Document ID: FAA-2013-0820-0001
Agency: faa
Document Type: Rule
Title: Special Conditions: Bombardier Inc., Models BD-500-1A10 and BD-500-1A11 series airplanes; Interactions of Systems and Structures
Posted Date: 2013-10-31T04:00Z

[Federal Register Volume 78, Number 211 (Thursday, October 31, 2013)]
[Rules and Regulations]
[Pages 65156-65161]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-25448]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0820; Notice No. 25-499-SC]

Special Conditions: Bombardier Inc., Models BD-500-1A10 and BD-
500-1A11 Series Airplanes; Interactions of Systems and Structures

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Bombardier Inc. 
Models BD-500-1A10 and BD-500-1A11 series airplanes. These airplanes 
will have novel or unusual features when compared to the state of 
technology envisioned in the airworthiness standards for transport 
category airplanes. These design features include systems that, 
directly or as a result of

[[Page 65157]]

failure or malfunction, affect structural performance. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for these design features. 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: The effective date of these special conditions is October 31, 
2013. We must receive your comments by December 16, 2013.

ADDRESSES: Send comments identified by docket number FAA-2013-0820 
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, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except federal holidays.

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: The FAA has determined that notice of, and 
opportunity for prior public comment on, these special conditions is 
impracticable because these procedures would significantly delay 
issuance of the design approval and thus delivery of the affected 
aircraft. In addition, the substance of these special conditions has 
been subject to the public comment process in several prior instances 
with no substantive comments received. The FAA therefore finds that 
good cause exists for making these special conditions effective upon 
issuance.

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. The Models BD-500-1A10 and BD-500-1A11 series airplanes are 
swept-wing monoplanes with a pressurized cabin, and they share an 
identical supplier base and significant common design elements. The 
fuselage is aluminum alloy material, blended double-bubble design, 
sized for nominal 5-abreast seating. Each airplane's powerplant 
includes two under-wing Pratt and Whitney PW1524G ultra high-bypass, 
geared turbofan engines. Flight controls are fly-by-wire systems with 
two passive/uncoupled side sticks. Avionics include five landscape 
primary cockpit displays. The dimensions 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 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. The range is 3,394 miles 
(5,463 kilometres) for both models of airplanes. The maximum operating 
altitude is 41,000 feet for both models of airplanes.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Bombardier Inc. must show that the Model BD-500-1A10 and 
BD-500-1A11 series airplanes meet the applicable provisions of 14 CFR 
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 Models BD-500-1A10 and BD-500-1A11 
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.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model BD-500-1A10 and BD-500-1A11 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 Models BD-500-1A10 and BD-500-1A11 series airplanes will 
incorporate the following novel or unusual design features: Systems 
that affect the airplane's structural performance, either directly or 
as a result of failure or malfunction. That is, the airplane's systems 
affect how it responds in maneuver and gust conditions, and thereby 
affect its structural capability. These systems may also affect the 
aeroelastic stability of the airplane. Such systems include flight 
control systems, autopilots, stability augmentation systems, load 
alleviation systems, and fuel management systems. These systems 
represent novel and unusual features when compared to the

[[Page 65158]]

technology envisioned in the current airworthiness standards.

