Home/Federal/Federal Register/2022-06178

Rule2022-06178

Special Conditions: Dassault Aviation Model Falcon 6X Airplane; Interaction of Systems and Structures

Primary source

Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.

Published

March 24, 2022

Effective

March 24, 2022

Issuing agencies

Transportation DepartmentFederal Aviation Administration

Abstract

These special conditions are issued for the Dassault Aviation (Dassault) Model Falcon 6X airplane. This airplane will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. This design feature is installed systems that, directly or as a result of failure or malfunction, affect airplane structural performance. 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.

Full Text

<html>
<head>
<title>Federal Register, Volume 87 Issue 57 (Thursday, March 24, 2022)</title>
</head>
<body><pre>
[Federal Register Volume 87, Number 57 (Thursday, March 24, 2022)]
[Rules and Regulations]
[Pages 16626-16630]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-06178]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-FAA-2021-0630; Special Conditions No. 25-801-SC]

Special Conditions: Dassault Aviation Model Falcon 6X Airplane;
Interaction of Systems and Structures

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for the Dassault Aviation
(Dassault) Model Falcon 6X airplane. This airplane will have a novel or
unusual design feature when compared to the state of technology
envisioned in the airworthiness standards for transport category
airplanes. This design feature is installed systems that, directly or
as a result of failure or malfunction, affect airplane structural
performance. 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: This action is effective on Dassault on March 24, 2022. Send
comments on or before May 9, 2022.

ADDRESSES: Send comments identified by Docket No. FAA-2021-0630 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="http://www.regulations.gov/">http://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> 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.
<bullet> 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.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: Except for Confidential Business Information (CBI) as
described in the following paragraph, and other information as
described in 14 CFR 11.35, the FAA will post all comments received
without change to <a href="http://www.regulations.gov/">http://www.regulations.gov/</a>, including any personal
information you provide. The FAA will also post a report summarizing
each substantive verbal contact received about these special
conditions.
Confidential Business Information: Confidential Business
Information (CBI) is commercial or financial information that is both
customarily and actually treated as private by its owner. Under the
Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from
public disclosure. If your comments responsive to these special
conditions contain commercial or financial information that is
customarily treated as private, that you actually treat as private, and
that is relevant or responsive to these special conditions, it is
important that you clearly designate the submitted comments as CBI.
Please mark each page of your submission containing CBI as ``PROPIN.''
The FAA

[[Page 16627]]

will treat such marked submissions as confidential under the FOIA, and
the indicated comments will not be placed in the public docket of these
special conditions. Send submissions containing CBI to the Information
Contact below. Comments the FAA receives, which are not specifically
designated as CBI, will be placed in the public docket for these
special conditions.
Docket: Background documents or comments received may be read at
<a href="http://www.regulations.gov/">http://www.regulations.gov/</a> 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: Todd Martin, Materials and Structural
Properties Section, AIR-621, Technical Innovation Policy Branch, Policy
and Innovation Division, Aircraft Certification Service, Federal
Aviation Administration, 2200 South 216th Street, Des Moines,
Washington 98198; telephone and fax 206-231-3210; email
<a href="/cdn-cgi/l/email-protection#e5918a8181cb888497918c8ba5838484cb828a93">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: The substance of these special conditions
has been published in the Federal Register for public comment in
several prior instances with no substantive comments received.
Therefore, the FAA finds, pursuant to Sec. 11.38(b), that new comments
are unlikely, and notice and comment prior to this publication are
unnecessary.

Comments Invited

The FAA invites 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.
The FAA will consider all comments received by the closing date for
comments. The FAA may change these special conditions based on the
comments received.

Background

On February 1, 2018, Dassault applied for a type certificate for
their new Model Falcon 6X airplane. This airplane is a twin-engine
business jet with seating for 19 passengers and a maximum takeoff
weight of 77,460 pounds.

Type Certification Basis

Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.17, Dassault must show that the Model Falcon 6X airplane meets
the applicable provisions of part 25, as amended by amendments 25-1
through 25-146.
If the Administrator finds that the applicable airworthiness
regulations (e.g., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Dassault Model Falcon 6X airplane
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 novel or
unusual design feature, 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 Dassault Model Falcon 6X airplane 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(a)(2).

Novel or Unusual Design Features

The Dassault Model Falcon 6X airplane will incorporate the
following novel or unusual design feature:
Installed systems that, directly or as a result of failure or
malfunction, affect airplane structural performance.

Discussion

The Dassault Model Falcon 6X airplane is equipped with systems that
directly, or as a result of failure or malfunction, affect its
structural performance. These systems include the digital flight-
control system, which includes maneuver-load and gust-load alleviation,
and the fuel-management system. Current FAA 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.
These special conditions are similar to those previously applied to
other airplane models.

Applicability

As discussed above, these special conditions are applicable to the
Dassault Model Falcon 6X airplane. Should Dassault 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 a certain novel or unusual design feature
on one model of airplane. 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 the Dassault Model Falcon 6X airplane.
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 14 CFR part 25 subparts 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 address the direct structural

[[Page 16628]]

consequences of the system responses and performance. They 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 the failure of which 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 that go beyond the criteria provided in these
special conditions may be required to demonstrate the airplane's
capability 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 airplane 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: Terms such as probable, improbable, and
extremely improbable, as used in these special conditions, are the same
as those used in Sec. 25.1309.
e. Failure condition: This term 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).

Effects of Systems on Structures

The following criteria will be used in determining the influence of
a system and its failure conditions on the airplane structure.
1. 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 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.
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
that 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.
2. 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 1g 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 the 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 is defined in Figure 1, below.
[GRAPHIC] [TIFF OMITTED] TR24MR22.060

ii. For residual-strength substantiation, the airplane must be able
to withstand two-thirds of the ultimate loads defined in special
condition 2.a.i above. 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 V<INF>C</INF>/M<INF>C</INF>, 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:

[[Page 16629]]

i. The loads derived from the following conditions (or used in lieu
of the following conditions) at speeds up to V<INF>C</INF>/
M<INF>C</INF> (or the speed limitation prescribed for the remainder of
the flight) must be determined:
1. The limit symmetrical maneuvering conditions specified in
Sec. Sec. 25.331 and 25.345.
2. The limit gust and turbulence conditions specified in Sec. Sec.
25.341 and 25.345.
3. The limit rolling conditions specified in Sec. 25.349, and the
limit unsymmetrical conditions specified in Sec. Sec. 25.367, and
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 and 25.491.
ii. For static-strength substantiation, each part of the structure
must be able to withstand the loads in special condition 2.b.i.,
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,
below.
[GRAPHIC] [TIFF OMITTED] TR24MR22.061

Q <INF>j</INF> = (T<INF>j</INF>)(P<INF>j</INF>)

Where:

Q <INF>j</INF> = Probability of being in failure mode j
T<INF>j</INF> = Average time spent in failure mode j (in hours)
P<INF>j</INF> = