
[Federal Register Volume 79, Number 177 (Friday, September 12, 2014)]
[Rules and Regulations]
[Pages 54571-54572]
From the Federal Register Online via the Government Printing 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