Discussion

    The flight control system of the Models BD-500-1A10 and BD-500-1A11 
series airplanes will consist of a full authority fly-by-wire system 
with normal and direct modes of operation. Special conditions have been 
applied on past airplane programs, with similar systems, in order to 
require consideration of the effects of those systems on structures. 
The regulatory authorities and industry developed standardized criteria 
in the Aviation Rulemaking Advisory Committee (ARAC) forum based on the 
criteria defined in Advisory Circular 25.672, dated November 11, 1983. 
The ARAC recommendations have been incorporated in European Aviation 
Safety Agency (EASA) Certification Specifications (CS) 25.302 and CS-25 
Appendix K. FAA rulemaking on this subject is not complete, thus the 
need for special conditions.
    These special conditions are similar to those previously applied to 
other airplane models and to EASA CS 25.302. Transport Canada Civil 
Aviation (TCCA) plans to apply the CS 25.302 version of the special 
conditions. The differences between FAA special conditions and the 
current CS 25.302, which the FAA regards as minor, are shown below.
    (1) Both these special conditions and CS 25.302 specify the design 
load conditions to be considered. Paragraphs 2a(1) and 2b(2)(i) of 
these special conditions clarify that, in some cases, different load 
conditions are to be considered due to other special conditions or 
equivalent level of safety findings.
    (2) Both these special conditions and CS 25.302 allow consideration 
of the probability of being in a dispatched configuration when 
assessing subsequent failures and potential ``continuation of flight'' 
loads (see paragraph 2d below). These special conditions, however, also 
allow using probability when assessing failures that induce loads at 
the ``time of occurrence,'' whereas CS 25.302 does not. The FAA 
provision is relieving. The FAA chooses to preserve these minor 
differences and go forward with this version of the special conditions.

Applicability

    As discussed above, these special conditions are applicable to the 
Models 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 models of airplanes. It is not a rule of general applicability.
    The substance of these special conditions has been subjected to the 
notice and comment period in several prior instances and has been 
derived without substantive change from those previously issued. It is 
unlikely that prior public comment would result in a significant change 
from the substance contained herein. Therefore, because a delay would 
significantly affect the certification of the airplane, which is 
imminent, the FAA has determined that prior public notice and comment 
are unnecessary and impracticable, and good cause exists for adopting 
these special conditions upon publication in the Federal Register. The 
FAA is requesting comments to allow interested persons to submit views 
that may not have been submitted in response to the prior opportunities 
for comment described above.

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 Inc. Models BD-500-1A10 and 
BD-500-1A11 series airplanes.
    1. Interaction of Systems and Structures. General.
    a. For airplanes equipped with systems that affect structural 
performance, either directly or as a result of a failure or 
malfunction, the influence of these systems and their failure 
conditions must be taken into account when showing compliance with the 
requirements of Title 14, Code of Federal Regulations (14 CFR) part 25 
subparts C and D.
    b. The following criteria must be used for showing compliance with 
these special conditions for airplanes equipped with flight control 
systems, autopilots, stability augmentation systems, load alleviation 
systems, flutter control systems, fuel management systems, and other 
systems that either directly or as a result of failure or malfunction 
affect structural performance. If these special conditions are used for 
other systems, it may be necessary to adapt the criteria to the 
specific system.
    c. The criteria defined herein only address the direct structural 
consequences of the system responses and performances and cannot be 
considered in isolation but should be included in the overall safety 
evaluation of the airplane. These criteria may in some instances 
duplicate standards already established for this evaluation. These 
criteria are only applicable to structure whose failure could prevent 
continued safe flight and landing. Specific criteria that define 
acceptable limits on handling characteristics or stability requirements 
when operating in the system degraded or inoperative mode are not 
provided in these special conditions.
    d. Depending upon the specific characteristics of the airplane, 
additional studies may be required that go beyond the criteria provided 
in these special conditions in order to demonstrate the capability of 
the airplanes to meet other realistic conditions such as alternative 
gust or maneuver descriptions for an airplane equipped with a load 
alleviation system.
    e. The following definitions are applicable to these special 
conditions:
    (1) Structural performance: Capability of the airplane to meet the 
structural requirements of 14 CFR part 25.
    (2) Flight limitations: Limitations that can be applied to the 
airplane flight conditions following an in-flight occurrence and that 
are included in the flight manual (e.g., speed limitations and 
avoidance of severe weather conditions).
    (3) Operational limitations: Limitations, including flight 
limitations, that can be applied to the airplane operating conditions 
before dispatch (e.g., fuel, payload and Master Minimum Equipment List 
limitations).
    (4) Probabilistic terms: The probabilistic terms (probable, 
improbable, extremely improbable) used in these special conditions are 
the same as those used in Sec.  25.1309.
    (5) Failure condition: The term ``failure condition'' is the same 
as that used in Sec.  25.1309. However, these special conditions apply 
only to system failure conditions that affect the structural 
performance of the airplane (e.g., system failure conditions that 
induce loads, change the response of the airplane to inputs such as 
gusts or pilot actions, or lower flutter margins).
    2. Effect on Systems and Structures. The following criteria will be 
used in determining the influence of a system

