83_FR_15370 83 FR 15301 - Special Conditions: Textron Aviation Inc. Model 700 Series Airplanes; Interaction of Systems and Structures

83 FR 15301 - Special Conditions: Textron Aviation Inc. Model 700 Series Airplanes; Interaction of Systems and Structures

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 83, Issue 69 (April 10, 2018)

Page Range15301-15304
FR Document2018-07277

These special conditions are issued for the Textron Aviation Inc. (Textron) Model 700 series airplanes. These airplanes will have novel or unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. These design features are 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 FAA's requirements. 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.

Federal Register, Volume 83 Issue 69 (Tuesday, April 10, 2018) 
[Federal Register Volume 83, Number 69 (Tuesday, April 10, 2018)]
[Rules and Regulations]
[Pages 15301-15304]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2018-07277]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2018-0293; Special Conditions No. 25-723-SC]


Special Conditions: Textron Aviation Inc. Model 700 Series 
Airplanes; Interaction 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 Textron Aviation 
Inc. (Textron) Model 700 series airplanes. These airplanes will have 
novel or unusual design features when compared to the state of 
technology envisioned in the airworthiness standards for transport 
category airplanes. These design features are 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 
FAA's requirements. 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: This action is effective on Textron Aviation Inc. on April 10, 
2018. Send comments on or before May 25, 2018.

ADDRESSES: Send comments identified by Docket No. FAA-2018-0293 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 website, 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).
    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 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: Greg Schneider, Airframe and Cabin 
Safety Section, AIR-675, Transport Standards Branch, Policy and 
Innovation Division, Aircraft Certification Service, Federal Aviation 
Administration, 2200 South 216th Street, Des Moines, Washington 98198; 
telephone 206-231-3213; email Greg.Schneider@faa.gov.

SUPPLEMENTARY INFORMATION: The substance of these special conditions 
previously has been published in the Federal Register for public 
comment. These special conditions have 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, the FAA has determined that prior public 
notice and comment are unnecessary, and finds that, for the same 
reason, good cause exists for adopting these special conditions upon 
publication in the Federal Register.

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 by the closing date for 
comments. We may change these special conditions based on the comments 
we receive.

Background

    On November 20, 2014, Textron applied for a type certificate for 
their new Model 700 series airplanes. The Textron Model 700 series 
airplanes are transport-category, twin turbofan-powered airplanes with 
standard seating provisions for up to 12 passengers and 2 crewmembers, 
and a maximum takeoff weight of 39,500 lbs.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.17, Textron must show that the Model 700 series airplanes meet 
the applicable provisions of part 25, as amended by amendments 25-1 
through 25-141.
    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 Textron Model 700 series airplanes 
because of novel or unusual design features, special conditions are

[[Page 15302]]

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 novel or 
unusual design features, these special conditions would also apply to 
the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Textron Model 700 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.
    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.

Novel or Unusual Design Features

    The Textron Model 700 series airplanes will incorporate the 
following novel or unusual design features:
    These airplanes are equipped with systems (i.e. with flight control 
systems, autopilots, stability augmentation systems, load alleviation 
systems, flutter control systems, fuel management systems, etc.) that, 
directly or as a result of failure or malfunction, affect its 
structural performance.

Discussion

    Current regulations do not take into account the effects of systems 
on structural performance including normal operation and failure 
conditions. Special conditions are needed to account for these 
features. These special conditions define criteria to be used in the 
assessment of the effects of these systems on structures. The general 
approach of accounting for the effect of system failures on structural 
performance is extended to include any system in which partial or 
complete failure, alone or in combination with other system partial or 
complete failures, would affect structural performance.
    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.

Applicability

    As discussed above, these special conditions are applicable to the 
Textron Model 700 series airplanes. Should Textron apply at a later 
date for a change to the type certificate to include another model 
incorporating the same novel or unusual design feature, these special 
conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on one 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.

Authority Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 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 Textron Aviation Inc. Model 700 series 
airplanes.

