The FAA has published proposed special conditions that apply to the interaction of systems and structures for the Skyryse One supplemental type certificate (STC) program, which aims to certify a fly-by-wire universal operating system in a Robinson R66 helicopter. Skyryse’s Sky OS operating system will also be adapted to a variety of aircraft to meet the company’s goal “to bring about a new era in flight, with a goal of zero fatalities, and where piloting any aircraft is simple and safe.”
As is typically the case with special conditions, the FAA and Skyryse have already spent many months working on what the conditions will cover, and the issuance of the proposal is no surprise to the company. The public is invited to comment on the special conditions and can do so through October 15.
According to a Skyryse spokesman, “We were absolutely aware of this and very happy to see the FAA publishing this special condition rulemaking that's a normal part of the certification process. We've been working closely with the FAA since we received approval on our certification plan in 2019, and we already reviewed and agreed with the FAA's proposed requirements in late 2023. The release of today's special conditions rulemaking is a great milestone showing we're continuing to move towards certification on our expected schedule with the support of an active and engaged FAA team.”
The reason for requiring special conditions is that the modifications that Skyryse is doing to the R66 aren’t covered in existing certification regulations, according to the FAA. The modification includes replacing the R66’s hydraulically boosted mechanical flight control system with fly-by-wire (FBW) flight controls and a single-control pilot interface. “FBW systems are new to part 27 rotorcraft and as such, the rotorcraft [flight control system] will now contain control functions that affect the static strength of rotorcraft structure,” the FAA wrote.
What the proposed special conditions aim to do, the FAA explained, is “give the applicant an option to offset the structural factor of safety based on the probability of system failure. These proposed special conditions apply to systems that can induce loads on the airframe or change the response of the rotorcraft to maneuvers or to control inputs, as a result of failure.” Such systems could include FBW or fly-by-light flight control systems, autopilots, and stability augmentation systems, load-alleviation systems, flutter control systems, fuel management systems, “and other systems that either directly or as a result of failure or malfunction affect structural performance.” Because these systems can operate automatically if they fail they “could impact the loads envelope and rotorcraft static strength.”
The special conditions would ensure that any loads applied during a flight control system malfunction would not be greater than would be the case with the R66’s original flight controls. “To achieve this objective, it is necessary to define the failure conditions with their associated frequency of occurrence in order to determine the structural factors of safety and operating margins that will ensure an acceptable level of safety."
“The proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards,” according to the FAA.
Skyryse aims to receive the STC for the Skyryse One R66 next year. The cost of the FBW upgrade will be about $400,000 more than the $1.4 million price of a new typically equipped R66.
Meanwhile, Skyryse has opened a new facility at Hawthorne Airport in Southern California, where it will conduct Skyryse One installation and repairs. This joins the company’s headquarters in nearby El Segundo and flight test center in Camarillo.