The AW609: Expanding the Vertical Aviation Fleet

Leonardo Helicopters US Photo

After much anticipation, Leonardo Helicopters US appears on the verge of completing its 20-year pursuit of FAA certification for the world’s first certificated civil tiltrotor and putting that aircraft, the AW609, into service with international air services giant Bristow Group.

The manufacturer in recent years stopped forecasting a certification date, but Bill Sunick, Philadelphia, Pennsylvania–based Leonardo’s head of tiltrotor marketing, says “we can definitely see the light at the end of the tunnel.”

For 16 years, the US Marine Corps and the US Air Force Special Operations Command have been flying the AW609’s military predecessor, the Bell Boeing V-22 Osprey, around the globe. Its demonstrated speed, range, and vertical takeoff and landing (VTOL) capabilities have converted tiltrotor skeptics and spurred American military, diplomatic, and humanitarian aid officials to change how they conduct their operations.

Osprey missions have evacuated troops at distances far beyond the reach of single helicopter flights and sped them to faraway hospitals, greatly expanding the Golden Hour’s umbrella for patients. They’ve extended the range and shortened the time to get relief supplies to disaster victims. They’ve enabled the United States to swiftly protect and extract American citizens abroad from harm’s way.

On Oct. 31, 2020, USAF CV-22 Ospreys, paired with Lockheed Martin MC-130Js and other aircraft, flew US Navy SEALs more than 1,500 nm to rescue an American kidnapped along the Niger–Nigeria border. The air force says it was the longest hostage rescue mission flown at night. The mission, requiring flying 11 hours nonstop, was completed within 48 hours. For it, the air force in January 2023 awarded the CV-22 crew members the Distinguished Flying Cross and Air Medals.

In December 2021, the navy made operational its CMV-22B, which is to replace the Northrop Grumman C-2A Greyhound in resupplying aircraft carriers at sea. Navy leaders had resisted employing tiltrotors for that purpose until the mid-2010s.

US Army leaders, likewise, long resisted adopting tiltrotor technology, instead pursuing faster, compound helicopters to speed up vertical lift operations.

Last December, the army awarded Bell $232 million to develop a virtual prototype of its V-280 Valor tiltrotor under the multibillion-­dollar Future Long-Range Assault Aircraft program to replace approximately 2,000 Sikorsky H-60s. (Sikorsky, a Lockheed Martin company, and Boeing, which partnered on the Defiant compound helicopter contender, have protested the award.)

Transforming Civil Vertical Lift

If the 9- to 12-seat AW609 achieves success similar to the V-22 in civil air ambulance, search-and-rescue, offshore support, corporate transport, and VIP operations, it may transform civil vertical lift operations everywhere.

The all-weather tiltrotor is designed to fly at 270 kt. and 25,000 ft. With an 18,000-lb. maximum takeoff weight, 6,000-plus-lb. useful load, and 750-nm range, the fly-by-wire AW609 “is poised to change the face of civil aviation” by giving operators “a huge speed and range advantage over a conventional helicopter,” says David King, Leonardo’s chief engineer for tiltrotor technologies.

The FAA could foster that transformation through its pending review of “powered lift” aircraft regulations. (The term “powered lift” refers to heavier-than-air aircraft that can take off or land like an airplane or a helicopter and transition between both those modes in flight.) In particular, the agency could streamline how pilots are approved to fly the AW609.

Leonardo two years ago opened its Northeast Philadelphia Airport (KPNE) academy to train pilots, among others, for AW609s entering service. The facility includes a Level D flight simulator. But under FAA rules, pilots can’t be cleared to fly a tiltrotor unless they log enough time in such aircraft. The only way to do that currently is to fly military V-22s.

“Training in the two-pilot AW609 requires at least a private powered lift license; no pilot holds one. Today’s ex-military powered lift pilots (roughly 350) hold FAA commercial licenses; high-paying airlines want them. Unless the FAA revises rules, the industry can’t produce nonmilitary commercial powered lift pilots,” says Bryan Willows, Bristow’s AAM program manager. “It’s a showstopper.”

Other hurdles remain. The AW609’s certification goal has been a moving target for years. Its order book has shrunk with those recurring delays, from up to 80 units in the 2000s to an unspecified number today from Bristow, an unnamed European operator, and perhaps the United Arab Emirates. The FAA has pushed back repeatedly on requests for exemptions from regulations that specify “airplanes” or “rotorcraft” with no mention of “powered lift,” a term developed to cover the AW609.

Challenges aside, “we’re looking forward to a big year,” Sunick says. “The AW609 has strong interest around the world in all five mission sets: VIP, corporate, offshore, EMS, and SAR.”

