Document ID: FAA-2015-0455-0001
Agency: faa
Document Type: Proposed Rule
Title: Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and BD-500-1A11; Electronic Flight Control System --Lateral-Directional and Longitudinal Stability and Low-Energy Awareness
Posted Date: 2015-03-05T05:00Z

[Federal Register Volume 80, Number 43 (Thursday, March 5, 2015)]
[Proposed Rules]
[Pages 11958-11960]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-05048]

=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-0455; Notice No. 25-15-04-SC]

Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and 
BD-500-1A11; Electronic Flight Control System: Lateral-Directional 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 Bombardier 
Aerospace Models BD-500-1A10 and BD-500-1A11 series 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 fly-by-wire 
electronic flight control system that provides an electronic interface 
between the pilot's flight controls and the flight control surfaces for 
both normal and failure states. The system generates the actual surface 
commands that provide for stability augmentation and control about all 
three airplane axes. The applicable airworthiness regulations do not 
contain adequate or appropriate safety standards for this design 
feature. These proposed special conditions contain the additional 
safety standards that the Administrator considers necessary to 
establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: Send your comments on or before April 20, 2015.

ADDRESSES: Send comments identified by docket number FAA-2015-0455 
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 Web site, 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), as well as at http://DocketsInfo.dot.gov/.
    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 the 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, ANM-111, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98057-
3356; telephone 425-227-2011; facsimile 425-227-1320.

SUPPLEMENTARY INFORMATION:

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.

[[Page 11959]]

    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 December 10, 2009, Bombardier Aerospace applied for a type 
certificate for their new Models BD-500-1A10 and BD-500-1A11 series 
airplanes (hereafter collectively referred to as ``CSeries''). The 
CSeries airplanes are swept-wing monoplanes with an aluminum alloy 
fuselage, sized for 5-abreast seating. Passenger capacity is designated 
as 110 for the Model BD-500-1A10 and 125 for the Model BD-500-1A11. 
Maximum takeoff weight is 131,000 pounds for the Model BD-500-1A10 and 
144,000 pounds for the Model BD-500-1A11.
    The CSeries flight control system design incorporates normal load 
factor limiting on a full time basis that will prevent the pilot from 
inadvertently or intentionally exceeding the positive or negative 
airplane limit load factor. The FAA considers this feature to be novel 
and unusual in that the current regulations do not provide standards 
for maneuverability and controllability evaluations for such systems. 
Special conditions are needed to ensure adequate maneuverability and 
controllability when using this design feature.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Bombardier Aerospace must show that the CSeries airplanes 
meet the applicable provisions of 14 CFR part 25 as amended by 
Amendments 25-1 through 25-129.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the CSeries 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, 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 CSeries 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, and the FAA must issue a 
finding of regulatory adequacy under Sec.  611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    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.  21.17(a)(2).

Novel or Unusual Design Features

    The CSeries airplanes will incorporate the following novel or 
unusual design feature: Fly-by-wire electronic flight control system 
that provides an electronic interface between the pilot's flight 
controls and the flight control surfaces for both normal and failure 
states. The system generates the actual surface commands that provide 
for stability augmentation and control about all three airplane axes.