Interaction of Systems and Structures

    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, 
subpart C and D.
    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.
    1. The criteria defined herein only addresses 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 structures 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.
    2. 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 airplane to meet other realistic conditions, such as alternative 
gust or maneuver descriptions for an airplane equipped with a load 
alleviation system.
    3. The following definitions are applicable to these special 
conditions:
    a. Structural performance: Capability of the airplane to meet the 
structural requirements of 14 CFR part 25.
    b. 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, avoidance 
of severe weather conditions, etc.).
    c. 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).
    d. Probabilistic terms: The probabilistic terms (probable, 
improbable, extremely improbable) used in these special conditions are 
the same as those used in Sec.  25.1309.
    e. 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).
    4. General. The following criteria will be used in determining the 
influence of a system and its failure conditions on the airplane 
structure.
    5. System fully operative. With the system fully operative, the 
following apply:
    a. Limit loads must be derived in all normal operating 
configurations of the system from all the limit conditions specified in 
14 CFR part 25, subpart C (or defined by special condition or 
equivalent level of safety in lieu of those specified in part 25, 
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

[[Page 15303]]

conservative way when deriving limit loads from limit conditions.
    b. The airplane must meet the strength requirements of 14 CFR 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.
    c. The airplane must meet the aeroelastic stability requirements of 
Sec.  25.629.
    6. System in the failure condition. For any system failure 
condition not shown to be extremely improbable, the following apply:
    a. 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] TR10AP18.000

    ii. For residual strength substantiation, the airplane must be able 
to withstand two thirds of the ultimate loads defined in subparagraph 
(6)(a)(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 (oscillatory failures) must not produce loads that could 
result in detrimental deformation of primary structure.
    b. 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 condition 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:
    (1) The limit symmetrical maneuvering conditions specified in Sec.  
25.331 and in Sec.  25.345.
    (2) the limit gust and turbulence conditions specified in Sec.  
25.341 and in Sec.  25.345.
    (3) 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).
    (4) the limit yaw maneuvering conditions specified in Sec.  25.351.
    (5) 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 (6)(b)(i) of the 
special condition multiplied by a factor of safety depending on the 
probability of being in this failure state. The factor of safety is 
defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TR10AP18.001


[[Page 15304]]


Qj = (Tj)(Pj)

Where:

Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per 
hour)

    Note: If Pj is greater than 10-3 per 
flight hour then a 1.5 factor of safety must be applied to all limit 
load conditions specified in Subpart C.

    iii. For residual strength substantiation, the airplane must be 
able to withstand two thirds of the ultimate loads defined in paragraph 
(6)(b)(ii) of the special condition. 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] TR10AP18.002

V' = Clearance speed as defined by Sec.  25.629(b)(2).
V'' = Clearance speed as defined by Sec.  25.629(b)(1).
Qj = (Tj)(Pj) where:
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)

    Note: If Pj is greater than 10-3 per flight hour, 
then the flutter clearance speed must not be less than V''.

    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).
    c. 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 per flight hour, criteria 
other than those specified in this paragraph may be used for structural 
substantiation to show continued safe flight and landing.
    7. Failure indications. For system failure detection and 
indication, the following apply:
    a. 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 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.
    b. 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 14 CFR part 25, subpart C, below 1.25, or 
flutter margins below V'', must be signaled to the crew during flight.
    8. 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 this special 
condition must be met, including the provisions of paragraph (5) for 
the dispatched condition, and paragraph (6) 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 
flight hour.

