Special Conditions: Dassault Aviation Model Falcon 7X Airplane; Side Stick Controllers, Electronic Flight Control System: Lateral-Directional and Longitudinal Stability, Low Energy Awareness, Flight Control Surface Position Awareness, and Flight Characteristics Compliance Via the Handling Qualities Rating Method; Flight Envelope Protection: General Limiting Requirements, High Incidence Protection Function, Normal Load Factor (g) Limiting, and Pitch, Roll, and High Speed Limiting Functions, 18365-18372 [E7-6888]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 72, Number 70 (Thursday, April 12, 2007)]
[Rules and Regulations]
[Pages 18365-18372]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-6888]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM370; Special Conditions No. 25-349-SC]


Special Conditions: Dassault Aviation Model Falcon 7X Airplane; 
Side Stick Controllers, Electronic Flight Control System: Lateral-
Directional and Longitudinal Stability, Low Energy Awareness, Flight 
Control Surface Position Awareness, and Flight Characteristics 
Compliance Via the Handling Qualities Rating Method; Flight Envelope 
Protection: General Limiting Requirements, High Incidence Protection 
Function, Normal Load Factor (g) Limiting, and Pitch, Roll, and High 
Speed Limiting Functions

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Dassault Aviation 
Model Falcon 7X airplane. This airplane will have novel or unusual 
design features when compared to the state of technology envisioned in 
the airworthiness standards for transport category airplanes. These 
design features include side stick controllers, electronic flight 
control systems, and flight envelope protections. These special 
conditions pertain to control and handling qualities of the airplane 
and protection limits within the normal flight envelope. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for these design features. 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.

EFFECTIVE DATE: April 4, 2007.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and Flight 
Crew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; telephone (425) 227-2011; facsimile (425) 227-
1149.

SUPPLEMENTARY INFORMATION: 

Background

    On June 4, 2002, Dassault Aviation, 9 rond Point des Champs 
Elysees, 75008, Paris, France, applied for FAA type certificate for its 
new Model Falcon 7X airplane. The Dassault Model Falcon 7X airplane is 
a 19 passenger transport

[[Page 18366]]

category airplane powered by three aft mounted Pratt & Whitney PW307A 
high bypass ratio turbofan engines. Maximum takeoff weight will be 
63,700 pounds, and maximum certified altitude will be 51,000 feet with 
a range of 5,700 nautical miles. The airplane is operated using a fly-
by-wire (FBW) primary flight control system. This will be the first 
application of a FBW primary flight control system in an airplane 
primarily intended for private/corporate use.
    The Dassault Aviation Model Falcon 7X design incorporates equipment 
that was not envisioned when part 25 was created. This equipment 
includes side stick controllers, and an electronic flight control 
system that provides flight envelope protection. Therefore, special 
conditions are required that provide the level of safety equivalent to 
that established by the regulations.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Dassault Aviation must show 
that the Model Falcon 7X airplane meets the applicable provisions of 14 
CFR part 25, as amended by Amendments 25-1 through 25-108.
    If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the Model Falcon 7X airplane because of novel or unusual design 
features, special conditions are prescribed under the provisions of 
Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Dassault Model Falcon 7X 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 Sec.  11.19, under 
Sec.  11.38, and they become part of the type certification basis under 
Sec.  21.17(a)(2).
    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 features, these special conditions would also apply to 
the other model under Sec.  21.101.

Novel or Unusual Design Features

    The Dassault Falcon 7X airplane will incorporate the following 
novel or unusual design features:
     Side stick controllers;
     Electronic flight control system: lateral-directional and 
longitudinal stability, low energy awareness,
     Electronic flight control system: flight control surface 
position awareness,
     Electronic flight control system: flight characteristics 
compliance via the handling qualities rating method (HQRM);
     Flight envelope protection: general limiting requirements,
     Flight envelope protection: high incidence protection 
function,
     Flight envelope protection: normal load factor (g) 
limiting,
     Flight envelope protection: pitch, roll, and high speed 
limiting functions.

Because of these rapid improvements in airplane technology, the 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. These special 
conditions address equipment which may affect the airplane's structural 
performance, either directly or as a result of failure or malfunction. 
These special conditions are identical or nearly identical to those 
previously required for type certification of other airplane models.

Discussion

    Because of these rapid improvements in airplane technology, the 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. Therefore, in 
addition to the requirements of part 25, subparts C and D, the 
following special conditions apply.

Special Condition No. 1. Side Stick Controllers

    The Falcon 7X will use side stick controllers for pitch and roll 
control. Regulatory requirements for conventional wheel and column 
controllers, such as requirements pertaining to pilot strength and 
controllability, are not directly applicable to side stick controllers. 
Certain ergonomic considerations such as armrest support, freedom of 
arm movement, controller displacement, handgrip size and accommodations 
for a range of pilot sizes are not addressed in the regulations. In 
addition, pilot control authority may be uncertain, because the side 
sticks are not mechanically interconnected as with conventional wheel 
and column controls. Pitch and roll control force and displacement 
sensitivity must be compatible, so that normal inputs on one control 
axis will not cause significant unintentional inputs on the other.
    These special conditions require that the unique features of the 
side stick must be demonstrated through flight and simulator tests to 
have suitable handling and control characteristics.