[[Page 65159]]

and its failure conditions on the airplane structure.
    a. System fully operative. With the system fully operative, the 
following apply:
    (1) Limit loads must be derived in all normal operating 
configurations of the system from all the limit conditions specified in 
subpart C (or defined by special conditions or equivalent level of 
safety in lieu of those specified in subpart C), taking into account 
any special behavior of such a system or associated functions or any 
effect on the structural performance of the airplane that may occur up 
to the limit loads. In particular, any significant nonlinearity (rate 
of displacement of control surface, thresholds, or any other system 
nonlinearities) must be accounted for in a realistic or conservative 
way when deriving limit loads from limit conditions.
    (2) The airplane must meet the strength requirements of part 25 
(static strength, residual strength) using the specified factors to 
derive ultimate loads from the limit loads defined above. The effect of 
nonlinearities must be investigated beyond limit conditions to ensure 
the behavior of the system presents no anomaly compared to the behavior 
below limit conditions. However, conditions beyond limit conditions 
need not be considered when it can be shown that the airplane has 
design features that will not allow it to exceed those limit 
conditions.
    (3) The airplane must meet the aeroelastic stability requirements 
of Sec.  25.629.
    b. System in the failure condition. For any system failure 
condition not shown to be extremely improbable, the following apply:
    (1) At the time of occurrence. Starting from 1-g level flight 
conditions, a realistic scenario, including pilot corrective actions, 
must be established to determine the loads occurring at the time of 
failure and immediately after failure.
    (i) For static strength substantiation, these loads, multiplied by 
an appropriate factor of safety that is related to the probability of 
occurrence of the failure, are ultimate loads to be considered for 
design. The factor of safety (FS) is defined in Figure 1.
[GRAPHIC] [TIFF OMITTED] TR31OC13.001

    (ii) For residual strength substantiation, the airplane must be 
able to withstand two thirds of the ultimate loads defined in 
subparagraph 2b(1)(i). For pressurized cabins, these loads must be 
combined with the normal operating differential pressure.
    (iii) Freedom from aeroelastic instability must be shown up to the 
speeds defined in Sec.  25.629(b)(2). For failure conditions that 
result in speeds beyond VC/MC, freedom from 
aeroelastic instability must be shown to increased speeds, so that the 
margins intended by Sec.  25.629(b)(2) are maintained.
    (iv) Failures of the system that result in forced structural 
vibrations (e.g., oscillatory failures) must not produce loads that 
could result in detrimental deformation of primary structure.
    (2) For the continuation of the flight. For the airplane, in the 
system-failed state and considering any appropriate reconfiguration and 
flight limitations, the following apply:
    (i) The loads derived from the following conditions (or defined by 
special conditions or equivalent level of safety in lieu of the 
following conditions) at speeds up to VC/MC, or 
the speed limitation prescribed for the remainder of the flight, must 
be determined:
    (A) The limit symmetrical maneuvering conditions specified in Sec.  
25.331 and in Sec.  25.345.
    (B) The limit gust and turbulence conditions specified in Sec.  
25.341 and in Sec.  25.345.
    (C) The limit rolling conditions specified in Sec.  25.349 and the 
limit unsymmetrical conditions specified in Sec.  25.367 and Sec.  
25.427(b) and (c).
    (D) The limit yaw maneuvering conditions specified in Sec.  25.351.
    (E) The limit ground loading conditions specified in Sec. Sec.  
25.473, 25.491, 25.493(d) and 25.503.
    (ii) For static strength substantiation, each part of the structure 
must be able to withstand the loads in paragraph 2b(2)(i) of these 
special conditions multiplied by a factor of safety depending on the 
probability of being in this failure state. The factor of safety (FS) 
is defined in Figure 2.

