Commercial

Leonardo Details AW609 Autorotation Sim Efforts for FAA Certification

By Frank Wolfe | November 1, 2018
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Leonardo AW609 Era Group

Era Group becomes launch customer for Leonardo AW609 Era Group. Photo courtesy of Leonardo

Leonardo is laying out the autorotation simulation efforts that the company is pursuing to help gain FAA certification of the AW609 — what is to be the world's first civil tiltrotor.

"Leonardo has chosen to show that it is safe to perform a touchdown autorotation by performing simulated all-engines-inoperative flight at safe altitudes above the ground," Dan Wells, Leonardo's AW609 test pilot, told R&WI Nov. 1. "There is an issue paper with the FAA that discusses this means of compliance. Leonardo has not asked for relief from any autorotation requirement. The issue paper, which will become a matter of public record once it is agreed to all parties, describes the method by which Leonardo will show that the AW609 will be able to perform a safe autorotational landing."

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Because of the unique flying characteristics of the tiltrotor, the FAA is using parts of Federal Regulation CFR 14 Part 29, which governs heavy, transport helicopters, and CFR 14 Part 25, which governs large transport airplanes, in its certification requirements for the AW609.

Part 29 requires that a helicopter can continue flight without undue pilot effort or skill after the loss of all engine power and that it must be possible to make a safe landing to a prepared surface after the loss of all engine power. FAA Advisory Circular 29-2C provides guidance on how to comply with Part 29.

"Several procedures can be utilized to demonstrate compliance with the all engine out landing requirement," according to FAA AC 29-2C. "The intent of this rule is to demonstrate controlled touchdown conditions and freedom from loss of control or apparent hazard to occupants when landing with all engines failed. In these cases, compliance can be demonstrated by leaving throttles in the idle position and assuring no power is delivered to the drive train. Also, computer analysis may be used in conjunction with simulated in-flight checks to give reasonable assurance that an actual safe touchdown can be accomplished. Another method may be to make a power recovery after flare effectiveness of the rotorcraft has been determined. Other methods may be considered if they lead to reasonable assurance that descent can be arrested and forward speed controlled to allow safe landing with no injury to occupants when landing on a prepared surface with all engines failed."

Leonardo wants to avoid possible damage to the AW609 during an in-flight touchdown rotation and thus is pursuing the simulation tack with the FAA. The AW609 simulator has shown the ability of the tiltrotor to land safely with its engines off, Wells said, adding that the AW609 has performed dozens of flight-based autorotations of the AW609, including ones at different centers of gravity and with varying gross weights — autorotations never performed by the V-22 and by the XV-15 only once, he said.

"Leonardo proposes to show compliance [of the AW609] using analysis of actual flown power-off flight and actual flare effectiveness testing that demonstrates the aircraft's ability to achieve acceptable landing criteria (configuration, sink rate, rotor speed, ground speed, control margins, etc.)," Wells said. "This is in keeping with the FAA's guidance as outlined in AC 29-2C."

One possible use of the AW609 could be ferrying small groups of passengers to Manhattan or other major cities without the delays associated with airplane travel, Leonardo has said.

In February, Leonardo said Era Group will be the launch customer for the AW609 and that Era has ordered two 609s for a 2020 entry to service.

Earlier this year, Leonardo said it has received interest from operators for 50 609s.

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