Special Condition No. 2. Electronic Flight Control System: Lateral-
Directional Stability, Longitudinal Stability, and Low Energy Awareness

    In lieu of compliance with the regulations pertaining to lateral-
directional and longitudinal stability, these special conditions ensure 
that the Model Falcon 7X will have suitable airplane handling qualities 
throughout the normal flight envelope.
    The unique features of the Model Falcon 7X flight control system 
and side stick controllers, when compared with conventional airplanes 
with wheel and column controllers, do not provide conventional 
awareness to the flightcrew of a change in speed or a change in the 
direction of flight. These special conditions require that adequate 
awareness be provided to the pilot of a low energy state (low speed, 
low thrust, and low altitude) below normal operating speeds.
    a. Lateral-Directional Static Stability: The electronic flight 
control system (EFCS) on the Falcon 7X contains fly-by-wire control 
laws that result in neutral lateral-directional static stability. 
Therefore, the conventional requirements of the regulations are not 
met.
    The Model Falcon 7X airplane has a flight control design feature 
within the normal operational envelope in which side stick deflection 
in the roll axis commands roll rate. As a result, the stick force in 
the roll axis will be zero (neutral stability) during the straight, 
steady sideslip flight maneuver of Sec.  25.177(c) and will not be 
``substantially proportional to the angle of sideslip,'' as required by 
the regulation.
    With conventional control system requirements, positive static 
directional stability is defined as the tendency to recover from a skid 
with the rudder free. Positive static lateral stability is defined as 
the tendency to raise the low wing in a sideslip with the aileron 
controls free. These special conditions are intended to accomplish the 
following:
     Provide additional cues of inadvertent sideslips and skids 
through control force changes.
     Ensure that short periods of unattended operation do not 
result in any significant changes in yaw or bank angle.
     Provide predictable roll and yaw response.
     Provide acceptable level of pilot attention (i.e., 
workload) to attain and maintain a coordinated turn.

[[Page 18367]]

    b. Longitudinal Static Stability: The longitudinal flight control 
laws for the Falcon 7X provide neutral static stability within the 
normal operational envelope. Therefore, it is inappropriate to require 
the airplane design to comply with the static longitudinal stability 
requirements of Sec. Sec.  25.171, 25.173, and 25.175.
    Static longitudinal stability on conventional airplanes with 
mechanical links to the pitch control surface means that a pull force 
on the controller will result in a reduction in speed relative to the 
trim speed, and a push force will result in higher than trim speed. 
Longitudinal stability is required by the regulations for the following 
reasons:
     Speed change cues are provided to the pilot through 
increased and decreased forces on the controller.
     Short periods of unattended control of the airplane do not 
result in significant changes in attitude, airspeed, or load factor.
     A predictable pitch response is provided to the pilot.
     An acceptable level of pilot attention (i.e., workload) to 
attain and maintain trim speed and altitude is provided to the pilot.
     Longitudinal stability provides gust stability.
    The pitch control movement of the side stick is a normal load 
factor or ``g'' command which results in an initial movement of the 
elevator surface to attain the commanded load factor. That movement is 
followed by integrated movement of the stabilizer and elevator to 
automatically trim the airplane to a neutral (1g) stick-free stability. 
The flight path commanded by the initial side stick input will remain 
stick-free until the pilot gives another command. This control function 
is applied during ``normal'' control law within the speed range from 
the speed at the angle of attack protection limit to initiation of the 
angle of attack protection limit. Once outside this speed range, the 
control laws introduce the conventional longitudinal static stability 
as described above.
    As a result of neutral static stability, the Falcon 7X does not 
meet the part 25 requirements for static longitudinal stability. It 
would not be appropriate to apply the conventional part 25 requirements 
for static longitudinal stability to the unconventional control systems 
of the Falcon 7X. These special conditions require that the airplane be 
shown to have suitable static longitudinal stability in any condition 
normally encountered in service.
    c. Low Energy Awareness: Static longitudinal stability provides an 
awareness to the flightcrew of a low energy state (low speed and thrust 
at low altitude). Past experience on airplanes fitted with a flight 
control system which provides neutral longitudinal stability shows 
there are insufficient feedback cues to the pilot of excursion below 
normal operational speeds. The maximum angle of attack protection 
system limits the airplane angle of attack and prevents stall during 
normal operating speeds, but this system is not sufficient to prevent 
stall at low speed excursions below normal operational speeds. Until 
intervention, there are no stability cues because the airplane remains 
trimmed. Additionally, feedback from the pitching moment due to thrust 
variation is reduced by the flight control laws. Recovery from a low 
speed excursion may become hazardous when the low speed is associated 
with low altitude and the engines are operating at low thrust or with 
other performance limiting conditions.
    Because Sec.  25.173 requires that the pilot receive speed change 
cues through increased or decreased forces on the controller, it would 
be inappropriate to apply those requirements for feedback cues to the 
Falcon Model 7X systems. These special conditions require that the 
airplane provide adequate awareness of a low energy state to the pilot.

