[Federal Register Volume 79, Number 109 (Friday, June 6, 2014)]
[Rules and Regulations]
[Pages 32637-32639]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-13242]



Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-1040; Notice No. 25-548-SC]

Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and 
BD-500-1A11 Series Airplanes; Flight Envelope Protection: General 
Limiting Requirements

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final Special Conditions.


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 
new control architecture and a full digital flight control system that 
provides flight envelope protections. 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: July 7, 2014.

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.



    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

[[Page 32638]]

Model BD-500-1A10 and 144,000 pounds for the Model BD-500-1A11.
    Bombardier has developed comprehensive flight envelope protection 
features integral to the CSeries electronic flight control system 
(EFCS) design. These flight envelope protection features include 
limitations on angle-of-attack, normal load factor, bank angle, pitch 
angle, and speed. To accomplish this flight envelope limiting, a 
significant change (or multiple changes) occurs in the EFCS control 
laws as the limit is approached or exceeded. When EFCS failure states 
occur, flight envelope protection features can likewise either be 
modified, or in some cases, eliminated. The current regulations were 
not written with these comprehensive flight envelope limiting systems 
in mind.

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 part 25 as amended by Amendments 25-1 
through 25-129 thereto.
    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 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 features: New control architecture and a full digital 
flight control system that provides comprehensive flight envelope 


    The applicable airworthiness regulation is 14 CFR 25.143. The 
purpose of Sec.  25.143 is to verify that any operational maneuvers 
conducted within the operational envelope can be accomplished smoothly 
with average piloting skill and without exceeding any structural 
limits. The pilot should be able to predict the airplane response to 
any control input. During the course of the flight test program, the 
pilot determines compliance with Sec.  25.143 primarily through 
qualitative methods. During flight test, the pilot should evaluate all 
of the following:
     The interface between each protection function;
     Transitions from one mode to another;
     Airplane response to intentional dynamic maneuvering, 
whenever applicable, through dedicated maneuvers;
     General controllability assessment;
     High speed characteristics; and
     High angle-of-attack.
    Section 25.143, however, does not adequately ensure that the novel 
or unusual features of the CSeries airplanes will have a level of 
safety equivalent to that of existing standards. These special 
conditions are therefore required to accommodate the flight envelope 
limiting systems in the CSeries airplanes. The additional safety 
standards in these special conditions will ensure a level of safety 
equivalent to that of existing standards.

Discussion of Comments

    Notice of proposed special conditions No. 25-13-39-SC for the 
Bombardier CSeries airplanes was published in the Federal Register on 
December 11, 2013 (78 FR 75287). No comments were received, and the 
special conditions are adopted as proposed.


    As discussed above, these special conditions are applicable to the 
Models 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.


    This action affects only certain novel or unusual design features 
on two model series of airplanes. It is not a rule of general 

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 

    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 the Bombardier Aerospace Models BD-
500-1A10 and BD-500-1A11 series airplanes.
    1. General Limiting Requirements:
    a. Onset characteristics of each envelope protection feature 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 
airplane flight path, speed, or attitude as needed.
    b. Limit values of protected flight parameters (and, if applicable, 
associated warning thresholds) must be compatible with the following:
    i. Airplane structural limits;
    ii. Required safe and controllable maneuvering of the airplane; and
    iii. Margins to critical conditions. Unsafe flight characteristics/
conditions must not result if dynamic maneuvering, airframe and system 
tolerances (both manufacturing and in-service), and non-steady 
atmospheric conditions, in any appropriate combination and phase of 
flight, can produce a limited flight parameter beyond the nominal 
design limit value.
    c. 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.
    d. When simultaneous envelope limiting is engaged, adverse coupling 
or adverse priority must not result.
    2. Failure States: Electronic flight control system failures 
(including sensor) 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 electronic flight control system not 
shown to be extremely improbable.

[[Page 32639]]

    Issued in Renton, Washington, April 22, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
[FR Doc. 2014-13242 Filed 6-5-14; 8:45 am]