Discussion

    In the absence of positive lateral stability, the curve of lateral 
control surface deflections against sideslip angle should be in a 
conventional sense and reasonably in harmony with rudder deflection 
during steady heading sideslip maneuvers.
    Since conventional relationships between stick forces and control 
surface displacements do not apply to the ``load factor command'' 
flight control system on the CSeries airplanes, longitudinal stability 
characteristics should be evaluated by assessing the airplane handling 
qualities during simulator and flight test maneuvers appropriate to the 
operation of the airplane. This may be accomplished by using the 
Handling Qualities Rating Method presented in appendix 5 of Advisory 
Circular (AC) 25-7C, Flight Test Guide for Certification of Transport 
Category Airplanes, dated October 16, 2012, or an acceptable 
alternative method proposed by Bombardier Aerospace. Important 
considerations are as follows:
    (a) Adequate speed control without creating excessive pilot 
workload;
    (b) Acceptable high and low speed protection; and
    (c) Provision of adequate cues to the pilot of significant speed 
excursions beyond VMO/MMO and low speed awareness 
flight conditions.
    The airplane should provide adequate awareness cues to the pilot of 
a low energy (i.e., a low speed, low thrust, or low height) state to 
ensure that the airplane retains sufficient energy to recover when 
flight control laws provide neutral longitudinal stability 
significantly below the normal operating speeds. This may be 
accomplished as follows:
    (a) Adequate low speed/low thrust cues at low altitude may be 
provided by a strong positive static stability force gradient (1 pound 
per 6 knots applied through the sidestick); or
    (b) The low energy awareness may be provided by an appropriate 
warning with the following characteristics:
    i. It should be unique, unambiguous, and unmistakable.
    ii. It should be active at appropriate altitudes and in appropriate 
configurations (i.e., at low altitude, in the approach and landing 
configurations).
    iii. It should be sufficiently timely to allow recovery to a 
stabilized flight condition inside the normal flight envelope while 
maintaining the desired flight path and without entering the flight 
controls angle-of-attack protection mode.
    iv. It should not be triggered during normal operation, including 
operation in moderate turbulence, for recommended maneuvers at 
recommended speeds.
    v. It should not be cancelable by the pilot other than by achieving 
a higher energy state.
    vi. There should be an adequate hierarchy among the warnings so 
that the pilot is not confused and led to take inappropriate recovery 
action if multiple warnings occur.
    Global energy awareness and non-nuisance of low energy cues should 
be evaluated by simulator and flight tests in the whole take-off and 
landing altitude range for which certification is requested. This would 
include all relevant combinations of weight, center-of-gravity 
position, configuration, airbrakes position, and available thrust, 
including reduced and de-rated take-off thrust operations and engine 
failure cases. A sufficient number of tests should be conducted, 
allowing the level of energy awareness and the effects of energy 
management errors to be assessed.
    These proposed special conditions contain the additional safety 
standards that the Administrator considers necessary to establish a 
level of safety equivalent to that established by the existing 
airworthiness standards.

Applicability

    As discussed above, these special conditions are applicable to the 
Bombardier BD-500-1A10 and BD-500-1A11. Should Bombardier Aerospace 
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.

[[Page 11960]]

Conclusion

    This action affects only certain novel or unusual design features 
on two 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 Proposed Special Conditions

0
Accordingly, the Federal Aviation Administration proposes the following 
special conditions as part of the type certification basis for 
Bombardier Aerospace BD-500-1A10 and BD-500-1A11 series airplanes.
    1. 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:
    (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) The static lateral stability (as shown by the tendency to raise 
the low wing in a sideslip with the aileron controls free), for any 
landing-gear and wing-flap position and symmetric-power condition, may 
not be negative at any airspeed (except that speeds higher than 
VFE need not be considered for wing-flaps-extended 
configurations nor speeds higher than VLE for landing-gear-
extended configurations) in the following airspeed ranges:
    i. From 1.13 VSR1 to VMO/MMO.
    ii. From VMO/MMO to VFC/
MFC, unless the divergence is--
    (1) Gradual;
    (2) Easily recognizable by the pilot; and
    (3) Easily controllable by the pilot.
    (e) In straight, steady sideslips over the range of sideslip angles 
appropriate to the operation of the airplane, but not less than those 
obtained with one half of the available rudder control movement (but 
not exceeding a rudder control force of 180 pounds), rudder control 
movements and forces must be substantially proportional to the angle of 
sideslip in a stable sense; and the factor of proportionality must lie 
between limits found necessary for safe operation. This requirement 
must be met for the configurations and speeds specified in paragraph 
(c) of this section.
    (f) For sideslip angles greater than those prescribed by paragraph 
(e) of this section, up to the angle at which full rudder control is 
used or a rudder control force of 180 pounds is obtained, the rudder 
control forces may not reverse, and increased rudder deflection must be 
needed for increased angles of sideslip. Compliance with this 
requirement must be shown using straight, steady sideslips, unless full 
lateral control input is achieved before reaching either full rudder 
control input or a rudder control force of 180 pounds; a straight, 
steady sideslip need not be maintained after achieving full lateral 
control input. This requirement must be met at all approved landing 
gear and wing-flap positions for the range of operating speeds and 
power conditions appropriate to each landing gear and wing-flap 
position with all engines operating.

    Issued in Renton, Washington, on February 24, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-05048 Filed 3-4-15; 8:45 am]
 BILLING CODE 4910-13-P