Special Condition No. 3. Electronic Flight Control System: Flight 
Control Surface Position Awareness

    With a response-command type of flight control system and no direct 
mechanical coupling from cockpit controller to control surface, the 
controller does not provide the Falcon 7X pilot with an awareness of 
the actual surface deflection position during flight maneuvers. Some 
unusual flight conditions, arising from atmospheric conditions or 
airplane or engine failures or both, may result in full or nearly full 
surface deflection. Unless the flightcrew is made aware of excessive 
deflection or impending control surface deflection limiting, the pilot 
or auto-flight system may encounter situations where loss of control or 
other unsafe handling or performance characteristics occur.
    These special conditions require that suitable annunciation be 
provided to the flightcrew when a flight condition exists in which 
nearly full control surface deflection occurs. Suitability of such a 
display must take into account that some pilot-demanded maneuvers 
(e.g., rapid roll) are necessarily associated with intended full or 
nearly full control surface deflection. Therefore, simple alerting 
systems which function in both intended or unexpected control-limiting 
situations must be properly balanced between needed crew awareness and 
nuisance warnings.

Special Condition No. 4. Electronic Flight Control System: Flight 
Characteristics Compliance Via the Handling Qualities Rating Method 
(HQRM)

    The Model Falcon 7X airplane will have an electronic flight control 
system (EFCS). This system provides an electronic interface between the 
pilot's flight controls and the flight control surfaces (for both 
normal and failure states). The system also generates the actual 
surface commands that provide for stability augmentation and control 
about all three airplane axes. Because EFCS technology has outpaced 
existing regulations-written essentially for unaugmented airplanes with 
provision for limited ON/OFF augmentation-suitable special conditions 
and a method of compliance are required to aid in the certification of 
flight characteristics.
    These special conditions and the method of compliance presented in 
Appendix 7, FAA Handling Qualities Rating Method, of AC 25-7A, Flight 
Test Guide Certification of Transport Category Airplanes, provide a 
means to evaluate flight characteristics--for example, 
``satisfactory,'' ``adequate,'' or ``controllable''--to determine 
compliance with the regulations. The HQRM in Appendix 7 was developed 
for airplanes with control systems having similar functions and is 
employed to aid in the evaluation of the following:
     All EFCS/airplane failure states not shown to be extremely 
improbable and where the envelope (task) and atmospheric disturbance 
probabilities are each 1.
     All combinations of failures, atmospheric disturbance 
level, and flight envelope not shown to be extremely improbable.
     Any other flight condition or characteristic where 14 CFR 
part 25 proves to be inadequate for proper assessment of unique Falcon 
Model 7X flight characteristics.
    The Handling Qualities Rating Method provides a systematic approach 
to the assessment of handling qualities. It is not intended to dictate 
program size or need for a fixed number of pilots to achieve multiple 
opinions. The airplane design itself and success in defining critical 
failure combinations from the many reviewed in Systems Safety 
Assessments dictate the scope of any HQRM application.
    Handling qualities terms, principles, and relationships familiar to 
the aviation community have been used to

[[Page 18368]]

formulate the HQRM. For example, we have established that the well-
known COOPER-HARPER rating scale and the FAA three-part rating system 
are similar. This approach on the flying qualities of highly augmented/ 
relaxed static stability airplanes in relation to regulatory and flight 
test guide requirements is reported in DOT/FAA/CT-82/130, Flying 
Qualities of Relaxed Static Stability Aircraft, Volumes I and II.

Special Condition No. 5. Flight Envelope Protection: General Limiting 
Requirements

    These special conditions and the following ones-pertaining to 
flight envelope protection-present general limiting requirements for 
all the unique flight envelope protection features of the basic Model 
Falcon 7X Electronic Flight Control System (EFCS) design. Current 
regulations do not address these types of protection features. The 
general limiting requirements are necessary to ensure a smooth 
transition from normal flight to the protection mode and adequate 
maneuver capability. The general limiting requirements also ensure that 
the structural limits of the airplane are not exceeded. Furthermore, 
failure of the protection feature must not create hazardous flight 
conditions. Envelope protection parameters include angle of attack, 
normal load factor, pitch angle, and speed. To accomplish these 
envelope protections, one or more significant changes occur in the EFCS 
control laws as the normal flight envelope limit is approached or 
exceeded.
    Each specific type of envelope protection is addressed individually 
in the special conditions that follow.