    Issued in Des Moines, Washington.
Victor Wicklund,
Manager, Transport Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2018-07277 Filed 4-9-18; 8:45 am]
 BILLING CODE 4910-13-P

Federal Register / Vol. 83, No. 69 / Tuesday, April 10, 2018 / Rules and Regulations 15301 regulations to better serve the goals of to the state of technology envisioned in DC, between 9 a.m. and 5 p.m., Monday the CRA.’’ the airworthiness standards for through Friday, except Federal holidays. 4. On page 55736, the first full transport category airplanes. These FOR FURTHER INFORMATION CONTACT: Greg paragraph in the third column is revised design features are systems that affect Schneider, Airframe and Cabin Safety to read as follows: structural performance, either directly Section, AIR–675, Transport Standards ‘‘The Agencies received two or as a result of a failure or malfunction. Branch, Policy and Innovation Division, comments on the proposed changes to The influence of these systems and their Aircraft Certification Service, Federal the CRA public file content failure conditions must be taken into Aviation Administration, 2200 South requirements. One trade association account when showing compliance with 216th Street, Des Moines, Washington supported the Agencies’ efforts to the FAA’s requirements. The applicable 98198; telephone 206–231–3213; email streamline the public file content airworthiness regulations do not contain Greg.Schneider@faa.gov. requirements to make it consistent with adequate or appropriate safety standards SUPPLEMENTARY INFORMATION: The the new HMDA public disclosure for these design features. These special requirements. Another trade association substance of these special conditions conditions contain the additional safety previously has been published in the suggested that because financial standards that the Administrator institutions will no longer need to Federal Register for public comment. considers necessary to establish a level These special conditions have been provide HMDA Loan Application of safety equivalent to that established Registers to the public, financial derived without substantive change by the existing airworthiness standards. from those previously issued. It is institutions should also not be required DATES: This action is effective on to produce their CRA Loan Application unlikely that prior public comment Textron Aviation Inc. on April 10, 2018. would result in a significant change Registers (CRA LARs) so as to reduce Send comments on or before May 25, regulatory burden. Changing the from the substance contained herein. 2018. Therefore, the FAA has determined that requirements in the CRA public file with respect to CRA LARs would ADDRESSES: Send comments identified prior public notice and comment are require a regulation change that was not by Docket No. FAA–2018–0293 using unnecessary, and finds that, for the proposed by the Agencies and did not any of the following methods: same reason, good cause exists for have the benefit of notice and comment. • Federal eRegulations Portal: Go to adopting these special conditions upon Accordingly, the Agencies are adopting http://www.regulations.gov/ and follow publication in the Federal Register. the revisions as proposed.’’ the online instructions for sending your Comments Invited Dated: March 30, 2018. comments electronically. We invite interested people to take Joseph M. Otting, • Mail: Send comments to Docket part in this rulemaking by sending Comptroller of the Currency. Operations, M–30, U.S. Department of written comments, data, or views. The By order of the Board of Governors of the Transportation (DOT), 1200 New Jersey most helpful comments reference a Federal Reserve System, March 13, 2018. Avenue SE, Room W12–140, West specific portion of the special Ann E. Misback, Building Ground Floor, Washington, conditions, explain the reason for any DC, 20590–0001. recommended change, and include Secretary of the Board. • Hand Delivery or Courier: Take supporting data. Dated at Washington, DC, this 12th of March, 2018. comments to Docket Operations in We will consider all comments we Room W12–140 of the West Building receive by the closing date for By order of the Board of Directors. Ground Floor at 1200 New Jersey comments. We may change these special Federal Deposit Insurance Corporation. Avenue SE, Washington, DC, between 9 conditions based on the comments we Robert E. Feldman, a.m. and 5 p.m., Monday through Executive Secretary. receive. Friday, except Federal holidays. [FR Doc. 2018–06963 Filed 4–9–18; 8:45 am] • Fax: Fax comments to Docket Background BILLING CODE 4810–33; 6210–01; 6714–01–P Operations at 202–493–2251. On November 20, 2014, Textron Privacy: The FAA will post all applied for a type certificate for their comments it receives, without change, new Model 700 series airplanes. The DEPARTMENT OF TRANSPORTATION to http://www.regulations.gov/, Textron Model 700 series airplanes are including any personal information the transport-category, twin turbofan- Federal Aviation Administration commenter provides. Using the search powered airplanes with standard seating function of the docket website, anyone provisions for up to 12 passengers and 14 CFR Part 25 can find and read the electronic form of 2 crewmembers, and a maximum takeoff [Docket No. FAA–2018–0293; Special all comments received into any FAA weight of 39,500 lbs. Conditions No. 25–723–SC] docket, including the name of the individual sending the comment (or Type Certification Basis Special Conditions: Textron Aviation signing the comment for an association, Under the provisions of title 14, Code Inc. Model 700 Series Airplanes; business, labor union, etc.). DOT’s of Federal Regulations (14 CFR) 21.17, Interaction of Systems and Structures complete Privacy Act Statement can be Textron must show that the Model 700 AGENCY: Federal Aviation found in the Federal Register published series airplanes meet the applicable Administration (FAA), DOT. on April 11, 2000 (65 FR 19477–19478). provisions of part 25, as amended by ACTION: Final special conditions; request Docket: Background documents or amendments 25–1 through 25–141. jstallworth on DSKBBY8HB2PROD with RULES for comments. comments received may be read at If the Administrator finds that the http://www.regulations.gov/ at any time. applicable airworthiness regulations SUMMARY: These special conditions are Follow the online instructions for (i.e., 14 CFR part 25) do not contain issued for the Textron Aviation Inc. accessing the docket or go to Docket adequate or appropriate safety standards (Textron) Model 700 series airplanes. Operations in Room W12–140 of the for the Textron Model 700 series These airplanes will have novel or West Building Ground Floor at 1200 airplanes because of novel or unusual unusual design features when compared New Jersey Avenue SE, Washington, design features, special conditions are VerDate Sep<11>2014 14:31 Apr 09, 2018 Jkt 244001 PO 00000 Frm 00011 Fmt 4700 Sfmt 4700 E:\FR\FM\10APR1.SGM 10APR1

