[Federal Register Volume 80, Number 101 (Wednesday, May 27, 2015)]
[Rules and Regulations]
[Pages 30134-30136]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-12699]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2015-0455; Special Conditions No. 25-584-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: Final special conditions.
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SUMMARY: These special conditions are issued 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 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: Effective July 13, 2015.
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 425-227-1320.
SUPPLEMENTARY INFORMATION:
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.
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
[[Page 30135]]
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, Bombardier should
evaluate the longitudinal stability characteristics by assessing the
airplane handling qualities during simulator and flight test maneuvers
appropriate to the operation of the airplane. Bombardier may accomplish
this 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 they may propose an acceptable alternative method. 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) 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
control's 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.
Bombardier should use simulator and flight tests in the whole take-
off and landing altitude range for which certification is requested to
evaluate global energy awareness and non-nuisance of low-energy cues.
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. Bombardier should conduct a sufficient number of
tests to assess the level of energy awareness and the effects of energy
management errors.
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.
Discussion of Comments
Notice of proposed special conditions No. 25-15-04-SC for the
Bombardier CSeries airplanes was published in the Federal Register on
March 5, 2015 (80 FR 11958). No comments were received, and the special
conditions are adopted as proposed.
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.
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 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 Bombardier Aerospace Models 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.
[[Page 30136]]
``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 May 15, 2015.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2015-12699 Filed 5-26-15; 8:45 am]
BILLING CODE 4910-13-P