Leonardo has two prototypes flying at its Cascina Costa, Italy, headquarters and another flying in Philadelphia, along with its first production AW609 there. Three customer tilt­rotors are on the Philadelphia production line, including Bristow’s first. The program is racking up flight test hours: 200 or so were logged in 2022’s second half, pushing the total to 1,900-plus, attesting to Sunick’s sentiment that “these are very, very exciting times.”

(In addition to its AW609 activities, the Philadelphia plant assembles the medium twin AW139 and FAA-certificated, multimission MH-139A Grey Wolf that Leonardo is providing, with Boeing, to the US Air Force. The facility also produces the single-engine AW119Kx and the IFR TH-73A navy trainer based on it.)

With COVID’s deadliness fading, the AW609 team has been back on the road. In 2021, Aircraft 4 (N609PH) self-­deployed 2,550 nm from Cascina Costa to visit Expo Dubai and the Dubai Airshow. Last October, Aircraft 3 (N609PA) made the AW609’s National Business Aviation Association (NBAA) debut in Orlando, Florida, with a VIP interior mock-up on exhibit. The team then went to the Association of Air Medical Services conference in Tampa, Florida, exhibiting an air ambulance interior mock-up and meeting with air ambulance operators.

And the team is headed to Atlanta, Georgia, for HAI HELI-EXPO 2023, Mar. 6–9 (exhibits are open Mar. 7–9). At Booth #B1005 at Expo, Leonardo will feature its AW139 and twin-engine AW169, as well as the single-engine AW09. (The company took over the latter aircraft in 2020 when it acquired Kopter AG.)

Regarding an AW609 certification date, Sunick says he “most certainly would scream it from the rooftops” if he could provide one. “We’re having the same challenges every other OEM is: certification throughput challenges with our partners at the FAA, supply chain, and things like that. With the FAA, it’s been a marriage; we’re walking hand in hand, being the first to go down the aisle with the FAA on powered lift.”

Regulatory Criteria in Process

FAA officials caused a stir last May, stating their intention to change how eVTOL (electric vertical takeoff and landing) aircraft would be certificated to carry passengers or freight for hire. eVTOL makers believed, based on earlier FAA guidance, that they could pursue type certificates under Part 23 of the Code of Federal Regulations (CFRs).

Part 23 covers small aircraft and was streamlined in 2017 to speed the incorporation of new technologies. Instead, the FAA said in May that eVTOL aircraft would be approved under CFR 21.17(b), which covers special aircraft classes and requires certificate applicants and the FAA to determine which elements of six different CFRs must be met. AW609 and FAA officials agreed early on in the tiltrotor’s certification efforts that the 21.17(b) “special class” rules would apply.

In November, FAA officials further stirred things up, announcing plans to overhaul the CFRs’ air carrier definition to cover powered lift operations and training. The agency said the proposed changes would be open for public comment and finalized before the first powered lift aircraft was certificated. The rules would be laid out in a Special Federal Aviation Regulation (SFAR), with its draft released mid-2023 and a final version in the second half of 2024.

As of the end of January 2023, however, the FAA hadn’t released the AW609’s final G-1 certification basis for public comment. The agency also hadn’t signed off on the tiltrotor’s type inspection authorization (TIA), a milestone marking the FAA’s completed examination of technical data required for type certification. The TIA clears FAA officials to begin conformity and airworthiness inspections and ground and flight tests needed to fulfill type certificate requirements.

“The FAA will be conducting an early involvement, pre-TIA flight in the very near future,” Sunick says.

Leonardo officials have said they believe “the 609 will be certified with its own certification basis in advance of the SFAR.”

The AW609’s proposed 21.17(b) certification basis draws on airworthiness standards from Parts 29 (Transport Category Rotorcraft), 25 (Transport Category Airplanes), and 23 (Normal Category Airplanes); draft airworthiness standards for powered lift transport aircraft (referred to as Part XX); and unique tiltrotor requirements (referred to as TR).

The Rich History of Tiltrotors

Tiltrotor history goes back at least 90 years, including George Lehberger’s US patent in 1930, though no aircraft was built to that design. By the early 1950s, the US Army and US Air Force jointly researched an aircraft capable of helicopter-like takeoffs and landings but with airplane-fast flight. They used McDonnell Aircraft’s XV-1 compound helicopter but also funded research on two Bell XV-3 tiltrotors through the 1950s. NASA continued that research into the mid-1960s.