15302 Federal Register / Vol. 83, No. 69 / Tuesday, April 10, 2018 / Rules and Regulations prescribed under the provisions of another model incorporating the same in the system degraded or inoperative § 21.16. novel or unusual design feature, these mode are not provided in these special Special conditions are initially special conditions would apply to that conditions. applicable to the model for which they model as well. 2. Depending upon the specific are issued. Should the type certificate characteristics of the airplane, for that model be amended later to Conclusion additional studies may be required that include any other model that This action affects only certain novel go beyond the criteria provided in these incorporates the same novel or unusual or unusual design features on one model special conditions in order to design features, these special conditions series of airplanes. It is not a rule of demonstrate the capability of the would also apply to the other model general applicability. airplane to meet other realistic under § 21.101. List of Subjects in 14 CFR Part 25 conditions, such as alternative gust or In addition to the applicable maneuver descriptions for an airplane airworthiness regulations and special Aircraft, Aviation safety, Reporting equipped with a load alleviation system. conditions, the Textron Model 700 and recordkeeping requirements. 3. The following definitions are series airplanes must comply with the Authority Citation applicable to these special conditions: fuel vent and exhaust emission a. Structural performance: Capability requirements of 14 CFR part 34 and the The authority citation for these of the airplane to meet the structural noise certification requirements of 14 special conditions is as follows: requirements of 14 CFR part 25. CFR part 36. Authority: 49 U.S.C. 106(f), 106(g), 40113, b. Flight limitations: Limitations that The FAA issues special conditions, as 44701, 44702, 44704. can be applied to the airplane flight defined in 14 CFR 11.19, in accordance conditions following an in-flight The Special Conditions with § 11.38, and they become part of occurrence and that are included in the the type certification basis under Accordingly, pursuant to the flight manual (e.g., speed limitations, § 21.17. authority delegated to me by the avoidance of severe weather conditions, Administrator, the following special etc.). Novel or Unusual Design Features conditions are issued as part of the type c. Operational limitations: The Textron Model 700 series certification basis for Textron Aviation Limitations, including flight limitations airplanes will incorporate the following Inc. Model 700 series airplanes. that can be applied to the airplane novel or unusual design features: Interaction of Systems and Structures operating conditions before dispatch These airplanes are equipped with (e.g., fuel, payload and Master systems (i.e. with flight control systems, For airplanes equipped with systems Minimum Equipment List limitations). autopilots, stability augmentation that affect structural performance, either d. Probabilistic terms: The systems, load alleviation systems, flutter directly or as a result of a failure or probabilistic terms (probable, control systems, fuel management malfunction, the influence of these improbable, extremely improbable) used systems, etc.) that, directly or as a result systems and their failure conditions in these special conditions are the same of failure or malfunction, affect its must be taken into account when as those used in § 25.1309. structural performance. showing compliance with the e. Failure condition: The term failure requirements of title 14, Code of Federal condition is the same as that used in Discussion Regulations (14 CFR) part 25, subpart C § 25.1309, however these special Current regulations do not take into and D. conditions apply only to system failure account the effects of systems on The following criteria must be used conditions that affect the structural structural performance including for showing compliance with these performance of the airplane (e.g., system normal operation and failure conditions. special conditions for airplanes failure conditions that induce loads, Special conditions are needed to equipped with flight control systems, change the response of the airplane to account for these features. These special autopilots, stability augmentation inputs such as gusts or pilot actions, or conditions define criteria to be used in systems, load alleviation systems, flutter lower flutter margins). the assessment of the effects of these control systems, fuel management 4. General. The following criteria will systems on structures. The general systems, and other systems that either be used in determining the influence of approach of accounting for the effect of directly, or as a result of failure or a system and its failure conditions on system failures on structural malfunction, affect structural the airplane structure. performance is extended to include any performance. If these special conditions 5. System fully operative. With the system in which partial or complete are used for other systems, it may be system fully operative, the following failure, alone or in combination with necessary to adapt the criteria to the apply: other system partial or complete specific system. a. Limit loads must be derived in all failures, would affect structural 1. The criteria defined herein only normal operating configurations of the performance. addresses the direct structural system from all the limit conditions These special conditions contain the consequences of the system responses specified in 14 CFR part 25, subpart C additional safety standards that the and performances and cannot be (or defined by special condition or Administrator considers necessary to considered in isolation but should be equivalent level of safety in lieu of those establish a level of safety equivalent to included in the overall safety evaluation specified in part 25, subpart C), taking that established by the existing of the airplane. These criteria may, in into account any special behavior of airworthiness standards. some instances, duplicate standards such a system or associated functions or jstallworth on DSKBBY8HB2PROD with RULES already established for this evaluation. any effect on the structural performance Applicability These criteria are only applicable to of the airplane that may occur up to the As discussed above, these special structures whose failure could prevent limit loads. In particular, any significant conditions are applicable to the Textron continued safe flight and landing. nonlinearity (rate of displacement of Model 700 series airplanes. Should Specific criteria that define acceptable control surface, thresholds or any other Textron apply at a later date for a limits on handling characteristics or system nonlinearities) must be change to the type certificate to include stability requirements when operating accounted for in a realistic or VerDate Sep<11>2014 14:31 Apr 09, 2018 Jkt 244001 PO 00000 Frm 00012 Fmt 4700 Sfmt 4700 E:\FR\FM\10APR1.SGM 10APR1

