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Federal Register / Vol. 86, No. 56 / Thursday, March 25, 2021 / Rules and Regulations The substance of these special conditions has been published in the Federal Register for public comment in several prior instances with no substantive comments received. Therefore, the FAA
has determined that prior public notice and comment are unnecessary, and finds that, for the same reason, good cause exists for adopting these special conditions upon publication in the Federal Register.

SUPPLEMENTARY INFORMATION:

Comments Invited The FAA invites 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.
The FAA will consider all comments received by the closing date for comments. The FAA may change these special conditions based on the comments received.
Background On March 3, 2015, MITAC applied for a type certificate for their new Model MRJ200 airplane. This airplane is a twin-engine, transport-category airplane with seating for 92 passengers and a maximum takeoff weight of 98,767
pounds.
Type Certification Basis Under the provisions of title 14, Code of Federal Regulations 14 CFR 21.17, the applicant must show that the airplane meets the applicable provisions of 14 CFR part 25, as amended by amendments 251 through 25141.
If the Administrator finds that the applicable airworthiness regulations e.g., 14 CFR part 25 do not contain adequate or appropriate safety standards for the MITAC Model MRJ200 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 MITAC Model MRJ200
airplane must comply with the fuel-vent and exhaust-emission requirements of 14 CFR part 34, and the noise-

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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 21.17a2.
Novel or Unusual Design Features The MITAC Model MRJ200 airplane will incorporate the following novel or unusual design feature:
An Automatic Takeoff Thrust Control System, referred to as an Automatic Power Reserve, to set the performance level for approach-climb operation after an engine failure.
Discussion MITAC included an APR system an ATTCS in the Model MRJ200 airplane and proposed using the APR function during go-around. They also requested approach-climb performance credit for the use of additional thrust set by the APR system. The MITAC Model MRJ
200 powerplant control system comprises a Full Authority Digital Engine Control FADEC for the engine.
The engine FADEC system utilizes the APR function during the takeoff and goaround phases of the flight when additional thrust is needed from an operating engine following a single engine failure. The APR system is available at all times, without any additional action from the pilot. It allows the pilot to use the same powersetting procedure during a go-around regardless of whether or not an engine fails. Because the APR system is always armed, it will function automatically following an engine failure, and advance the remaining engine to a higher thrust level.
The part 25 standards for ATTCS, contained in 25.904, and appendix I to part 25, specifically restrict performance credit for ATTCS to takeoff. Expanding the standards to include other phases of flight, including go-around, was considered at the time the standards were issued, but flightcrew workload issues precluded further consideration.
As the preamble of amendment 2562
states:
In regard to ATTCS credit for approach-climb and go-around maneuvers, current regulations preclude a higher power for the approach climb 25.121d than for the landing climb 25.119. The workload required for the flightcrew to monitor and select from multiple in-flight power settings in the event of an engine failure during a critical point in the approach, landing, or go-around operations is excessive.
Therefore, the amendment should not
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include the use of ATTCS for anything except the takeoff phase.
Because the airworthiness regulations do not contain appropriate safety standards to allow approach-climb performance credit for ATTCS, special conditions are required to ensure a level of safety equivalent to that established in the regulations. The definition of a critical time interval for the approachclimb case, during which time it must be extremely improbable to violate a flight path based on the 25.121d gradient requirement, is of primary importance. In the event of a simultaneous failure of both an engine and the APR function, falling below the minimum flight path defined by the 2.5degree approach, decision height, and climb gradient required by 25.121d must be shown to be an extremely improbable event during this critical time interval. The 25.121d gradient requirement implies a minimum oneengine-inoperative flight path capability with the airplane in the approach configuration. The engine may have been inoperative before initiating the goaround, or it may become inoperative during the go-around. The definition of the critical time interval must consider both possibilities.
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 MITAC
Model MRJ200 airplane. Should MITAC 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 a certain novel or unusual design feature 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.
Authority Citation The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106f, 106g, 40113, 44701, 44702, 44704.

The Special Conditions Accordingly, pursuant to the authority delegated to me by the
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