NASA’s research prompted its 1972 XV-15 program, under which Bell and Boeing Vertol won contracts for separate designs. Bell’s used rotating engine/gearbox/rotor assemblies in wingtip pods. Boeing’s used stationary engines with rotating rotor pods (like Bell’s new V-280 Valor). NASA chose Bell’s Model 301 tiltrotor for flight tests into the 1980s. Bell and Boeing later teamed up for the US Defense Department’s Joint-Service Vertical Take-off/Landing Experimental (JVX) program, proposing in 1983 an enlarged XV-15, which became the V-22.

In 1994, Bell started the Model D-600 commercial tiltrotor program. Boeing joined it in 1996, launching the Bell Boeing 609. In 1997, Boeing bought McDonnell Douglas, focused on military helicopters, and ended its 609 work. Later that year, Bell brought Agusta into the renamed BA609 development; the latter would manufacture and assemble tiltrotors destined for Europe and elsewhere. Test pilots Roy Hopkins and Dwayne Williams flew the first prototype Mar. 7, 2003, near Bell’s Texas headquarters.

Bell was struggling to sustain its commercial and military helicopter lines, having lost civil ground to Eurocopter and military work to Sikorsky’s H-60s. Meanwhile, the V-22 program was plagued by scandal and problems, including two fatal crashes in 2000 that killed 27 Marines.

Bell sold its BA609 stake in 2011 to Agusta parent Finmeccanica, which set up an arm (now AgustaWestland Philadelphia Corp.) as program owner, technical lead, and type certificate applicant. (Bell is designing and certificating components that it will supply when the AW609 enters production.)

An overhaul of the 609 followed. “We looked at where the aircraft was in its development,” Sunick says. “We talked to a lot of our customers and got a good feeling for what capabilities they were looking for.”

Pratt & Whitney Canada (P&WC) gained certification of a PT6C-67A engine capable of producing 2,000 shaft horsepower (2,500 at one-engine inoperative conditions) and doing so through the proprotor nacelles’ full 95-degree movement arc. The engines can operate continuously in the vertical position. Upgrades included an advanced-aerodynamics compressor and turbines made with state-of-the-art materials that increase power and reduce fuel consumption, P&WC says.

The extra power allowed a maximum takeoff-­weight increase to 18,000 lb. from 16,799 lb. That, in turn, required landing-gear and structural changes. The smaller, side-hinged cabin door was replaced with a 35-in.-wide, 50-in.-high clamshell design, with segments hinged top and bottom. The 609’s changes also included a redesigned cockpit with Pro Line Fusion avionics from Collins Aerospace, a new air data system, upgraded flight control computers, and a new environmental control system.

“We wound up with a whole other development program,” Sunick says. “There’s essentially nothing we didn’t change.”

Preparing for Takeoff

Flight test and certification work are progressing, Sunick notes, including completion of 30-minute run-dry testing of the tilt-axis and proprotor gearboxes.

Aircraft 1 (N609TR), which first flew in 2003, is on a run stand in Italy to verify inspection intervals, check mean time between overhauls, and test rotor- and drive-system endurance.

Aircraft 2 (N609AG) had been used for the development of new installations (such as a new pitot-static system), marketing flights, and collaborative development with Bristow of an offshore support configuration. It broke up in flight on Oct. 30, 2015, over northern Italy, killing test pilots Herb Moran and Pietro Venanzi. The two pilots had detected roll oscillations during a maximum dive-speed test at 293 kt. Italy’s Agenzia Nazionale per la Sicurezza del Volo (National Agency for the Safety of Flight) found that, as designed, the flight control system generated yaw inputs to counteract the sideslip effects of the pilot flying’s roll input. This led to divergent oscillations, likely causing the right proprotor blades to strike the right-wing leading edge.

Aircraft 3 is conducting engine-handling performance and load-level surveys in Philadelphia. It had been used for icing certification tests in Michigan.

Aircraft 4 is being used for mechanical-systems and avionics testing in Italy and will conduct customer demonstrations.

Aircraft 5 (N609LH), the first production AW609, has been used for ground-based high-intensity radiated field and indirect-effects-of-lightning tests. It will participate in mission capability assessments and customer demonstrations, support the transition from development to operations, and assist with FAA type and production certificate examinations.

The Philadelphia operation has registered a sixth AW609, whose tail number, N609LE, was issued by the FAA on Aug. 4, 2022.

At HAI HELI-EXPO 2023, Sunick says he’ll be assessing customers’ familiarity with the tiltrotor. “Like the V-22, getting folks in the airframe, flying it, showing it, demonstrating missions helps open their eyes to possibilities for their operation,” he says.

That, adds Sunick, sparks in potential customers that eureka moment when the promise of this exciting aircraft becomes clear.