This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

75513 

Vol. 88, No. 212 

Friday, November 3, 2023 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2021–1032; Notice No. 25– 

23–03–SC] 

Special Conditions: Airbus Model 

A321neo XLR Airplanes; Flight 

Envelope Protection, Icing and NonIcing Conditions; High Incidence 

Protection. 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed special 

conditions. 

SUMMARY: This action proposes special 

conditions for the Airbus Model 

A321neo XLR airplane. The airplane 

will have a novel or unusual design 

feature when compared to the state of 

technology envisioned in the 

airworthiness standards for transportcategory airplanes. This design feature 

is associated with flight-envelope 

protections, in icing and non-icing 

conditions, that use high-incidence 

protection and an alpha-floor system to 

automatically advance throttles when 

the airplane angle of attack reaches a 

predetermined value. 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: Send comments on or before 

December 4, 2023. 

ADDRESSES: Send comments identified 

by Docket No. FAA–2021–1032 using 

any of the following methods: 

Federal eRegulations Portal: Go to 

https://www.regulations.gov/ and follow 

the online instructions for sending your 

comments electronically. 

Mail: Send comments to Docket 

Operations, M–30, U.S. Department of 

Transportation (DOT), 1200 New Jersey 

Avenue SE, Room W12–140, West 

Building Ground Floor, Washington, DC 

20590–0001. 

Hand Delivery or Courier: Take 

comments to Docket Operations in 

Room W12–140 of the West Building 

Ground Floor at 1200 New Jersey 

Avenue SE, Washington, DC, between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. 

Fax: Fax comments to Docket 

Operations at 202–493–2251. 

Docket: Background documents or 

comments received may be read at 

https://www.regulations.gov/ at any 

time. Follow the online instructions for 

accessing the docket or go to Docket 

Operations in Room W12–140 of the 

West Building Ground Floor at 1200 

New Jersey Avenue SE, Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

FOR FURTHER INFORMATION CONTACT: Troy 

Brown, Performance and Environment 

Unit, AIR–621A, Technical Policy 

Branch, Policy and Standards Division, 

Aircraft Certification Service, Federal 

Aviation Administration, 1801 S. 

Airport Rd., Wichita, KS 67209–2190; 

telephone and fax 405–666–1050; email 

troy.a.brown@faa.gov. 

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. 

Certification of the Airbus Model 

A321neo XLR airplane is currently 

scheduled for December 2023. The 

substance of these special conditions, in 

all material respects, has been subject to 

the notice and public-comment 

procedure in several prior instances. 

Therefore, because a delay would 

significantly affect the applicant’s 

installation of the novel or unusual 

design feature, and delay certification of 

the airplane, the FAA is reducing the 

public-comment period to 30 days. 

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 https://

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 special 

conditions. Send submissions 

containing CBI to the individual listed 

in the FOR FURTHER INFORMATION

CONTACT section below. Comments the 

FAA receives, which are not specifically 

designated as CBI, will be placed in the 

public docket for these special 

conditions. 

Background 

On September 16, 2019, Airbus 

applied for an amendment to Type 

Certificate No. A28NM to include the 

new Model A321neo XLR airplane. 

These airplanes are twin-engine, 

transport-category airplanes with 

seating for 244 passengers and a 

maximum take-off weight of 222,000 

pounds. 

Type Certification Basis 

Under the provisions of 14 CFR 

21.101, Airbus must show that the 

Model A321neo XLR airplane meets the 

applicable provisions of the regulations 


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listed in Type Certificate No. A28NM, 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 Airbus Model A321neo XLR 

airplanes 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, 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 Airbus Model A321neo 

XLR 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 § 11.19, in accordance with 

§ 11.38, and they become part of the 

type certification basis under 14 CFR 

21.101. 

Novel or Unusual Design Features 

The Airbus Model A321neo XLR 

airplane will incorporate the following 

novel or unusual design feature: 

Flight-envelope protections, in icing 

and non-icing conditions, that use highincidence protection and an alpha-floor 

function to automatically advance 

throttles when the airplane angle of 

attack (AoA) reaches a predetermined 

value. 

