Tier 1 Engineering is one of the pioneers of electric vertical flight and the only company in the world that’s been regularly flying a piloted electric helicopter since 2016 as part of its development program.
The company’s first proof-of-concept e-R44 (N3115T) incorporating off-the-shelf components and a 1,100-lb (500-kg) battery pack flew on Sept. 13, 2016, at Joint Forces Training Base Los Alamitos in Southern California. In 2018, Tier 1 claimed the Guinness World Record for the farthest distance traveled by an electric helicopter, more than 30 nm (55 km) at an average speed of 80 kt (148 km/h).
Tier 1 founder Glen Dromgoole has been focused on the fastest and easiest path to certify an electric rotorcraft after concluding that the work and cost involved in certifying a clean sheet aircraft design would scale significantly if electric propulsion was added to the task list. Instead, Tier 1 is developing an electric propulsion system that can be easily installed in a proven airframe like the R44 by way of a Federal Aviation Administration (FAA) approved supplementary type certificate (STC).
Aviation innovators have long used STCs to upgrade existing aircraft with new powerplants to enhance payload, speed, reliability and safety.
Examples from the helicopter world include turboshaft upgrade programs for the piston-powered Sikorsky S-55, S-58, Bell 47 and Hiller UH-12, which received STC approvals in the 1970s. This was followed by the use of STCs to install the Safran (Turbomeca) Arriel 1S and 1S1 turboshafts in the S-76A+ and S-76A++, and the Rolls-Royce (Allison) 250-C20B in the Soloy AllStar Airbus 350B and 350D in the mid-1980s. More recently, Eagle Copters received an STC for installing the Honeywell HTS900D-2-1D in the “Hot and High” Bell 407HP in 2015.
In 2018, Tier 1 decided to focus on the in-house development of the battery pack, electric motor, motor controller and pilot interface, which are the key components of the electric-propulsion system.
Despite delays caused by COVID-19 restrictions, Tier 1 flew its second-generation e-R44 (N484AK) for the first time at Los Alamitos on July 26, 2021, with a new battery pack that weighed 300 lb (135 kg) less than the original design — i.e., only 800 lb (360 kg) with the same power and endurance (see “Tier 1 Engineering Reveals Its Second Battery-Electric Robinson R44 Helicopter,” Vertiflite, Sept/Oct 2021). The weight reduction was achieved by using higher energy density cells, improving pack design and designing a new lightweight and streamlined structure to support the cells.
A new electric motor was also developed with a partner but did not perform as expected, so Tier 1 decided to work with a new supplier: Tier 1 announced on Dec. 7 that it had selected magniX’s electric-propulsion units.
“magniX was chosen as they are leading the industry in the development of aviation-specific electric propulsion, and we recognized that significant progress had been made towards obtaining FAA certification. With magniX’s technology, we are now much closer to obtaining STC approval of the e-R44 and transforming the delivery of life-saving human organs,” said Dromgoole in a press release.
On Dec. 2, Tier 1 Engineering took delivery of the first magniX motor (a prototype magni250) and inverter, at its Santa Ana, California facility. The magniX motors have been used in all-electric aircraft since the first flight of a retrofitted Harbour Air DHC-2 Beaver in Vancouver, British Columbia, in December 2019 and the company is considered a market leader on the path to FAA Part 33 certification (“Airworthiness Standards: Aircraft Engines”) following the recent publication of the Special Conditions for certification of the magni250 and magni350 motors from the FAA (see “Electric VTOL News: FAA Issues MagniX Certification Requirements,” Vertiflite, Nov/Dec 2021).
The FAA says that “a supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received FAA approval to modify an aeronautical product from its original design. The STC, which incorporates by reference the related TC, approves not only the modification but also how that modification affects the original design.”
This means Tier 1 must develop in-depth knowledge of the R44 (since Robinson Helicopter Co. is not participating in the STC program) to support the safe integration and operation of the helicopter, while magniX’s leads the FAR 33 certification of the engine. To this end, the company has acquired a new R44 that will be used to benchmark the performance and flight characteristics of the piston aircraft.
Dromgoole says Tier 1 should complete the integration of the magniX engine into its propulsion system by late 2021 with plans to fly its third-generation e-R44 in early 2022. This will be the company’s original e-R44 (N3115T), which is being stripped of its original motor to accommodate the new system.
Meanwhile, flight testing continues on the second aircraft that has recently been overhauled and retrofitted with a new interior to meet Lung Biotechnology PBC organ delivery requirements. The work also allowed Tier 1 to better understand the work involved in retrofitting an R44 with a new motor and interior once the STC is approved retrofits begin for its launch customers.
Part 33 certification of the magniX motor will now pace the timing of Tier 1 receiving its STC for the e-R44.
Tier 1 also has a contract to deliver a limited number of e-R44s for charter use by Eco Helicopters, which is being established by Ric Webb, who has test-piloted all the e-R44 flights.
Tier 1 is an active participant in discussions with the FAA and industry consensus groups — e.g. the General Aviation Manufacturers Association (GAMA), SAE International, ASTM International, etc. — that have been trying to address the certification requirements for an electric propulsion system and, more significantly, the means of compliance.
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