Federal Register / Vol. 83, No. 69 / Tuesday, April 10, 2018 / Rules and Regulations 15303 conservative way when deriving limit conditions need not be considered when realistic scenario, including pilot loads from limit conditions. it can be shown that the airplane has corrective actions, must be established b. The airplane must meet the design features that will not allow it to to determine the loads occurring at the strength requirements of 14 CFR part 25 exceed those limit conditions. time of failure and immediately after (static strength, residual strength), using c. The airplane must meet the failure. the specified factors to derive ultimate aeroelastic stability requirements of loads from the limit loads defined i. For static strength substantiation, § 25.629. above. The effect of nonlinearities must 6. System in the failure condition. For these loads, multiplied by an be investigated beyond limit conditions any system failure condition not shown appropriate factor of safety that is to ensure the behavior of the system to be extremely improbable, the related to the probability of occurrence presents no anomaly compared to the following apply: of the failure, are ultimate loads to be behavior below limit conditions. a. At the time of occurrence. Starting considered for design. The factor of However, conditions beyond limit from 1-g level flight conditions, a safety (FS) is defined in Figure 1. ii. For residual strength loads that could result in detrimental (2) the limit gust and turbulence substantiation, the airplane must be able deformation of primary structure. conditions specified in § 25.341 and in to withstand two thirds of the ultimate b. For the continuation of the flight. § 25.345. loads defined in subparagraph (6)(a)(i). For the airplane, in the system failed (3) the limit rolling conditions For pressurized cabins, these loads must state and considering any appropriate specified in § 25.349 and the limit be combined with the normal operating unsymmetrical conditions specified in reconfiguration and flight limitations, differential pressure. § 25.367 and § 25.427(b) and (c). the following apply: (4) the limit yaw maneuvering iii. Freedom from aeroelastic i. The loads derived from the conditions specified in § 25.351. instability must be shown up to the following conditions (or defined by (5) the limit ground loading speeds defined in § 25.629(b)(2). For special condition or equivalent level of conditions specified in §§ 25.473, failure conditions that result in speeds safety in lieu of the following 25.491, 25.493(d) and 25.503. beyond VC/MC, freedom from conditions) at speeds up to VC/MC, or ii. For static strength substantiation, aeroelastic instability must be shown to each part of the structure must be able the speed limitation prescribed for the increased speeds, so that the margins to withstand the loads in paragraph remainder of the flight, must be intended by § 25.629(b)(2) are (6)(b)(i) of the special condition determined: maintained. multiplied by a factor of safety (1) The limit symmetrical iv. Failures of the system that result depending on the probability of being in maneuvering conditions specified in in forced structural vibrations this failure state. The factor of safety is § 25.331 and in § 25.345. (oscillatory failures) must not produce defined in Figure 2. jstallworth on DSKBBY8HB2PROD with RULES ER10AP18.001</GPH> ER10AP18.000</GPH> VerDate Sep<11>2014 14:31 Apr 09, 2018 Jkt 244001 PO 00000 Frm 00013 Fmt 4700 Sfmt 4725 E:\FR\FM\10APR1.SGM 10APR1