Special Condition No. 6. Flight Envelope Protection-High Incidence 
Protection Function

    The Falcon 7X is equipped with a high incidence protection function 
that limits the angle of attack at which the airplane can be flown 
during normal low speed operation and that cannot be overridden by the 
flightcrew. This function prevents the airplane from stalling and 
therefore, the stall warning system is not needed during normal flight 
conditions. If there is a failure of the high incidence protection 
function that is not shown to be extremely improbable, the flight 
characteristics at the angle of attack for CLMAX must be 
suitable in the traditional sense, and stall warning must be provided 
in a conventional manner. These special conditions address these and 
other unique features of this function on the Model Falcon 7X.
    These special conditions define a minimum steady flight speed, 
VMIN, to be demonstrated during flight test, at which the 
airplane can develop lift normal to the flight path and equal to its 
weight at the angle of attack limit of the protection function. It 
further defines procedures for establishing the reference stall speed, 
VSR, to be used for defining reference speeds during takeoff 
and landing.
    In the absence of specific regulations in 14 CFR part 25, these 
special conditions present High Incidence Protection Function 
requirements for the capability and reliability of the function, stall 
warning with a failure condition, handling qualities and 
characteristics at high incidence or angle of attack flight maneuvers, 
and specific applications of the newly defined VMIN in lieu 
of current regulations.

Special Condition No. 7. Flight Envelope Protection: Normal Load Factor 
(G) Limiting

    The Falcon 7X flight control system design incorporates a normal 
load factor limiting function on a full time basis that will prevent 
the pilot from inadvertently or intentionally exceeding the positive or 
negative airplane limit load factor. This limiting feature is active in 
the normal flight control mode and cannot be overridden by the pilot. 
There is no requirement in the regulations for this limiting feature.
    This normal load factor limit is unique in that traditional 
airplanes with conventional flight control systems (mechanical 
linkages) are limited in the pitch axis only by the elevator surface 
area and deflection limit. The elevator control power is normally 
derived for adequate controllability and maneuverability at the most 
critical longitudinal pitching moment. The result is that traditional 
airplanes have a significant portion of the flight envelope in which 
maneuverability in excess of limit structural design values is 
possible.
    Part 25 does not require a demonstration of maneuver control or 
handling qualities beyond the design limit structural loads. 
Nevertheless, some pilots have become accustomed to the availability of 
this excess maneuver capacity in case of extreme emergency, such as 
upset recoveries or collision avoidance.
    Because Dassault has chosen to include this optional design feature 
on the Falcon 7X, for which part 25 does not contain adequate or 
appropriate safety standards, special conditions pertaining to this 
feature are included. These special conditions establish minimum load 
factor requirements to ensure adequate maneuver capability during 
normal flight. Other limiting features of the normal load factor 
limiting function, as discussed above, that affect the upper load 
limits are not addressed in these special conditions. The phrase ``in 
the absence of other limiting factors'' has been added relative to past 
similar special conditions to clarify that while the main focus is on 
the lower load factor limits, there are other limiting factors that 
must be considered in the load limiting function.

Special Condition No. 8. Flight Envelope Protection: Pitch, Roll, and 
High Speed Limiting Functions

    The Model Falcon 7X will incorporate pitch attitude and high speed 
limiting functions via the Electronic Flight Control System (EFCS) 
normal operating mode. In addition, positive spiral stability and 
partial pitch compensation will be introduced in the lateral and pitch 
axes through the control laws for bank angles greater than 35 degrees.
    The purpose of the pitch attitude limiting function, in conjunction 
with the high incidence protection function, is to prevent airplane 
stall during low speed, high angle of attack excursions.
    The high speed limiting protection function prevents the pilot from 
inadvertently or intentionally exceeding the airplane maximum design 
speeds, VD/MD. Part 25 does not address such a 
function that would limit or modify flying qualities in the high speed 
region.
    There are no specific hard limits on the Falcon 7X for bank angle. 
At bank angles up to 35 degrees, side movement of the controller 
commands roll rate depending on the amount of deflection. Bank angle is 
immediately accomplished by the control law function and deflection of 
the control surfaces. With the stick released to its neutral point, the 
airplane will maintain the commanded bank angle (neutral spiral 
stability). Positive spiral stability is introduced at and above 35 
degrees band angle such that a stick force is required to maintain bank 
angle, and releasing the stick will return the airplane to 35 degrees.
    In addition to the requirements of Sec.  25.143, this special 
condition establishes requirements to ensure that pitch and high speed 
limiting functions do not impede normal maneuvering and that pitch and 
roll limiting functions do not restrict or prevent attaining bank 
angles necessary for emergency maneuvering.

