a safety case for the aircraft that’s almost completely agnostic to the health of the electric system.”
“From a Part 33 standpoint, when you’re talking about failure modes and effects, if the electric system shuts off and you’re able to fall back on a fully functional and FAA-approved combustion portion, that’s pretty resilient,” he adds.
The H570 is based on a RED Aircraft A03 compression-ignition piston engine, which runs on jet fuel. The A03 is already certified by the FAA. “The beauty of the strategy we’re taking to open up this market is we are able to leverage the existing data, trust and certification for the combustion engines we’re using for a family of hybrid propulsion system,” Noertker says.
Ampaire flew the first-generation H570 in a modified Caravan in November 2022. The company is now integrating the certification-intent powertrain into the Caravan, with flight testing planned to begin this summer.
The electric motor is coaxial with the combustion engine in the Gen 2 system, resulting in a slimmer nose profile. The startup is developing the battery pack for the Caravan using modules provided by Electric Power Systems.
The battery system is planned to be certified under the Part 23 supplemental type certification of the Caravan retrofit, Noertker says. Used for takeoff and climb, the battery is recharged in flight, eliminating the need for ground charging infrastructure.
“This is the type of hybrid that does not need to be plugged in and because of that everyone in the world can use it regardless of what their energy infrastructure looks like,” he says.
Inflight recharging also avoids deep charge/discharge cycles that consume battery life. “We don’t need to have a large battery. And because of how we use of battery, it’s unlikely to degrade rapidly,” Noertker says. “Every two to three years seems like a good time horizon to be upgrading to new battery technology and that’s well over 2,000 flight cycles.”
Beyond the Caravan, Ampaire is designing H570 retrofits for the Beechcraft King air and De Havilland Twin Otter which, like the Caravan, are powered by the Pratt & Whitney Canada PT6A turboprop. The startup is also developing the 250-kW-class H270, primarily for use as a generator in a distributed electric propulsion system.
Noertker says test data shows the hybrid-electric Caravan will burn 70% less fuel on takeoff, 50% less in cruise and 50% less on aggregate. The retrofit maintains the Caravan’s performance, including capacity for nine passengers and bags, and retains 95% of the volume for cargo while halving fuel cost or doubling aircraft range. It will be capital cost-neutral for a new aircraft compared with the PT6A-powered Caravan.