Document ID: FAA-2017-0482-0001
Agency: faa
Document Type: Rule
Title: Special Conditions: Airbus Model A330-841 and A330-941 New Engine Option (A330neo) Airplanes; Use of High-Incidence Protection and Alpha-Floor Systems
Posted Date: 2018-01-16T05:00Z

[Federal Register Volume 83, Number 10 (Tuesday, January 16, 2018)]
[Rules and Regulations]
[Pages 2035-2038]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-00546]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2017-0482; Special Conditions No. 25-709-SC]

Special Conditions: Airbus Model A330-841 and A330-941 New Engine 
Option (A330neo) Airplanes; Use of High-Incidence Protection and Alpha-
Floor Systems

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Airbus Model A330-
841 and A330-941 New Engine Option (A330neo) 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 a high-incidence protection 
system that limits the angle of attack (AOA) at which the airplane can 
be flown during normal low-speed operations, and that the flightcrew 
cannot override. 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 Airbus on January 16, 2018. Send 
your comments by March 2, 2018.

ADDRESSES: Send comments identified by docket number FAA-2017-0482 
using any of the following methods:
     Federal eRegulations Portal: Go to http://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.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov/, including any personal 
information the commenter provides. Using the search function of the 
docket website, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478).
    Docket: Background documents or comments received may be read at 
http://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: Joe Jacobsen, FAA, Airplane and Flight 
Crew Interface Section, AIR-671, Transport Standards Branch, Policy and 
Innovation Division, Aircraft Certification Service, 1601 Lind Avenue 
SW, Renton, Washington 98057-3356; telephone 425-227-2011; facsimile 
425-227-1320.

[[Page 2036]]

SUPPLEMENTARY INFORMATION: These special conditions are derived from 
special conditions of the same topic for the Airbus Model A380 airplane 
(Special Conditions No. 25-316-SC). The substance of these special 
conditions has been published in the Federal Register for public 
comment in several prior instances. The FAA therefore finds it 
unnecessary to delay the effective date, and finds that good cause 
exists for making these special conditions effective upon publication 
in the Federal Register.

Comments Invited

    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 January 20, 2015, Airbus applied for an amendment to Type 
Certificate no. A46NM to include the new Model A330-841 and A330-941 
New Engine Option airplanes, collectively marketed as Model A330neo 
airplanes. These airplanes, which are derivatives of the Model A330-200 
and A330-300 airplanes currently approved under Type Certificate No. 
A46NM, are wide-body, jet-engine airplanes with a maximum takeoff 
weight of 533,519 pounds, and a passenger capacity of 257 (A330-841); 
or a maximum takeoff weight of 535,503 pounds, and a passenger capacity 
of 287 (A330-941).

Type Certification Basis

    Under the provisions of Sec.  21.101, Airbus must show that the 
Model A330neo airplanes meet the applicable provisions of the 
regulations listed in Type Certificate No. A46NM, or the applicable 
regulations in effect on the date of application for the change except 
for earlier amendments as agreed upon by the FAA.
    For the high-incidence protection system, Airbus will not meet the 
latest standards, as outlined in the Airbus Model A350 airplane special 
conditions (Special Conditions No. 25-517-SC). However, in accordance 
with Sec.  21.101, Airbus has agreed to meet improved standards 
relative to the original Airbus Model A330 airplane certification basis 
corresponding to Airbus Model A380 airplane standards.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., title 14, Code of Federal Regulations (14 CFR) part 
25) do not contain adequate or appropriate safety standards for Model 
A330neo airplanes because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of Sec.  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 Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model A330neo airplanes 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 Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.101.

Novel or Unusual Design Features

    The Airbus Model A330neo airplanes will incorporate the following 
novel or unusual design features:
    A high-incidence protection system that limits the angle of attack 
at which the airplane can be flown during normal low-speed operations, 
and that the flightcrew cannot override.

Discussion

    The application of this high-incidence protection system, which 
limits the airplane's AOA, impacts the longitudinal airplane handling 
characteristics. In addition, 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.
    The high-incidence protection system prevents the airplane from 
stalling and, therefore, the stall-warning system is not needed during 
normal flight conditions. If there is a failure of this system that is 
not shown to be extremely improbable, the flight characteristics at the 
AOA for lift coefficient CLmax (an airspeed calculated from 
a variety of factors; see item 1.f. in these special conditions) must 
be suitable in the traditional sense, and stall warning must be 
provided in a conventional manner.
    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 
Airbus Model A330-841 and A330-941 (A330neo) airplanes. Should Airbus 
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 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.
    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 Airbus Model A330-841 and A330-941 
(A330neo) airplanes.
    1. Definitions: The following definitions apply for terminology 
that does not appear in 14 CFR part 25:
    a. High-Incidence Protection System: A system that operates 
directly and automatically on the airplane's flying controls to limit 
the maximum incidence that can be attained to a value below that at 
which an aerodynamic stall would occur.
    b. Alpha-Floor System: A system that automatically increases thrust 
on the operating engines when incidence increases through a particular 
value.
    c. Alpha limit: The maximum steady incidence at which the airplane 
stabilizes with the high-incidence protection system operating and the 
longitudinal control held on its aft stop.
    d. Vmin: The minimum steady flight speed, for the 
airplane configuration under consideration and with the high-incidence 
protection system operating, is the final, stabilized, calibrated