Discussion of Comments

    Notice of proposed special conditions No. 25-07-06-SC for the 
Dassault

[[Page 18369]]

Aviation Model Falcon 7X airplanes was published in the Federal 
Register on February 26, 2007 (72 FR 8296). No comments were received, 
and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Dassault Aviation Model Falcon 7X airplanes. Should Dassault Aviation 
apply at a later date for a change to the type certificate to include 
another model on the same type certificate incorporating the same novel 
or unusual design features, these special conditions would apply to 
that model as well.

For Final Special Conditions Effective Upon Issuance

    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register; however, as the certification date for the Dassault 
Aviation Model Falcon 7X airplanes is imminent, the FAA finds that good 
cause exists to make these special conditions effective upon issuance.

Conclusion

    This action affects only certain novel or unusual design features 
on model Falcon 7X 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 Dassault Aviation Model Falcon 7X 
airplanes.

1. Side Stick Controllers

    In the absence of specific requirements for side stick controllers, 
the following special conditions apply:
    a. Pilot strength: In lieu of the ``strength of pilots'' limits 
shown in Sec.  25.143(c) for pitch and roll, and in lieu of the 
specific pitch force requirements of Sec. Sec.  25.145(b) and 
25.175(d), it must be shown that the temporary and maximum prolonged 
force levels for the side stick controllers are suitable for all 
expected operating conditions and configurations, whether normal or 
non-normal.
    b. Pilot control authority: The electronic side stick controller 
coupling design must provide for corrective and/or overriding control 
inputs by either pilot with no unsafe characteristics. Annunciation of 
the controller status must be provided, and must not be confusing to 
the flightcrew.
    c. Pilot control: It must be shown by flight tests that the use of 
side stick controllers does not produce unsuitable pilot-in-the-loop 
control characteristics when considering precision path control/tasks 
and turbulence. In addition, pitch and roll control force and 
displacement sensitivity must be compatible, so that normal inputs on 
one control axis will not cause significant unintentional inputs on the 
other.
    d. Autopilot quick-release control location: In lieu of compliance 
with Sec.  25.1329(d), autopilot quick release (emergency) controls 
must be on both side stick controllers. The quick release means must be 
located so that it can readily and easily be used by the flightcrew.

2. Electronic Flight Control System: Lateral-Directional and 
Longitudinal Stability, and Low Energy Awareness

    In lieu of the requirements of Sec. Sec.  25.171, 25.173, 25.175, 
and 25.177(c), the following special conditions apply:
    a. The airplane must be shown to have suitable static lateral, 
directional, and longitudinal stability in any condition normally 
encountered in service, including the effects of atmospheric 
disturbance. The showing of suitable static lateral, directional and 
longitudinal stability must be based on the airplane handling 
qualities, including pilot workload and pilot compensation, for 
specific test procedures during the flight test evaluations.
    b. The airplane must provide adequate awareness to the pilot of a 
low energy (low speed/low thrust/low height) state when fitted with 
flight control laws presenting neutral longitudinal stability 
significantly below the normal operating speeds. ``Adequate awareness'' 
means warning information must be provided to alert the crew of unsafe 
operating conditions and to enable them to take appropriate corrective 
action.
    c. The static directional stability--as shown by the tendency to 
recover from a skid with the rudder free--must be positive for any 
landing gear and flap position and symmetrical power condition, at 
speeds from 1.13 VSR1 up to VFE, VLE, 
or VFC/MFC (as appropriate).
    d. In straight, steady sideslips (unaccelerated forward slips), the 
rudder control movements and forces must be substantially proportional 
to the angle of sideslip, and the factor of proportionality must be 
between limits found necessary for safe operation throughout the range 
of sideslip angles appropriate to the operation of the airplane. At 
greater angles--up to the angle at which full rudder control is used or 
a rudder pedal force of 180 pounds (81.72 kg) is obtained--the rudder 
pedal forces may not reverse, and increased rudder deflection must 
produce increased angles of sideslip. Unless the airplane has a 
suitable sideslip indication, there must be enough bank and lateral 
control deflection and force accompanying sideslipping to clearly 
indicate any departure from steady, unyawed flight.

3. Electronic Flight Control System: Flight Control Surface Position 
Awareness

    In addition to the requirements of Sec. Sec.  25.143, 25.671 and 
25.672, the following special conditions apply:
    a. A suitable flight control position annunciation must be provided 
to the crew in the following situation:
    A flight condition exists in which--without being commanded by the 
crew--control surfaces are coming so close to their limits that return 
to normal flight and (or) continuation of safe flight requires a 
specific crew action.
    b. In lieu of control position annunciation, existing indications 
to the crew may be used to prompt crew action, if they are found to be 
adequate.

    Note: The term ``suitable'' also indicates an appropriate 
balance between nuisance and necessary operation.

