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 proposed 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, and will consider comments filed late if it is possible to do so without incurring delay. The FAA may change these special conditions based on the comments received.

Privacy

Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in title 14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all comments received without change to www.regulations.gov, including any personal information you provide. The FAA will also post a report summarizing each substantive verbal contact received about these special conditions.

Confidential Business Information

Confidential Business Information (CBI) is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to these special conditions contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to these special conditions, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and the indicated comments will not be placed in the public docket of these proposed special conditions. Send submissions containing CBI to the individual listed in the For Further Information Contact section above. Comments the FAA receives, which are not specifically designated as CBI, will be placed in the public docket for these proposed special conditions.

Background

On December 5, 2021, Embraer applied for a change to Type Certificate No. A57NM to add a functionality known as E² TS in the Model ERJ 190-400 series airplane. The Embraer Model ERJ 190-400 series airplane is a twin-engine, transport category airplane with a maximum passenger capacity of 146, and a maximum takeoff weight of 135,584 pounds.

Type Certification Basis

Under the provisions of 14 CFR 21.101, Embraer must show that the changes to the Embraer Model ERJ 190-400 series airplane continue to meet the applicable provisions of the regulations listed in Type Certificate No. A57NM or the applicable regulations in effect on the date of application for the change, except for earlier amendments as agreed upon by the FAA.

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 Embraer Model ERJ 190-400 series 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 ( printed page 67531) for that model be amended later to include any other model that incorporates the same novel or unusual design feature, or should any other model already included on the same type certificate be modified 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 Embraer Model ERJ 190-400 series airplane must comply with the 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 14 CFR 11.38, and they become part of the type certification basis under § 21.101.

Novel or Unusual Design Features

The Embraer Model ERJ 190-400 series airplane will incorporate the following novel or unusual design feature:

The Embraer ERJ 190-400 airplane will have a functionality known as Embraer Enhanced Takeoff System (E² TS), a function which automatically controls the airplane's pitch and bank angle without pilot input to the airplane controls.

Discussion

E² TS is an autoflight function specifically designed to improve takeoff performance and enhance operational safety. It is engaged at the beginning of the takeoff roll, when the thrust levers are advanced to the takeoff go-around (TOGA) detent. Upon engagement, the airplane control in pitch—including the takeoff rotation maneuver and initial climb-out—will be automatically performed, without any pilot intervention. Control of the bank angle will also be automatically performed by E² TS, maintaining wings level while the airplane is on the ground and the directional tracking when the airplane is in the air. During the ground run, the flight crew is responsible for maintaining runway centerline via manual directional control, with augmentation provided by the E² TS to minimize heading deviations.

Once the airplane is airborne, E² TS provides control using sideslip as the reference. If all engines are operating (AEO), zero sideslip is the reference; if one engine is inoperative (OEI), then the Best Beta is considered as the sideslip reference. It is noted that any flight crew intervention on the rudder pedal is summed with the rudder controls that are output by the E² TS mode.

Takeoff performance requirements of 14 CFR part 25 require the ability to safely complete the takeoff or bring the airplane to a complete stop in a rejected takeoff. As written, the takeoff performance requirements presuppose manual flying with a human pilot onboard making certain decisions and taking action. In fact, paragraph 4.4.5.1 of AC 25-7D reads: “The rotation speed, V_R, is intended to be the speed at which the pilot initiates action to raise the nose wheel(s) off the ground during the acceleration to V₂.” The current regulations do not take into consideration that the takeoff rotation is being performed by an automatic system, not a human being.

These special conditions specifically address paragraphs 25.107(e)(3) and (e)(4), which deal with human pilot variability effects in flying the airplane (formerly called “takeoff abuse tests”). That is, instead of considering the “reasonably expected variations in service” of the original rules, one should now consider “maximum expected deviations” due to sensor accuracy and system tolerances.

Furthermore, for E² TS operation, V_R is the speed at which this system will perform the rotation, and the speed the pilot will use to monitor the automatic rotation. Determination of “maximum expected deviations of V_R ” should reflect “in-service” variations and may be done using a combination of analyses, simulations, and certification flight tests, including, but not limited to, performance and handling qualities tests. Such analyses will result in a deviation that should ensure a level of safety equivalent to or higher than operational flights with conventional takeoffs (manual takeoff with pilot in the loop).

Lastly, to ensure consistency between flight test demonstrations and actual, in-service operations, compliance with 14 CFR 25.101 must be shown, especially paragraphs 25.101(d), (e), (f), and (h).

When demonstrating compliance with these special conditions, the following guidance applies:

• The FAA understands that the automatic rotation provided by E² TS function is expected to reduce rotation variabilities as human piloting variabilities will not be present. Paragraph 25.107(e)(1)(iv) requires an airplane “maximum practicable rate” rotation maneuver. However, sensor inaccuracies and system tolerances will still be present and should be considered as residual variabilities. These residual variabilities should be evaluated in the operational envelope (considering weight, CG, thrust, altitude, temperature, and wind) in a manner that the V_LOF /V_MU required margins from 25.107(e)(1)(iv) can be met considering the maximum expected deviations on V_LOF.
• Any demonstrations required to show compliance to these special conditions should consider the operational envelope (i.e., weight, CG, thrust, altitude, temperature, and winds) in a manner that the required margins on Airplane Flight Manual (AFM) takeoff distance can be met considering the maximum expected deviations. Performance testing should be executed in limited wind conditions and calculations should assume no wind gusts. Wind gusts need not be considered in demonstrations for compliance with these special conditions.

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.

Applicability

As discussed above, these proposed special conditions are 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, or should any other model already included on the same type certificate be modified to incorporate the same novel or unusual design feature, these special conditions would apply to the other 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.

Authority Citation

The authority citation for these special conditions is as follows:

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

The Proposed Special Conditions

Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for Embraer Model ERJ 190-400 series airplanes.

(a) In lieu of compliance with 25.107(e)(3), for automatic takeoff systems, the one-engine inoperative takeoff distance, accounting for the maximum expected deviation of V_R allowed by E² TS, must not exceed the ( printed page 67532) corresponding AFM takeoff distance established in accordance with § 25.113(a)(1).

(b) In lieu of compliance with 25.107(e)(4), for automatic takeoff systems, accounting for the maximum expected deviation of V_R allowed by E² TS, or in out-of-trim conditions, the all-engines-operating takeoff distance must not exceed the corresponding AFM takeoff distance, established in accordance with § 25.113(a), by more than 1%. Deviations of other parameters that might influence pitch rotation dynamics ( e.g., pitch angle, pitch rate) must be accounted for, unless the effect of such deviations on the takeoff distance is shown to be negligible.

(c) Operation of the E2TS function must not result in unsafe flight characteristics.

91 FR 67530