[[Page 2037]]

airspeed obtained when the airplane is decelerated at an entry rate not 
exceeding 1 knot per second until the longitudinal pilot controller is 
on its stop.
    e. Vmin1g: Vmin corrected to 1g conditions. 
It 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 AOA not greater than that determined for Vmin.
    f. 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.
    2. Capability and Reliability of the High-Incidence Protection 
System: These special conditions are in lieu of 14 CFR 25.103, 25.145, 
25.201, 25.203, 25.207, and 25.1323, provided that acceptable 
capability and reliability of the high-incidence protection system can 
be established by flight test, simulation, and analysis as appropriate. 
The capability and reliability required are as follows:
    a. It must not be possible during pilot-induced maneuvers to 
encounter a stall, and handling characteristics must be acceptable, as 
required by condition 5 of these special conditions.
    b. The airplane must be protected against stalling due to the 
effects of wind shears and gusts at low speeds, as required by 
condition 6 of these special conditions.
    c. The ability of the high-incidence protection system to 
accommodate any reduction in stalling incidence resulting from residual 
ice must be verified.
    d. The reliability of the system and the effects of failures must 
be acceptable in accordance with Sec.  25.1309 and the associated 
policy.
    3. Minimum Steady Flight Speed and Reference Stall Speed: In lieu 
of Sec.  25.103, the following requirements apply:
    a. Vmin: The minimum steady flight speed, for the 
airplane configuration under consideration and with the high-incidence 
protection system operating, is the final, stabilized, calibrated 
airspeed obtained when the airplane is decelerated at an entry rate not 
exceeding 1 knot per second until the longitudinal control is on its 
stop.
    b. The minimum steady flight speed, Vmin, must be 
determined with:
    i. The high-incidence protection system operating normally.
    ii. Idle thrust.
    iii. Alpha-Floor System inhibited.
    iv. All combinations of flap settings and landing gear positions.
    v. The weight used when VSR is being used as a factor to 
determine compliance with a required performance standard.
    vi. The most unfavorable center of gravity (CG) allowable, and
    vii. The airplane trimmed for straight flight at a speed achievable 
by the automatic trim system.
    c. Vmin1g: Vmin corrected to 1g conditions. 
It is the minimum calibrated airspeed at which the airplane can develop 
a lift force normal to the flight path and equal to the weight of the 
airplane when at an AOA not greater than that determined for 
Vmin. Vmin1g is defined as follows:
[GRAPHIC] [TIFF OMITTED] TR16JA18.000

Where

nzw = load factor normal to the flight path at 
Vmin

    d. The Reference Stall Speed, VSR, is a calibrated 
airspeed defined by the applicant. VSR may not be less than 
a 1g stall speed. VSR is expressed as:
[GRAPHIC] [TIFF OMITTED] TR16JA18.001

Where

VCLmax = Calibrated airspeed obtained when the load-
factor-corrected lift coefficient
[GRAPHIC] [TIFF OMITTED] TR16JA18.002

is first a maximum during the maneuver prescribed in condition 
(3)(e)(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.

    Note: Unless AOA protection-system (stall warning and stall 
identification) production tolerances are acceptably small, so as to 
produce insignificant changes in performance determinations, the 
flight-test settings for stall warning and stall identification 
should be set at the low AOA tolerance limit; high AOA tolerance 
limits should be used for characteristics evaluations.

    e. VCLmax must be determined with the following 
conditions:
    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 CG 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. The Alpha-Floor System inhibited.
    vii. The high-incidence protection system adjusted to a high enough 
incidence to allow full development of the 1g stall.
    viii. Starting from the stabilized trim condition, apply the 
longitudinal control to decelerate the airplane so that the speed 
reduction does not exceed one knot per second.
    f. The flight characteristics at the AOA for CLmax must 
be suitable in the traditional sense at forward (FWD) and aft (AFT) CG 
in straight and turning flight at IDLE power. Although for a normal 
production Electronic Flight Control System (EFCS) and steady full aft 
stick, this AOA for CLmax cannot be achieved. The AOA can be 
obtained momentarily under dynamic circumstances, and deliberately in a 
steady-state sense, with some EFCS failure conditions.
    4. Stall Warning:
    In lieu of Sec.  25.207, the following requirements apply:
    a. Normal Operation: If the items in condition 2, above, are 
satisfied, equivalent safety to the intent of Sec.  25.207, Stall 
Warning, must be considered to have been met without provision of an 
additional, unique warning device.
    b. Failure Cases: Following failures of the high-incidence 
protection system not shown to be extremely improbable, if the system 
no longer satisfies items in conditions 2. a., b., and c., stall 
warning must be provided in accordance with Sec.  25.207. The stall 
warning should prevent inadvertent stall in the following conditions:
    i. Power off straight stall approaches to a speed 5 percent below 
the warning onset.
    ii. Turning-flight stall approaches at entry rates up to 3 knots 
per second when recovery is initiated not less than 1 second after the 
warning onset.
    5. Handling Characteristics at High Incidence:
    a. High-Incidence Handling Demonstrations: In lieu of Sec.  25.201, 
the following requirements apply:
    i. Maneuvers to the limit of the longitudinal control, in the nose-
up direction, must be demonstrated in