4. Electronic Flight Control System: Flight Characteristics Compliance 
Via the Handling Quantities Rating Method (HQRM)

    a. Flight characteristics compliance determination for electronic 
flight control system (EFCS) Failure Cases:
    In lieu of compliance with Sec.  25.672(c), the HQRM contained in 
Appendix 7, FAA Handling Qualities Rating Method, of the Flight Test 
Guide for Certification of Transport Category Airplanes, AC 25-7A (or 
an equivalent method of compliance found acceptable to the FAA), must 
be used for evaluation of EFCS configurations resulting from single and 
multiple failures not shown to be extremely improbable.
    The handling qualities ratings are:
    (1) Satisfactory: Full performance criteria can be met with routine 
pilot effort and attention.
    (2) Adequate: Adequate for continued safe flight and landing; full 
or specified

[[Page 18370]]

reduced performance can be met, but with heightened pilot effort and 
attention.
    (3) Controllable: Inadequate for continued safe flight and landing, 
but controllable for return to a safe flight condition, safe flight 
envelope and/or reconfiguration, so that the handling qualities are at 
least Adequate.
    b. Handling qualities will be allowed to progressively degrade with 
failure state, atmospheric disturbance level, and flight envelope, as 
shown in Figure 12, ``Minimum HQ Requirements,'' of Appendix 7. 
Specifically, for probable failure conditions within the normal flight 
envelope, the pilot-rated handling qualities must be satisfactory in 
light atmospheric disturbance and adequate in moderate atmospheric 
disturbance. The handling qualities rating must not be less than 
adequate in light atmospheric disturbance for improbable failures.

    Note: AC 25-7A, Appendix 7 presents a method of compliance and 
provides guidance for the following:
     Minimum handling qualities rating requirements in 
conjunction with atmospheric disturbance levels, flight envelopes, 
and failure conditions (Figure 12),
     Flight Envelope definition (Figures 5A, 6 and 7),
     Atmospheric Disturbance Levels (Figure 5B),
     Flight Control System Failure State (Figure 5C),
     Combination Guidelines (Figures 5D, 9 and 10), and
     General flight task list, from which appropriate 
specific tasks can be selected or developed (Figure 11).

5. Flight Envelope Protection: General Limiting Requirements

    a. General Requirements.
    (1) Onset characteristics of each envelope protection function must 
be smooth, appropriate to the phase of flight and type of maneuver, and 
not in conflict with the ability of the pilot to satisfactorily change 
the airplane flight path, speed, or attitude, as needed.
    (2) Limit values of protected flight parameters (and if applicable, 
associated warning thresholds) must be compatible with the following:
    (a) Airplane structural limits,
    (b) Required safe and controllable maneuvering of the airplane, and
    (c) Margins to critical conditions. Dynamic maneuvering, airframe 
and system tolerances (both manufacturing and in-service), and non-
steady atmospheric conditions--in any appropriate combination and phase 
of flight--must not result in a limited flight parameter beyond the 
nominal design limit value that would cause unsafe flight 
characteristics.
    (3) The airplane must be responsive to intentional dynamic 
maneuvering to within a suitable range of the parameter limit. Dynamic 
characteristics, such as damping and overshoot, must also be 
appropriate for the flight maneuver and limit parameter in question.
    (4) When simultaneous envelope limiting is engaged, adverse 
coupling or adverse priority must not result.
    b. Failure States: EFCS failures, including sensor failures, must 
not result in a condition where a parameter is limited to such a 
reduced value that safe and controllable maneuvering is no longer 
available. The crew must be alerted by suitable means, if any change in 
envelope limiting or maneuverability is produced by single or multiple 
failures of the EFCS not shown to be extremely improbable.