Discussion 

The current airworthiness standards 

do not contain adequate safety 

standards for the high-incidence 

protection system and the alpha-floor 

system for the Airbus Model A321neo 

XLR series airplanes. This is because the 

current standards were designed for 

more traditional electronic flight control 

systems (EFCS), which involve less 

advanced envelope protections, such as 

stick shakers and pushers. These special 

conditions address the more advanced 

flight envelope protections, including 

icing and non-icing conditions, that are 

part of the EFCS design of the A321neo 

XLR airplane. 

The high-incidence protection system 

prevents the airplane from stalling and, 

therefore, the stall warning system is not 

needed during normal flight conditions. 

However, during failure conditions, 

which are not shown to be extremely 

improbable, the requirements of 14 CFR 

25.203 and 25.207 apply, although 

slightly modified. If there are failures 

not shown to be extremely improbable, 

the flight characteristics at the angle-ofattack for CLMAX must be suitable in the 

traditional sense, and stall warning 

must be provided in a conventional 

manner-. These special conditions 

address the need for modification 

during icing conditions and non-icing 

conditions. 

The alpha-floor function 

automatically advances the throttles on 

the operating engines under flight 

circumstances of low speed if the 

airplane reaches a predetermined high 

AoA. This function is intended to 

provide increased climb capability. 

These special conditions address 

these novel or unusual design features 

on the Airbus Model A321neo XLR and 

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 apply to Airbus Model 

A321neo XLR airplane. Should Airbus 

apply later for a change to the type 

certificate to include another model 

incorporating the same novel or unusual 

design feature, the special conditions 

would apply to that model as well. 

Conclusion 

This action affects only certain novel 

or unusual design features on one model 

series 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. 106(f), 106(g), 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 Airbus 

Model A321neo XLR airplane. These 

special conditions are issued in lieu of 

the paragraphs of 14 CFR part 25 

referenced below. 

Foreword 

In the following paragraphs, ‘‘In icing 

conditions’’ means with the ice 

accretions, relevant for the flight phase, 

as defined in part 25, amendment 121, 

appendix C. 

(a) Definitions 

These special conditions address 

novel or unusual design features of the 

Airbus A321neo XLR and use 

terminology that does not appear in part 

25. For the purpose of these special 

conditions, the following terms describe 

certain aspects of these novel or unusual 

design features: 

High-Incidence Protection System 

Angle-of-Attack Limiting Function 

A system that operates directly and 

automatically on the airplane’s flying 

controls to limit the maximum angle of 

attack (AoA) that can be attained to a 

value below that at which an 

aerodynamic stall would occur. 

Alpha-Floor System 

A system that automatically increases 

thrust on the operating engines when 

AoA increases through a particular 

value. 

Alpha Limit 

The maximum angle of attack at 

which the airplane stabilizes with the 

high-incidence protection system 

operating and the longitudinal control 

held on its aft stop. 

VCLmax

An airspeed calculated from a variety 

of factors, including load factor normal 

to the flight path at VCLmax, airplane 

gross weight, aerodynamic reference 

wing area, and dynamic pressure. 

Vmin

The minimum steady flight speed in 

the airplane configuration under 

consideration with the high-incidence 

protection system operating. 

Vmin1g

Vmin corrected to 1g conditions. This 

is the minimum calibrated airspeed at 

which the airplane can develop a lift 

force normal to the flight path and equal 

to its weight when at an angle of attack 

not greater than that determined for 

Vmin. 

(b) Capability and Reliability of the 

High-Incidence Protection System 

Acceptable capability and reliability 

of the high-incidence protection system 

can be established by flight test, 

simulation, and analysis, as appropriate. 


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The capability and reliability required 

are as follows: 

(1) It must not be possible, during 

pilot-induced maneuvers, to encounter a 

stall; and handling characteristics must 

be acceptable, as required by condition 

(e) of these Special Conditions. 

(2) The airplane must be protected 

against stalling due to the effects of 

wind-shears and gusts at low speeds as 

required by condition (f) of these 

Special Conditions. 

(3) The ability of the high-incidence 

protection system to accommodate any 

reduction in stalling incidence must be 

verified in icing conditions. 

(4) The high-incidence protection 

system must be provided in each 

abnormal configuration of the high-lift 

devices that are likely to be used inflight following system failures. 

(5) The reliability of the system and 

the effects of failures must be acceptable 

in accordance with § 25.1309. 