[[Page 65160]]

[GRAPHIC] [TIFF OMITTED] TR31OC13.002

    (iii) For residual strength substantiation, the airplane must be 
able to withstand two thirds of the ultimate loads defined in paragraph 
2b(2)(ii) of these special conditions. For pressurized cabins, these 
loads must be combined with the normal operating differential pressure.
    (iv) If the loads induced by the failure condition have a 
significant effect on fatigue or damage tolerance, then their effects 
must be taken into account.
    (v) Freedom from aeroelastic instability must be shown up to a 
speed determined from Figure 3. Flutter clearance speeds V' and V'' may 
be based on the speed limitation specified for the remainder of the 
flight using the margins defined by Sec.  25.629(b).
[GRAPHIC] [TIFF OMITTED] TR31OC13.003

    (vi) Freedom from aeroelastic instability must also be shown up to 
V' in Figure 3 above, for any probable system failure condition 
combined with any damage required or selected for investigation by 
Sec.  25.571(b).
    (3) Consideration of certain failure conditions may be required by 
other sections of 14 CFR part 25 regardless of calculated system 
reliability. Where analysis shows the probability of these failure 
conditions to be less than 10-9, criteria other than those 
specified in this paragraph may be used for structural substantiation 
to show continued safe flight and landing.
    c. Failure indications. For system failure detection and 
indication, the following apply:
    (1) The system must be checked for failure conditions, not 
extremely improbable, that degrade the structural capability below the 
level required by part 25 or significantly reduce the

[[Page 65161]]

reliability of the remaining system. As far as reasonably practicable, 
the flight crew must be made aware of these failures before flight. 
Certain elements of the control system, such as mechanical and 
hydraulic components, may use special periodic inspections, and 
electronic components may use daily checks, in lieu of detection and 
indication systems to achieve the objective of this requirement. These 
certification maintenance requirements must be limited to components 
that are not readily detectable by normal detection and indication 
systems and where service history shows that inspections will provide 
an adequate level of safety.
    (2) The existence of any failure condition, not extremely 
improbable, during flight that could significantly affect the 
structural capability of the airplane and for which the associated 
reduction in airworthiness can be minimized by suitable flight 
limitations, must be signaled to the flight crew. For example, failure 
conditions that result in a factor of safety between the airplane 
strength and the loads of subpart C below 1.25, or flutter margins 
below V'', must be signaled to the crew during flight.
    d. Dispatch with known failure conditions. If the airplane is to be 
dispatched in a known system failure condition that affects structural 
performance, or affects the reliability of the remaining system to 
maintain structural performance, then the provisions of these special 
conditions must be met, including the provisions of paragraph 2a for 
the dispatched condition, and paragraph 2b for subsequent failures. 
Expected operational limitations may be taken into account in 
establishing Pj as the probability of failure occurrence for 
determining the safety margin in Figure 1. Flight limitations and 
expected operational limitations may be taken into account in 
establishing Qj as the combined probability of being in the 
dispatched failure condition and the subsequent failure condition for 
the safety margins in Figures 2 and 3. These limitations must be such 
that the probability of being in this combined failure state and then 
subsequently encountering limit load conditions is extremely 
improbable. No reduction in these safety margins is allowed if the 
subsequent system failure rate is greater than 10-3 per 
hour.

    Issued in Renton, Washington, on September 12, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-25448 Filed 10-30-13; 8:45 am]
BILLING CODE 4910-13-P