Document ID: FAA-2013-1039-0001
Agency: faa
Document Type: Proposed Rule
Title: Special Conditions: Bombardier Inc., Models BD-500-1A10 and BD-500-1A11 series airplanes; Flight Envelope Protection; Normal Load Factor (g) Limiting
Posted Date: 2013-12-11T05:00Z

[Federal Register Volume 78, Number 238 (Wednesday, December 11, 2013)]
[Proposed Rules]
[Pages 75285-75287]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-29486]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-1039; Notice No. 25-13-38-SC]

Special Conditions: Bombardier Inc., Models BD-500-1A10 and BD-
500-1A11 Series Airplanes; Flight Envelope Protection: Normal Load 
Factor (g) Limiting

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Bombardier 
Inc. Models BD-500-1A10 and BD-500-1A11 series airplanes. These 
airplanes will have a novel or unusual design feature associated with 
an electronic flight control system that prevents the pilot from 
inadvertently or intentionally exceeding the positive or negative 
airplane limit load factor. 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 January 27, 2014.

ADDRESSES: Send comments identified by docket number FAA-2013-1039 
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,

[[Page 75286]]

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 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.

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.
    We will consider all comments we receive on or before the closing 
date for comments. We may change these special conditions based on the 
comments we receive.

Background

    On December 10, 2009, Bombardier Inc. applied for a type 
certificate for their new Models BD-500-1A10 and BD-500-1A11 series 
airplanes (hereafter collectively referred to as ``C-series''). The C-
series airplanes are swept-wing monoplanes with a pressurized cabin. 
They share an identical supplier base and significant common design 
elements. The fuselage is aluminum alloy material, blended double-
bubble fuselage, sized for nominal 5-abreast seating. Each airplane's 
powerplant consists of two under wing Pratt and Whitney PW1524G ultra-
high bypass, geared turbofan engines. Flight controls are fly-by-wire 
flight with two passive/uncoupled side sticks. Avionics includes five 
landscape primary cockpit displays. The dimension of the airplanes 
encompass a wingspan of 115 feet; a height of 37.75 feet; and a length 
of 114.75 feet for the Model BD-500-1A10 and a length of 127 feet for 
the Model BD-500-1A11. 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. Maximum takeoff thrust is 21,000 pounds for 
the Model BD-500-1A10 and 23,300 pounds for the Model BD-500-1A11. 
Range is 3,394 miles (5,463 kilometers) for both models of airplanes. 
Maximum operating altitude is 41,000 feet for both model airplanes.
    The design of the electronic flight control system for the C-series 
airplanes incorporates normal load factor limiting on a full time basis 
that prevents the flightcrew from inadvertently or intentionally 
exceeding the positive or negative airplane limit load factor. This 
feature is considered 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 Inc. must show that the C-series 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 C-series 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 C-series 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 C-series airplanes will use a fly-by-wire electronic flight 
control system (EFCS). This system provides an electronic interface 
between the pilot's flight controls and the flight control surfaces for 
both normal and failure states; and it generates the actual surface 
commands that provide for stability augmentation and control about all 
three airplane axes. The design of the EFCS incorporates the following 
novel or unusual design feature: Normal load factor limiting on a full-
time basis that will prevent the flight crew from inadvertently or 
intentionally exceeding the positive or negative airplane limit load 
factor. This feature is considered novel or unusual because the current 
regulations do not provide standards for maneuverability and 
controllability evaluations for such systems. Therefore, special 
conditions are needed to ensure adequate maneuverability and 
controllability when using this design feature.

Discussion

    Title 14 Code of Federal Regulations (14 CFR) part 25 sections do 
not specify requirements or policy for demonstrating maneuver control 
that impose any handling qualities requirements beyond the design limit 
structural loads. Nevertheless, some pilots have become accustomed to 
the availability of this excess maneuver capacity in case of extreme 
emergency such as upset recoveries or collision avoidance.
    As with previous fly-by-wire airplanes, the FAA has no regulatory 
or safety reason to prohibit a design for an electronic flight control 
system with load factor limiting. It is possible that pilots accustomed 
to this feature feel more freedom in commanding full-stick displacement 
maneuvers because of the following:
     Knowledge that the limit system will protect the 
structure,
     Low stick force/displacement gradients,
     Smooth transition from pilot elevator control to limit 
control.
    These special conditions will ensure adequate maneuverability and 
controllability when using this design feature.
    The normal load factor limit on the C-series airplanes is unique in 
that traditional airplanes with conventional flight control systems 
(mechanical linkages) are limited in the pitch axis only by the 
elevator surface area and deflection limit. The elevator control power 
is normally derived for adequate controllability and maneuverability at 
the most critical longitudinal pitching moment. The result is that 
traditional airplanes have a significant portion of the flight envelope 
wherein maneuverability in excess of limit structural design values is 
possible.
    These proposed special conditions for the C-series airplanes 
supplement the applicable regulations, including Sec.  25.143, to 
accommodate the unique features of the flight envelope limiting 
systems, and establish an equivalent level of safety to the existing 
regulations.

Applicability

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

[[Page 75287]]

BD-500-1A10 and BD-500-1A11 series airplanes. Should Bombardier Inc. 
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 Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Bombardier Inc. Models BD-500-1A10 and BD-500-1A11 series 
airplanes.
    1. Flight Envelope Protection: Normal Load Factor (g) Limiting. To 
meet the intent of adequate maneuverability and controllability 
required by Sec.  25.143(a), and in addition to the requirements of 
Sec.  25.143(a) and in the absence of other limiting factors, the 
following special conditions based on Sec.  25.333(b) apply:
    a. The positive limiting load factor must not be less than:
    (1) 2.5g for the normal state of the electronic flight control 
system with the high lift devices retracted.
    (2) 2.0g for the normal state of the electronic flight control 
system with the high lift devices extended.
    b. The negative limiting load factor must be equal to or more 
negative than:
    (1) Minus 1.0g for the normal state of the electronic flight 
control system with the high lift devices retracted.
    (2) 0.0g for the normal state of the electronic flight control 
system with high lift devices extended.
    c. Maximum reachable positive load factor wings level may be 
limited by the characteristics of the electronic flight control system 
or flight envelope protections (other than load factor protection) 
provided that:
    (1) The required values are readily achievable in turns, and
    (2) That wings level pitch up is satisfactory.
    d. Maximum achievable negative load factor may be limited by the 
characteristics of the electronic flight control system or flight 
envelope protections (other than load factor protection) provided that:
    (1) Pitch down responsiveness is satisfactory, and
    (2) From level flight, 0g is readily achievable or alternatively, a 
satisfactory trajectory change is readily achievable at operational 
speeds. For the FAA to consider a trajectory change as satisfactory, 
the applicant should propose and justify a pitch rate that provides 
sufficient maneuvering capability in the most critical scenarios.
    e. Compliance demonstration with the above requirements may be 
performed without ice accretion on the airframe.
    These proposed special conditions do not impose an upper bound for 
the normal load factor limit, nor does it require that the limit exist. 
If the limit is set at a value beyond the structural design limit 
maneuvering load factor ``n'' of Sec. Sec.  25.333(b) and 25.337(b) and 
(c), there should be a very obvious positive tactile feel built into 
the controller so that it serves as a deterrent to inadvertently 
exceeding the structural limit.

    Issued in Renton, Washington, on November 29, 2013.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-29486 Filed 12-10-13; 8:45 am]
BILLING CODE 4910-13-P