[[Page 2038]]

straight flight and in 30-degree banked turns with:
    1. The high-incidence protection system operating normally.
    2. Initial power condition of:
    a. Power off
    b. The power necessary to maintain level flight at 1.5 
VSR1, where VSR1 is the reference stall speed 
with the flaps in the approach position, the landing gear retracted, 
and the maximum landing weight. The flap position to be used in 
determining this power setting is that position in which the stall 
speed, VSR1, does not exceed 110 percent of the stall speed, 
VSR0, with the flaps in the most extended landing position.
    3. Alpha-Floor System operating normally, unless more severe 
conditions are achieved with Alpha floor inhibited.
    4. Flaps, landing gear, and deceleration devices in any likely 
combination of positions.
    5. Representative weights within the range for which certification 
is requested, and
    6. The airplane trimmed for straight flight at a speed achievable 
by the automatic trim system.
    b. The following procedures must be used to show compliance with 
these special conditions:
    i. 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.
    ii. The longitudinal control must be maintained at its stop until 
the airplane has reached a stabilized flight condition, and must then 
be recovered by normal recovery techniques.
    iii. The requirements for turning-flight maneuver demonstrations 
must also be met with accelerated rates of entry to the incidence 
limit, up to the maximum rate achievable.
    c. Characteristics in High Incidence Maneuvers: In lieu of Sec.  
25.203, the following requirements apply:
    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:
    1. There must not be any abnormal airplane nose-up pitching.
    2. There must not be any 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 its stop, would be acceptable. Any 
reduction of pitch attitude associated with stabilizing the incidence 
at the Alpha limit should be achieved smoothly and at a low pitch rate, 
such that it is not likely to be mistaken for natural-stall 
identification.
    3. There must not be any uncommanded lateral or directional motion, 
and the pilot must retain good lateral and directional control by 
conventional use of the cockpit controllers throughout the maneuver.
    4. The airplane must not exhibit buffeting of a magnitude and 
severity that would act as a deterrent to completing the maneuver 
specified in Sec.  25.201(a), as amended by this special condition.
    ii. In maneuvers with increased rates of deceleration, some 
degradation of characteristics, associated with a transient excursion 
beyond the stabilized Alpha limit, is acceptable. However, the airplane 
must not exhibit dangerous characteristics or characteristics that 
would deter the pilot from holding the longitudinal controller on its 
stop for a period of time appropriate to the maneuvers.
    iii. It must always be possible to reduce incidence by conventional 
use of the controller.
    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 
significantly slower than can be achieved on conventionally controlled 
transport airplanes.
    6. 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 and icing conditions.
    7. Alpha Floor: The Alpha-floor setting must be such that the 
airplane can be flown at normal landing operational speed, and 
maneuvered up to bank angles consistent with the flight phase 
(including the maneuver capabilities specified in Sec.  25.143(g)), 
without triggering Alpha floor. In addition, there must be no Alpha-
floor triggering unless appropriate when the airplane is flown in usual 
operational maneuvers and in turbulence.
    8. Proof of Compliance: Change Sec.  25.21 as follows:
    Section 25.21(b)--The flying qualities must be evaluated at the 
most unfavorable CG position.
    9. For Sec. Sec.  25.145(a), 25.145(a), and 25.145(b)(6), the 
following requirements apply:
    a. Section 25.145(a)--It must be possible, at any point between the 
trim speed prescribed in Sec.  25.103(b)(7) as amended by this special 
condition and Vmin, to pitch the nose downward so that the 
acceleration to this selected trim speed is prompt with--
    b. Section 25.145(a)(1)--The airplane trimmed at the trim speed 
prescribed in Sec.  25.103(b)(7) as amended by this special condition.
    c. Section 25.145(b)(6)--With power off, flaps extended and the 
airplane trimmed at 1.3 VSR1, obtain and maintain airspeeds 
between Vmin and either 1.6VSR1 or 
VFE, whichever is lower.
    10. In lieu of Sec.  25.1323(d), the following requirement applies:
    (d) From 1.23 VSR to Vmin, the IAS must change 
perceptibly with CAS and in the same sense, and at speeds below 
Vmin speed the IAS must not change in an incorrect sense.

    Issued in Renton, Washington, on January 9, 2018.
Victor Wicklund,
Manager, Transport Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2018-00546 Filed 1-12-18; 8:45 am]
BILLING CODE 4910-13-P