(c) Minimum Steady Flight Speed and 

Reference Stall Speed 

In lieu of § 25.103, minimum steady 

flight speed and reference stall speed, 

the following requirements apply: 

(1) The minimum steady flight speed, 

Vmin, is the final stabilized calibrated 

airspeed obtained when the airplane is 

decelerated until the longitudinal 

control is on its stop in such a way that 

the entry rate does not exceed 1 knot per 

second. 

(2) The minimum steady flight speed, 

Vmin, must be determined in icing and 

non-icing conditions with: 

(i) The high-incidence protection 

system operating normally; 

(ii) Idle thrust and alpha-floor system 

inhibited; 

(iii) All combinations of flaps setting 

and landing gear position for which Vmin

is required to be determined; 

(iv) The weight used when the 

reference stall speed, VSR, is being used 

as a factor to determine compliance 

with a required performance standard; 

(v) The most unfavorable center of 

gravity allowable; and 

(vi) The airplane trimmed for straight 

flight at a speed achievable by the 

automatic trim system. 

(3) The 1g minimum steady flight 

speed, Vmin1g, is the minimum calibrated 

airspeed at which the airplane can 

develop a lift force (normal to the flight 

path) equal to its weight, while at an 

angle of attack not greater than that at 

which the minimum steady flight speed 

of condition (c)(1), above, was 

determined. It must be determined in 

icing and non-icing conditions. 

(4) The reference stall speed, VSR, is 

a calibrated airspeed the applicant 

defines. VSR may not be less than a 1g 

stall speed. VSR must be determined in 

non-icing conditions and expressed as: 

Where: 

VCLmax = Calibrated airspeed obtained when 

the load factor corrected lift coefficient 

(nzw W/qS) is first a maximum during the 

maneuver prescribed in condition 

(c)(5)(viii) of these Special Conditions; 

nzw = Load factor normal to the flight path 

at VCLmax; 

W = Airplane gross weight; 

S = Aerodynamic reference wing area; and 

q = Dynamic pressure. 

(5) VCLmax is determined in non-icing 

conditions with: 

(i) Engines idling, or, if that resultant 

thrust causes an appreciable decrease in 

stall speed, not more than zero thrust at 

the stall speed; 

(ii) The airplane in other respects 

(such as flaps and landing gear) in the 

condition existing in the test or 

performance standard in which VSR is 

being used; 

(iii) The weight used when VSR is 

being used as a factor to determine 

compliance with a required 

performance standard; 

(iv) The center of gravity position that 

results in the highest value of reference 

stall speed; 

(v) The airplane trimmed for straight 

flight at a speed achievable by the 

automatic trim system, but not less than 

1.13 VSR and not greater than 1.3 VSR; 

(vi) Alpha-floor system inhibited; and 

(vii) The high-incidence protection 

system adjusted, at the option of the 

applicant, to allow higher incidence 

than is possible with the normal 

production system. 

(viii) Starting from the stabilized trim 

condition, apply the longitudinal 

control to decelerate the airplane so that 

the speed reduction does not exceed 1 

knot per second. 

(d) Stall Warning 

In lieu of § 25.207, the following 

requirements apply: 

(1) Normal Operation. 

If the capabilities of the highincidence protection system are met, 

then condition (b) of these Special 

Conditions are satisfied. These 

conditions provide an equivalent level 

of safety to § 25.207, Stall Warning, so 

the provision of an additional, unique 

warning device is not required. 

(2) High-Incidence Protection System 

Failure. 

(i) In non-icing conditions, following 

failures of the high-incidence protection 

system, not shown to be extremely 

improbable, such that the capability of 

the system no longer satisfies conditions 

(b)(1), (2), and (3) of these Special 

Conditions, stall warning must be 

provided in accordance with 

§ 25.207(a), (b), and (f). 

(ii) In icing conditions, after a failure 

leading to the loss of the high-incidence 

protection system, a safety margin not 

less than 3 percent or 3 knots between 

stall warning and stall must be 

maintained. 

(e) Handling Characteristics at High 

Incidence 

(1) High Incidence Handling 

Demonstrations. 

In lieu of § 25.201: High-incidence 

handling demonstration in icing and 

non-icing conditions: 

(i) Maneuvers to the limit of the 

longitudinal control, in the nose up 

sense, must be demonstrated in straight 

flight and in 30-degree banked turns 

with: 

(A) The high-incidence protection 

system operating normally. 

(B) Initial power conditions of: 

(1) Power off. 

