[Federal Register Volume 79, Number 177 (Friday, September 12, 2014)]
[Rules and Regulations]
[Pages 54571-54572]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-21787]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2014-0420; Special Conditions No. 25-565-SC]
Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and
BD-500-1A11 Series Airplanes; Automatic Speed Protection for Design
Dive Speed
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 associated with a
reduced margin between design cruising speed, VC/
MC, and design diving speed, VD/MD,
based on the incorporation of a high-speed protection system that
limits nose down pilot authority at speeds above VD/
MD. 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 Date: October 14, 2014.
FOR FURTHER INFORMATION CONTACT: Mark Freisthler, FAA, Airframe and
Cabin Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-1119; facsimile 425-227-1232.
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.
Bombardier Aerospace proposes to reduce the margin between
VC/MC and VD/MD required by
Title 14, Code of Federal Regulations (14 CFR) 25.335(b) based on the
incorporation of a high-speed protection system in the airplane's
flight control laws. The airplane is equipped with a high-speed
protection system that limits nose down pilot authority at speeds above
VC/MC and prevents the airplane from actually
performing the maneuver required under Sec. 25.335(b)(1).
These special conditions are necessary to address the proposed
high-speed protection system. These special conditions identify various
symmetric and non-symmetric maneuvers that will ensure that an
appropriate design dive speed is established. Symmetric (pitching)
maneuvers are specified in Sec. 25.331, ``Symmetric maneuvering
conditions.'' Non-symmetric maneuvers are specified in Sec. 25.349,
``Rolling conditions,'' and Sec. 25.351, ``Yaw maneuver conditions.''
Type Certification Basis
Under the provisions of 14 CFR 21.17, Bombardier Aerospace must
show that the CSeries airplane meets the applicable provisions of 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 or similar
novel or unusual design feature, the 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 section 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: Bombardier Aerospace proposes to reduce the
margin between VC/MC and VD/
MD required by Sec. 25.335(b) based on the incorporation of
a high-speed protection system in the airplane's flight control laws.
The high-speed protection system limits nose down pilot authority at
speeds above VC/MC and prevents the airplane from
actually performing the maneuver required under Sec. 25.335(b)(1).
Discussion
Section 25.335(b)(1) is an analytical envelope condition that was
originally adopted in Part 4b of the Civil Air Regulations in order to
provide an acceptable speed margin between design cruise speed and
design dive speed. Flutter clearance design speeds and airframe design
loads are impacted by the design dive speed. While the initial
condition for the upset specified in the rule is 1g level flight,
protection is afforded for other inadvertent overspeed conditions as
well. Section 25.335(b)(1) is intended as a conservative enveloping
condition for potential overspeed conditions, including non-symmetric
ones. To establish that potential overspeed conditions are enveloped,
Bombardier Aerospace needs to demonstrate that any reduced speed
margin, based on the high-speed protection system, will not be exceeded
in inadvertent or gust-induced upsets resulting in initiation of the
dive from non-symmetric attitudes; or that the airplane is protected by
the flight control laws from getting into non-symmetric upset
conditions. Bombardier Aerospace needs to conduct a demonstration that
includes a comprehensive set of conditions, as described below.
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. 25-14-06-SC for the
Bombardier Aerospace CSeries airplanes was published in the Federal
Register on July 2, 2014 (79 FR 37674). No comments were received, and
the
[[Page 54572]]
special conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Model BD-500-1A10 and BD-500-1A11 series airplanes. 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, the 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
0
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 (CSeries) airplanes.
Automatic Speed Protection for Design Dive Speed
1. In lieu of compliance with Sec. 25.335(b)(1), if the flight
control system includes functions that act automatically to initiate
recovery before the end of the 20-second period specified in Sec.
25.335(b)(1), VD/MD must be determined from the
greater of the speeds resulting from conditions (a) and (b) below. The
speed increase occurring in these maneuvers may be calculated, if
reliable or conservative aerodynamic data are used.
(a) From an initial condition of stabilized flight at
VC/MC, the airplane is upset so as to take up a
new flight path 7.5 degrees below the initial path. Control
application, up to full authority, is made to try and maintain this new
flight path. Twenty seconds after initiating the upset, manual recovery
is made at a load factor of 1.5g (0.5g acceleration increment), or such
greater load factor that is automatically applied by the system with
the pilot's pitch control neutral. Power, as specified in Sec.
25.175(b)(1)(iv), is assumed until recovery is initiated, at which time
power reduction and the use of pilot-controlled drag devices may be
used.
(b) From a speed below VC/MC, with power to
maintain stabilized level flight at this speed, the airplane is upset
so as to accelerate through VC/MC at a flight
path 15 degrees below the initial path (or at the steepest nose down
attitude that the system will permit with full control authority if
less than 15 degrees). The pilot's controls may be in the neutral
position after reaching VC/MC and before recovery
is initiated. Recovery may be initiated three seconds after operation
of the high-speed warning system by application of a load of 1.5g (0.5g
acceleration increment), or such greater load factor that is
automatically applied by the system with the pilot's pitch control
neutral. Power may be reduced simultaneously. All other means of
decelerating the airplane, the use of which is authorized up to the
highest speed reached in the maneuver, may be used. The interval
between successive pilot actions must not be less than one second.
2. The applicant must also demonstrate that the speed margin,
established as above, will not be exceeded in inadvertent or gust-
induced upsets resulting in initiation of the dive from non-symmetric
attitudes, unless the airplane is protected by the flight control laws
from getting into non-symmetric upset conditions. The upset maneuvers
described in Advisory Circular 25-7C, Flight Test Guide for
Certification of Transport Category Airplanes, section 8, paragraph 32,
sub-paragraphs c(3)(a) and (b) may be used to comply with this
requirement.
3. The probability of any failure of the high-speed protection
system that would result in an airspeed exceeding those determined by
paragraphs 1 and 2 must be less than 10-5 per flight hour.
4. Failures of the system must be annunciated to the pilots. Flight
manual instructions must be provided that reduce the maximum operating
speeds, VMO/MMO. With the system failed, the
operating speed must be reduced to a value that maintains a speed
margin between VMO/MMO and VD/
MD that is consistent with showing compliance with Sec.
25.335(b) without the benefit of the high-speed protection system.
5. Dispatch of the airplane with the high-speed protection system
inoperative could be allowed under an approved minimum equipment list
that would require flight manual instructions to indicate reduced
maximum operating speeds, as described in paragraph (4). In addition,
the flight deck display of the reduced operating speeds, as well as the
overspeed warning for exceeding those speeds, must be equivalent to
that of the normal airplane with the high-speed protection system
operative. Also, it must be shown that no additional hazards are
introduced with the high-speed protection system inoperative.
Issued in Renton, Washington, on September 3, 2014.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2014-21787 Filed 9-11-14; 8:45 am]
BILLING CODE 4910-13-P