15304 Federal Register / Vol. 83, No. 69 / Tuesday, April 10, 2018 / Rules and Regulations Qj = (Tj)(Pj) iii. For residual strength fatigue or damage tolerance then their Where: substantiation, the airplane must be able effects must be taken into account. Tj = Average time spent in failure condition to withstand two thirds of the ultimate v. Freedom from aeroelastic j (in hours) loads defined in paragraph (6)(b)(ii) of instability must be shown up to a speed Pj = Probability of occurrence of failure mode the special condition. For pressurized determined from Figure 3. Flutter j (per hour) cabins, these loads must be combined clearance speeds V′ and V″ may be Note: If Pj is greater than 10¥3 per flight with the normal operating differential based on the speed limitation specified hour then a 1.5 factor of safety must be pressure. iv. If the loads induced by the failure for the remainder of the flight using the applied to all limit load conditions specified in Subpart C. condition have a significant effect on margins defined by § 25.629(b). V′ = Clearance speed as defined by may use special periodic inspections, determining the safety margin in Figure § 25.629(b)(2). and electronic components may use 1. Flight limitations and expected V″ = Clearance speed as defined by daily checks, in lieu of detection and operational limitations may be taken § 25.629(b)(1). indication systems to achieve the into account in establishing Qj as the Qj = (Tj)(Pj) where: Tj = Average time spent in failure condition objective of this requirement. These combined probability of being in the j (in hours) certification maintenance requirements dispatched failure condition and the Pj = Probability of occurrence of failure mode must be limited to components that are subsequent failure condition for the j (per hour) not readily detectable by normal safety margins in Figures 2 and 3. These Note: If Pj is greater than 10¥3 per flight detection and indication systems and limitations must be such that the hour, then the flutter clearance speed must where service history shows that probability of being in this combined not be less than V″. inspections will provide an adequate failure state and then subsequently vi. Freedom from aeroelastic level of safety. encountering limit load conditions is instability must also be shown up to V′ b. The existence of any failure extremely improbable. No reduction in in Figure 3 above, for any probable condition, not extremely improbable, these safety margins is allowed if the system failure condition combined with during flight that could significantly subsequent system failure rate is greater any damage required or selected for affect the structural capability of the than 10¥3 per flight hour. investigation by § 25.571(b). airplane and for which the associated Issued in Des Moines, Washington. c. Consideration of certain failure reduction in airworthiness can be Victor Wicklund, conditions may be required by other minimized by suitable flight limitations, must be signaled to the flight crew. For Manager, Transport Standards Branch, Policy sections of 14 CFR part 25 regardless of and Innovation Division, Aircraft calculated system reliability. Where example, failure conditions that result Certification Service. analysis shows the probability of these in a factor of safety between the airplane [FR Doc. 2018–07277 Filed 4–9–18; 8:45 am] failure conditions to be less than 10¥9 strength and the loads of 14 CFR part BILLING CODE 4910–13–P per flight hour, criteria other than those 25, subpart C, below 1.25, or flutter specified in this paragraph may be used margins below V″, must be signaled to for structural substantiation to show the crew during flight. DEPARTMENT OF TRANSPORTATION continued safe flight and landing. 8. Dispatch with known failure 7. Failure indications. For system conditions. If the airplane is to be Federal Aviation Administration failure detection and indication, the dispatched in a known system failure following apply: condition that affects structural 14 CFR Part 25 a. The system must be checked for performance, or affects the reliability of failure conditions, not extremely the remaining system to maintain [Docket No. FAA–2018–0247; Special improbable, that degrade the structural structural performance, then the Conditions No. 25–721–SC] capability below the level required by provisions of this special condition jstallworth on DSKBBY8HB2PROD with RULES part 25 or significantly reduce the must be met, including the provisions of Special Conditions: Textron Aviation reliability of the remaining system. As paragraph (5) for the dispatched Inc. Model 700 Series Airplanes; Side- far as reasonably practicable, the flight condition, and paragraph (6) for Facing Seats—Installation of Airbag crew must be made aware of these subsequent failures. Expected Systems failures before flight. Certain elements operational limitations may be taken of the control system, such as into account in establishing Pj as the AGENCY:Federal Aviation ER10AP18.002</GPH> mechanical and hydraulic components, probability of failure occurrence for Administration (FAA), DOT. VerDate Sep<11>2014 14:31 Apr 09, 2018 Jkt 244001 PO 00000 Frm 00014 Fmt 4700 Sfmt 4700 E:\FR\FM\10APR1.SGM 10APR1


Document Created: 2018-04-09 23:51:36
Document Modified: 2018-04-09 23:51:36
CategoryRegulatory Information
CollectionFederal Register
sudoc ClassAE 2.7:
GS 4.107:
AE 2.106:
PublisherOffice of the Federal Register, National Archives and Records Administration
SectionRules and Regulations
ActionFinal special conditions; request for comments.
DatesThis action is effective on Textron Aviation Inc. on April 10, 2018. Send comments on or before May 25, 2018.
ContactGreg Schneider, Airframe and Cabin Safety Section, AIR-675, Transport Standards Branch, Policy and Innovation Division, Aircraft Certification Service, Federal Aviation Administration, 2200 South 216th Street, Des Moines, Washington 98198; telephone 206-231-3213; email [email protected]
FR Citation83 FR 15301 
CFR AssociatedAircraft; Aviation Safety and Reporting and Recordkeeping Requirements
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