(2) The power necessary to maintain 

level flight at 1.5 VSR1, where VSR1 is the 

reference stall speed with flaps in 

approach position, the landing gear 

retracted, and maximum landing 

weight. 

(C) Alpha-floor system operating 

normally unless more severe conditions 

are achieved with inhibited alpha floor. 

(D) Flaps, landing gear, and 

deceleration devices in any likely 

combination of positions. 

(E) Representative weights within the 

range for which certification is 

requested; and 

(F) The airplane trimmed for straight 

flight at a speed achievable by the 

automatic trim system. 

(ii) The following procedures must be 

used to show compliance in non-icing 

and icing conditions: 

(A) Starting at a speed sufficiently 

above the minimum steady flight speed 

to ensure that a steady rate of speed 

reduction can be established, apply the 

longitudinal control so that the speed 

reduction does not exceed 1 knot per 

second until the control reaches the 

stop. 

(B) The longitudinal control must be 

maintained at the stop until the airplane 

has reached a stabilized flight condition, 

and must then be recovered through 

normal recovery techniques. 

(C) Maneuvers with increased 

deceleration rates: 

(1) In non-icing conditions, the 

requirements must also be met with 

increased rates of entry to the incidence 

limit, up to the maximum rate 

achievable. 


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(2) In icing conditions, with the antiice system working normally, the 

requirements must also be met with 

increased rates of entry to the incidence 

limit up to 2 knots per second. 

(D) Maneuvers with ice accretion 

prior to operation of the normal anti-ice 

system: With the ice accretion prior to 

operation of the normal anti-ice system, 

the requirement must also be met in 

deceleration at 1 knot per second up to 

full back stick maintained for at least 3 

seconds before normal recovery is 

performed (requirement to be met with 

and without alpha floor operating). 

(2) Characteristics in High-Incidence 

Maneuvers. 

In lieu of § 25.203: Characteristics in 

High Incidence. 

In icing and non-icing conditions: 

(i) Throughout maneuvers with a rate 

of deceleration of not more than 1 knot 

per second, both in straight flight and in 

30-degree banked turns, the airplane’s 

characteristics must be as follows: 

(A) The airplane must not exhibit 

abnormal nose-up pitching. 

(B) The airplane must not exhibit 

uncommanded nose-down pitching, 

which would be indicative of stall. 

However, reasonable attitude changes 

associated with stabilizing the incidence 

at alpha limit, as the longitudinal 

control reaches the stop, would be 

acceptable. 

(C) The airplane must not exhibit 

uncommanded lateral or directional 

motion, and the pilot must retain good 

lateral and directional control through 

conventional use of the controls, 

throughout the maneuver. 

(D) Buffeting: 

(1) In non-icing conditions, the 

airplane must not exhibit buffeting of a 

magnitude and severity that would act 

as a deterrent from completing the 

maneuver specified in condition (e)(1)(i) 

of these Special Conditions. 

(2) In icing conditions, the airplane 

may exhibit buffeting of a stronger 

magnitude and severity than in nonicing conditions, provided that the 

airplane is demonstrated to be free from 

excessive vibration and buffeting over 

the range of speeds adequate for normal 

operation. 

(ii) In maneuvers with increased rates 

of deceleration, some degradation of 

characteristics are acceptable, associated 

with a transient excursion beyond the 

stabilized alpha limit. However, the 

airplane must not exhibit dangerous 

characteristics, nor characteristics that 

would deter the pilot from holding the 

longitudinal control on the stop for a 

period of time appropriate to the 

maneuver. 

(iii) The pilot must always be able to 

reduce incidence through conventional 

use of the controls. 

(iv) The rate at which the airplane can 

be maneuvered from trim speeds 

associated with scheduled operating 

speeds such as V2 and Vref, up to alpha 

limit, must not be unduly damped or be 

significantly slower than can be 

achieved on conventionally controlled 

transport airplanes. 

(3) Characteristics up to VCLmax. 

Maneuvers with a rate of deceleration 

of not more than 1 knot per second, up 

to the angle of attack at which VCLmax

was obtained as defined in condition 

(c)(4) of these Special Conditions, must 

be demonstrated in straight flight and in 

30-degree banked turns with: 

(i) The high-incidence protection 

system deactivated or adjusted, at the 

option of the applicant, to allow higher 

incidence than is possible with the 

normal production system, 

(ii) Alpha-floor system inhibited, 

(iii) Engines idling, 

(iv) Flaps and landing gear in any 

likely combination of positions, and 

(v) The airplane trimmed for straight 

flight at a speed achievable by the 

automatic trim system. 