6. Flight Envelope Protection: High Incidence Protection Function

    a. Definitions. For the purpose of this special condition, the 
following definitions apply:
    Electronic Flight Control System (EFCS): The electronic and 
software command and control elements of the flight control system.
    High Incidence Protection Function: An airplane level function that 
automatically limits the maximum angle of attack that can be attained 
to a value below that at which an aerodynamic stall would occur.
    Alpha Limit: The maximum angle of attack at which the airplane 
stabilizes with the high incidence protection function operating and 
the longitudinal control held on its aft stop.
    VMIN: The minimum steady flight speed is the stabilized, calibrated 
airspeed obtained when the airplane is decelerated at an entry rate not 
exceeding 1 knot per second, until the longitudinal pilot control is on 
its stop with the high incidence protection function operating.
    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 
angle of attack not greater than that determined for VMIN.
    b. Capability and Reliability of the High Incidence Protection 
Function
    (1) It must not be possible to encounter a stall during pilot 
induced maneuvers, and handling characteristics must be acceptable, as 
required by paragraphs e and f below, titled High Incidence Handling 
Demonstrations and High Incidence Handling Characteristics 
respectively.
    (2) The airplane must be protected against stalling due to the 
effects of environmental conditions such as windshears and gusts at low 
speeds, as required by paragraph g, Atmospheric Disturbances, below.
    (3) The ability of the high incidence protection function to 
accommodate any reduction in stalling incidence resulting from residual 
ice must be verified.
    (4) The reliability of the function and the effects of failures 
must be acceptable, in accordance with Sec.  25.1309 and Advisory 
Circular 25.1309-1A, System Design and Analysis.
    (5) The high incidence protection function must not impede normal 
maneuvering for pitch angles up to the maximum required for normal 
maneuvering, including a normal all-engines operating takeoff plus a 
suitable margin to allow for satisfactory speed control.
    c. Minimum Steady Flight Speed and Reference Stall Speed. In lieu 
of the requirements of Sec.  25.103, the following special conditions 
apply:
    (1) VMIN: The minimum steady flight speed, for the 
airplane configuration under consideration and with the high incidence 
protection function 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 pilot control is on 
its stop.
    (2) The minimum steady flight speed, VMIN, must be 
determined with:
    (a) The high incidence protection function operating normally.
    (b) Idle thrust.
    (c) All combinations of flap settings and landing gear positions.
    (d) The weight used when VSR is being used as a factor 
to determine compliance with a required performance standard.
    (e) The most unfavorable center of gravity allowable, and
    (f) The airplane trimmed for straight flight at a speed achievable 
by the automatic trim system.
    (3) VMIN1g is VMIN corrected to 1g 
conditions. VMIN1g 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. VMIN1g is defined as 
follows:
[GRAPHIC] [TIFF OMITTED] TR12AP07.007

Where--

nzw = load factor normal to the flight path at 
VMIN

    (4) The Reference Stall Speed, VSR, is a calibrated 
airspeed selected by the

[[Page 18371]]

applicant. VSR may not be less than the 1g stall speed. 
VSR is expressed as:
[GRAPHIC] [TIFF OMITTED] TR12AP07.008

Where--

VCLMAX = Calibrated airspeed obtained when the load 
factor-corrected lift coefficient
[GRAPHIC] [TIFF OMITTED] TR12AP07.009

 is first a maximum during the maneuver prescribed in paragraph 
(5)(h) of this special condition.
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 must be determined with the following 
conditions:
    (a) Engines idling or--if that resultant thrust causes an 
appreciable decrease in stall speed--not more than zero thrust at the 
stall speed
    (b) 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.
    (c) The weight used when VSR is being used as a factor 
to determine compliance with a required performance standard.
    (d) The center of gravity position that results in the highest 
value of reference stall speed.
    (e) 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.
    (f) [Reserved]
    (g) The high incidence protection function adjusted to a high 
enough incidence to allow full development of the 1g stall.
    (h) 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.
    (6) The flight characteristics at the angle of attack for 
CLMAX must be suitable in the traditional sense at FWD and 
AFT center of gravity in straight and turning flight at IDLE power. 
Although for a normal production EFCS and steady full aft stick this 
angle of attack for CLMAX cannot be achieved, the angle of 
attack can be obtained momentarily under dynamic circumstances and 
deliberately in a steady state sense with some EFCS failure conditions.
    (7) The reference stall speed, VSR, is a calibrated 
airspeed defined by the applicant. If VSR is chosen equal to 
VMIN1g, an equivalent safety finding to the intent of Sec.  
25.103 may be considered to have been met. The applicant may choose 
VSR to be less than VMIN1g but not less than 
VS1g if compensating factors are provided to ensure safe 
characteristics.
    d. Stall Warning.
    (1) Normal Operation. If the conditions of paragraph b, Capability 
and Reliability of the High Incidence Protection Function, of this 
special conditions are satisfied, a level of safety equivalent to that 
intended by Sec.  25.207, Stall Warning, must be considered to have 
been met without provision of an additional, unique warning device.
    (2) Failure Cases. Following failures of the high incidence 
protection function not shown to be extremely improbable, if the 
function no longer satisfies paragraph b, Capability and Reliability of 
the High Incidence Protection Function, paragraphs b(1), (2), and (3) 
of this special condition, stall warning must be provided in accordance 
with Sec.  25.207. The stall warning should prevent inadvertent stall 
under the following conditions:
    (a) Power off straight stall approaches to a speed 5 percent below 
the warning onset.
    (b) Turning flight stall approaches with at least 1.5g load factor 
normal to the flight path at entry rate of at least 2 knots per second 
when recovery is initiated not less than one second after warning 
onset.
    e. High Incidence Handling Demonstrations. In lieu of the 
requirements of Sec.  25.201, the following special conditions apply:
    Maneuvers to the limit of the longitudinal control in the nose up 
direction must be demonstrated in straight flight and in 30 degree 
banked turns under the following conditions:
    (1) The high incidence protection function 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 to 
determine this power setting is that position in which the stall speed, 
VSR1, does not exceed 110% of the stall speed, 
VSR0, with the flaps in the most extended landing position.
    (3) [Reserved]
    (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.
    f. High Incidence Handling Characteristics. In lieu of the 
requirements of Sec.  25.203, the following special conditions apply:
    (1) In demonstrating the handling characteristics specified in 
paragraphs (2), (3), (4), and (5) below, the following procedures must 
be used:
    (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 one 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 by normal recovery techniques.
    (c) 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.
    (2) 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) There must not be any abnormal airplane nose-up pitching.
    (b) There must not be any uncommanded nose-down pitching that 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. 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.
    (c) 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.
    (d) The airplane must not exhibit buffeting of a magnitude and 
severity that would act as a deterrent to completing the maneuver.
    (3) In maneuvers with increased rates of deceleration, some 
degradation of characteristics is acceptable, associated with a 
transient excursion beyond the stabilized alpha-limit. However, the 
airplane must not exhibit dangerous characteristics or characteristics 
that would deter the pilot from holding the longitudinal controller on 
the stop for a

