SUPPLEMENTARY INFORMATION:

Background

On April 10, 2023, Skyryse applied for a supplemental type certificate (STC) for replacing the current mechanical primary flight controls with an FBW flight control system (FCS) in the Robinson Model R66 helicopter. The Robinson Model R66 helicopter, currently approved under Type Certificate No. R00015LA, is a single engine normal category rotorcraft with a maximum takeoff weight of 2,700 pounds and a maximum seating capacity of five passengers. The Model R66 is a single pilot helicopter approved for day and night operations under visual flight rules (VFR) only.

Section 27.695 was issued in 1964 for rotorcraft with rudimentary mechanical ( printed page 52003) systems. The state of technology at that time provided no basis for a digital replacement. Skyryse is proposing to replace the current mechanical primary flight controls on the Model R66 helicopter with a digital FBW FCS. Because of the loss of pilot awareness that would have been provided by mechanical system feedback to the cyclic, an annunciation requirement is necessary through these special conditions.

Type Certification Basis

Under the provisions of 14 CFR 21.101, Skyryse must show that the Robinson Model R66 helicopter, as changed, continues to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. R00015LA or the applicable regulations in effect on the date of application for the change.

If the Administrator finds that the applicable airworthiness regulations ( i.e.,14 CFR part 27) do not contain adequate or appropriate safety standards for the Robinson Model R66 helicopter because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.

Special conditions are initially applicable to the model for which they are issued. Should the applicant apply for an STC to modify any other model included on the same type certificate to incorporate the same novel or unusual design feature, these special conditions would also apply to the other model under § 21.101.

In addition to the applicable airworthiness regulations and special conditions, the Robinson Model R66 helicopter must comply with the fuel-vent and exhaust-emission requirements of 14 CFR part 34, and the noise-certification requirements of 14 CFR part 36.

The FAA issues special conditions, as defined in 14 CFR 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 21.101.

Novel or Unusual Design Features

The Robinson Model R66 helicopter would incorporate the following novel or unusual design feature:

A primary FCS that replaces the mechanical cyclic and collective with an FBW FCS. Skyryse applied for a supplemental type certificate for a system with aircraft-agnostic flight automation technology, the SkyOS, in Robinson Model R66 rotorcraft. The flight control inputs from this FBW system will replace the tactical feedback from pushrods with a position calculated by a computer. The SkyOS does not modify the engine, main rotor, tail rotor, or physical travel limits of the flight control surfaces.

Discussion

The 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. The special conditions are required to address the gap in the regulation that was created by the replacement of mechanical primary flight control with digital controls. Section 27.695 is based on the ability of the pilot to manage control of the rotorcraft with tactile feedback, which does not exist in the proposed FBW design. As such, to provide the same level of safety, these special conditions would require a display of the commanded positions of the primary flight controls and any information regarding the FBW system state of operation.

The 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.

Discussion of Comments

The FAA issued Notice of Proposed Special Conditions No. 27-26-01-SC for the Robinson Model R66 helicopter, which was published in the Federal Register on April 21, 2026 (91 FR 21268). One commenter stated general disagreement without explanation and without requesting a change to the proposed special conditions.

The special conditions are adopted as proposed.

Applicability

As discussed above, these special conditions are applicable to the Robinson Model R66 helicopter. Should Skyryse apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. R00015LA to incorporate the same novel or unusual design feature, these special conditions would apply to that model as well.

Conclusion

This action affects only a certain novel or unusual design feature on one helicopter model. It is not a rule of general applicability and affects only the applicant who applied to the FAA for approval of these features on the helicopter.

Authority Citation

The authority citation for these special conditions is as follows:

Authority: 49 U.S.C. 106(f), 40113, 44701, 44702, 44704.

The Special Conditions

Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the type certification basis for the Robinson Helicopter Company (Robinson) Model R66 helicopter, as modified by Skyryse.

Flight Control Systems

The flight control system functions, controls, indications, and alerts must be designed to minimize flightcrew errors and confusion concerning operation of the flight control system. This includes any degraded functions required for continued safe flight and landing. Means must be provided to indicate the current mode of operation to the pilot. The controls and indications must be grouped and presented to the pilot in a format that clearly defines the flight control system functions. The displayed information must be visible to the flightcrew under all expected lighting conditions.

91 FR 52002