During such maneuvers, the airplane 

must not exhibit dangerous 

characteristics; the pilot must always be 

able to reduce angle of attack by 

conventional use of the controls. The 

pilot must retain good lateral and 

directional control, by conventional use 

of the controls, throughout the 

maneuver. 

(f) Atmospheric Disturbances 

Operation of the high-incidence 

protection system must not adversely 

affect airplane control during expected 

levels of atmospheric disturbances, nor 

impede the application of recovery 

procedures in case of wind shear. This 

must be demonstrated in non-icing 

conditions only, and must allow for 

drawing conclusion for icing conditions 

without further demonstration. 

(g) Speed Associated With Other 

Requirements 

The design must meet the following 

modified requirements: 

a. Section 25.145(a): Vmin in lieu of 

‘‘stall identification.’’ 

b. Section 25.145(b): Vmin in lieu of 

Vsw. 

c. Section 25.1323(d): ‘‘From 1.23 VSR

to Vmin’’ in lieu of ‘‘1.23 VSR to stall 

warning speed’’ and ‘‘speeds below 

Vmin’’ in lieu of ‘‘speeds below stall 

warning.’’ 

(h) Alpha Floor 

In icing and non-icing conditions, the 

alpha-floor setting must be such that the 

airplane can be flown at the speeds and 

bank angles specified in § 25.143(h). 

The applicant also must show that the 

alpha-floor setting does not interfere 

with normal maneuvering of the 

airplane. In addition, the airplane must 

exhibit no alpha-floor triggering unless 

appropriate when the airplane is flown 

in usual operational maneuvers and in 

turbulence. 

(i) Proof of Compliance 

In addition to the requirements in 

§ 25.21(b), the following requirement 

applies: 

The flying qualities will be evaluated 

at the most unfavorable center-of-gravity 

(CG) position. 

(j) Performance in Icing Conditions 

(1) Take-off 

In lieu of compliance with 

§ 25.105(a)(2)(i), the following special 

conditions apply: 

(a) In icing conditions, if in the 

configuration used in showing 

compliance with § 25.121(b), and with 

the most critical of the ‘‘Take-off Ice’’ 

accretion(s) defined in 14 CFR part 25, 

amendment 121, appendix C: 

(i) The V2 speed scheduled in nonicing conditions does not provide the 

maneuvering capability specified in 

§ 25.143(h) for the take-off 

configuration. 

Note: This requirement does not apply if 

the Vmin1g is increased in icing conditions, 

with the ‘‘Take-off Ice’’ accretion defined in 

part 25, amendment 121, appendix C, by less 

than 2.5 knots or 2.5 percent, whichever is 

greater. 

(2) Climb: one-engine inoperative. 

In lieu of compliance with 

§ 25.121(b)(2)(ii)(A), the following 

special conditions apply: 

(a) In icing conditions, with the most 

critical of the take-off ice accretion(s) 

defined in appendix C, if in the 

configuration used to show compliance 

with § 25.121(b) with this take-off ice 

accretion: 

(i) The V2 speed scheduled in nonicing conditions does not provide the 

maneuvering capability specified in 

§ 25.143(h), for the take-off 

configuration. 

Note: This requirement does not apply if 

the Vmin1g is increased in icing conditions, 

with the ‘‘Take-off Ice’’ accretion defined in 

14 CFR part 25, amendment 121, appendix C, 

by less than 2.5 knots or 2.5 percent, 

whichever is greater. 

In lieu of compliance with 

§ 25.121(c)(2)(ii)(A) and (B), the 

following special conditions apply: 

(a) In icing conditions, with the most 

critical of the final take-off ice 

accretion(s) defined in appendix C, if in 


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the configuration used to show 

compliance with § 25.121(b) with the 

take-off ice accretion used to show 

compliance with § 25.111(c)(5)(i): 

(i) The VFTO (final take-off speed) 

scheduled in non-icing conditions does 

not provide the maneuvering capability, 

specified in § 25.143(h), for the en-route 

configuration. 