[[Page 18372]]

period of time appropriate to the maneuvers.
    (4) It must always be possible to reduce incidence by conventional 
use of the controller.
    (5) 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.
    g. Atmospheric Disturbances. Operation of the high incidence 
protection function must not adversely affect aircraft control during 
expected levels of atmospheric disturbances or impede the application 
of recovery procedures in case of windshear. Simulator tests and 
analysis may be used to evaluate such conditions but must be validated 
by limited flight testing to confirm handling qualities at critical 
loading conditions.
    h. [Reserved]
    i. Proof of Compliance. In addition to the requirements of Sec.  
25.21, the following special conditions apply:
    The flying qualities must be evaluated at the most unfavorable 
center of gravity position.
    j. Longitudinal Control:
    (1) In lieu of the requirements of Sec.  25.145(a) and (a)(1), the 
following special conditions apply:
    It must be possible--at any point between the trim speed for 
straight flight and Vmin--to pitch the nose downward, so 
that the acceleration to this selected trim speed is prompt, with:
    The airplane trimmed for straight flight at the speed achievable by 
the automatic trim system and at the most unfavorable center of 
gravity;
    (2) In lieu of the requirements of Sec.  25.145(b)(6), the 
following special conditions apply:
    With power off, flaps extended and the airplane trimmed at 1.3 
VSR1, obtain and maintain airspeeds between Vmin 
and either 1.6 VSR1 or VFE, whichever is lower.
    k. Airspeed Indicating System. (1) In lieu of the requirements of 
Sec.  25.1323(c)(1), the following special conditions apply: 
VMO to Vmin with the flaps retracted.
    (2) In lieu of the requirements of Sec.  25.1323(c)(2), the 
following special conditions apply: Vmin to VFE 
with flaps in the landing position.

7. Flight Envelope Protection: Normal Load Factor (g) Limiting

    In addition to the requirements of Sec.  25.143(a)--and in the 
absence of other limiting factors--the following special conditions 
apply:
    a. The positive limiting load factor must not be less than:
    (1) 2.5g for the Electronic Flight Control System (EFCS) normal 
state.
    (2) 2.0g for the EFCS normal state with the high lift devices 
extended.
    b. The negative limiting load factor must be equal to or more 
negative than:
    (1) Minus 1.0g for the EFCS normal state.
    (2) 0.0g for the EFCS normal state with high lift devices extended.

    Note: This special condition does not impose an upper bound for 
the normal load factor limit, nor does it require that the limit 
exist. If the limit is set at a value beyond the structural design 
limit maneuvering load factor ``n,'' indicated in Sec. Sec.  
25.333(b) and 25.337(b) and (c), there should be a very positive 
tactile feel built into the controller and obvious to the pilot that 
serves as a deterrent to inadvertently exceeding the structural 
limit.

8. Flight Envelope Protection: Pitch, Roll, and High Speed Limiting 
Functions

    In addition to Sec.  25.143, the following special conditions 
apply:
    a. Operation of the high speed limiter during all routine and 
descent procedure flight must not impede normal attainment of speeds up 
to the overspeed warning.
    b. The pitch limiting function must not impede airplane 
maneuvering, including an all-engines operating takeoff, for pitch 
angles up to the maximum required for normal operations plus a suitable 
margin in the pitch axis to allow for satisfactory speed control.
    c. The high speed limiting function must not impede normal 
attainment of speeds up to VMO/MMO during all 
routine and descent procedure flight conditions.
    d. The pitch and roll limiting functions must not restrict nor 
prevent attaining bank angles up to 65 degrees and pitch attitudes 
necessary for emergency maneuvering. Positive spiral stability, which 
is introduced above 35 degrees bank angle, must not require excessive 
pilot strength on the side stick controller to achieve bank angles up 
to 65 degrees. Stick force at bank angles greater than 35 degrees must 
not be so light that over-control would lead to pilot-induced 
oscillations.

    Issued in Renton, Washington, on April 4, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-6888 Filed 4-11-07; 8:45 am]
BILLING CODE 4910-13-P