Rules and Regulations. Final special conditions; request for comments

Agency: Federal Aviation Administration (FAA), DOT
Action: Final special conditions; request for comments
Citation: FR Doc. 2017-25019 · Docket No. FAA-2017-0951; Special Conditions No. 25-706-SC · 14 CFR 25

Summary

These special conditions are issued for Mitsubishi Aircraft Corporation (Mitsubishi) Model MRJ-200 airplanes. These airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. This design feature is an electronic flight-control system (EFCS) that provides control of the airplane through pilot inputs to the flight computer. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These 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.

Dates

This action is effective on Mitsubishi on November 22, 2017. We must receive your comments January 8, 2018.

Supplementary Information

The FAA has determined that notice of, and opportunity for prior public comment on, these special conditions is unnecessary because the substance of these special conditions has been subject to the public-comment process in several prior instances with no substantive comments received. The FAA finds good cause that prior notice and comment are unnecessary, and for the same reason finds that good cause exists for adopting these special conditions upon publication in the Federal Register . Comments Invited The FAA is requesting comments to allow interested persons to submit views that may not have been submitted in response to the prior opportunities for comment described above. We invite interested people to take part in this rulemaking by sending written comments, data, or views. The most helpful comments reference a specific portion of the special conditions, explain the reason for any recommended change, and include supporting data. We will consider all comments we receive by the closing date for comments. We may change these special conditions based on the comments we receive. Background On August 19, 2009, Mitsubishi applied for a type certificate for their new Model MRJ-200 airplane. The Model MRJ-200 airplane is a low-wing, conventional-tail design with two wing-mounted turbofan engines. The airplane is equipped with an electronic flight-control system, has seating for 96 passengers and a maximum takeoff weight of 98,800 lbs. Type Certification Basis Under the provisions of title 14, Code of Federal Regulations (14 CFR) 21.17, Mitsubishi must show that the Model MRJ-200 airplane meets the applicable provisions of part 25, as amended by Amendments 25-1 through 25-141; part 36, as amended by Amendments 36-1 through 36-30; and part 34, as amended by Amendments 34-1 through the amendment effective at the time of design approval. If the Administrator finds that the applicable airworthiness regulations ( i.e., 14 CFR part 25) do not contain adequate or appropriate safety standards for the Model MRJ-200 airplane 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 type certificate for that model be amended later to include any other model that incorporates 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 model MRJ-200 airplane 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 § 21.17(a)(2). Novel or Unusual Design Features The Model MRJ-200 airplane will incorporate the following novel or unusual design feature: An electronic flight-control system that provides control of the airplane through pilot inputs to the flight computer. Current part 25 airworthiness regulations account for control laws where aileron deflection is proportional to control-stick deflection. They do not address any nonlinearities, i.e., situations where output does not change in the same proportion as input, or other effects on aileron actuation that may be caused by electronic flight controls. Discussion The flight-control system for the Model MRJ-200 airplane does not have a direct mechanical link, nor a linear gain, between the airplane flight-control surface and the pilot's flight-deck control device, which is not accounted for in § 25.349(a). Instead, a flight-control computer commands the airplane flight-control surfaces, based on input received from the flight-deck control device. The flight-control computer modifies pilot input before the command is given to the flight-control surface. These special conditions differ from current regulatory requirements in that they require that the roll maneuvers result from defined movements of the flight-deck roll control as opposed to defined aileron deflections. Also, these special conditions require an additional load condition at design maneuvering speed (V ^A ), in which the flight-deck roll control is returned to neutral following the initial roll input. These special conditions differ from similar special conditions previously issued on this topic. These special conditions are limited to the roll axis only, whereas other special conditions also included pitch and yaw axes. Special conditions are no longer needed for the yaw axis because § 25.351 was revised at Amendment 25-91 to take into account effects of an electronic flight-control system. No special conditions are needed for the pitch axis because the method that Mitsubishi proposed for the pitch maneuver takes into account effects of an electronic flight-control system. These 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. Applicability As discussed above, these special conditions are applicable to the Model MRJ-200 airplanes. Should Mitsubishi apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design feature, these special conditions would apply to that model as well. Conclusion This action affects only certain novel or unusual design features on one model of airplanes. It is not a rule of general applicability. List of Subjects in 14 CFR Part 25 Aircraft, Aviation safety, Reporting and recordkeeping requirements. The authority citation for these special conditions is as follows: Authority: 49 U.S.C. 106(g), 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 Mitsubishi Model MRJ-200 airplanes. In lieu of compliance to 14 CFR 25.349(a), the following conditions, speeds, and flight-deck roll-control motions (except as the motions may be limited by pilot effort) must be considered in combination with an airplane load factor of zero, and of two-thirds of the positive maneuvering factor used in design. In determining the resulting control-surface deflections, the torsional flexibility of the wing must be considered in accordance with § 25.301(b). (a) Conditions corresponding to steady rolling velocities must be investigated. In addition, conditions corresponding to maximum angular acceleration must be investigated for airplanes with engines or other weight concentrations outboard of the fuselage. For the angular acceleration conditions, zero rolling velocity may be assumed in the absence of a rational time-history investigation of the maneuver. (b) At V ^A , sudden movement of the flight-deck roll control up to the limit is assumed. The position of the flight-deck roll control must be maintained until a steady roll rate is achieved, and then must be returned suddenly to the neutral position. (c) At V ^C , the flight-deck roll control must be moved suddenly and maintained so as to achieve a roll rate not less than that obtained in special condition (b). (d) At V ^D , the flight-deck roll control must be moved suddenly and maintained so as to achieve a roll rate not less than one third of that obtained in special condition (b). Victor Wicklund, Manager, Transport Standards Branch, Policy and Innovation Division, Aircraft Certification Service. [FR Doc. 2017-25019 Filed 11-21-17; 8:45 am]