Note: This requirement does not apply if 

the Vmin1g is increased in icing conditions, 

with the ‘‘Final Take-off Ice’’ accretion 

defined in 14 CFR part 25, amendment 121, 

appendix C, by less than 2.5 knots or 2.5 

percent, whichever is greater. 

(ii) The degradation of the gradient of 

climb, determined in accordance with 

§ 25.121(b), with the take-off ice 

accretion used in showing compliance 

with § 25.111(c)(5)(i), is greater than 

one-half of the applicable actual-to-net 

take-off flight path gradient reduction 

defined in § 25.115(b); 

In lieu of compliance with 

25.121(d)(2)(ii), the following special 

conditions apply: 

(a) In icing conditions, with the most 

critical of the approach ice accretion(s) 

defined in 14 CFR part 25, amendment 

121, appendix C, as applicable, in a 

configuration corresponding to the 

normal all-engines-operating procedure, 

the Vmin1g for this configuration does 

not exceed 110 percent of the Vmin1g for 

the related all-engines-operating landing 

configuration in icing conditions, with a 

climb speed established with normal 

landing procedures, but not more than 

1.4 VSR (VSR determined in non-icing 

conditions). 

(3) En-route flight paths. 

In lieu of compliance with 

25.123(b)(2)(i), the following special 

conditions apply: 

(a) In icing conditions with the most 

critical of the en-route ice accretion(s) 

defined in 14 CFR part 25, amendment 

121, appendix C, if: 

(i) The VFTO speed scheduled in nonicing conditions does not provide the 

maneuvering capability, specified in 

§ 25.143(h), for the en-route 

configuration. 

Issued in in Kansas City, Missouri, on 

October 27, 2023. 

Patrick R. Mullen, 

Manager, Technical Policy Branch, Policy and 

Standards Division, Aircraft Certification 

Service. 

[FR Doc. 2023–24311 Filed 11–2–23; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2021–1034; Notice No. 25– 

23–02–SC] 

Special Conditions: Airbus Model 

A321neo XLR Airplane; Electronic 

Flight-Control System: LateralDirectional and Longitudinal Stability, 

and Low-Energy Awareness. 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed special 

conditions. 

SUMMARY: This action proposes special 

conditions for the Airbus Model 

A321neo XLR airplane. The airplane 

will have a novel or unusual design 

feature when compared to the state of 

technology envisioned in the 

airworthiness standards for transportcategory airplanes. This design feature 

is an electronic flight-control system 

(EFCS) associated with lateraldirectional and longitudinal stability, 

and low-energy awareness. 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: Send comments on or before 

December 4, 2023. 

ADDRESSES: Send comments identified 

by Docket No. FAA–2021–1034 using 

any of the following methods: 

Federal eRegulations Portal: Go to 

https://www.regulations.gov/ and follow 

the online instructions for sending your 

comments electronically. 

Mail: Send comments to Docket 

Operations, M–30, U.S. Department of 

Transportation (DOT), 1200 New Jersey 

Avenue SE, Room W12–140, West 

Building Ground Floor, Washington, DC 

20590–0001. 

Hand Delivery or Courier: Take 

comments to Docket Operations in 

Room W12–140 of the West Building 

Ground Floor at 1200 New Jersey 

Avenue SE, Washington, DC, between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. 

Fax: Fax comments to Docket 

Operations at 202–493–2251. 

Docket: Background documents or 

comments received may be read at 

https://www.regulations.gov/ at any 

time. Follow the online instructions for 

accessing the docket or go to Docket 

Operations in Room W12–140 of the 

West Building Ground Floor at 1200 

New Jersey Avenue SE, Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

FOR FURTHER INFORMATION CONTACT: Troy 

Brown, Performance and Environment 

Unit, AIR–621A, Technical Policy 

Branch, Policy and Standards Division, 

Aircraft Certification Service, Federal 

Aviation Administration, 1801 S Airport 

Rd., Wichita, KS 67209–2190; telephone 

and fax 405–666–1050; email 

troy.a.brown@faa.gov. 

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. 

Certification of the Airbus Model 

A321neo XLR airplane is currently 

scheduled for December 2023. The 

substance of these special conditions, in 

all material respects, has been subject to 

the notice and public-comment 

procedure in several prior instances. 

Therefore, because a delay would 

significantly affect the applicant’s 

installation of the new or unusual 

feature, and delay certification of the 

airplane, the FAA is reducing the 

public-comment period to 30 days. 

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 https://

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 


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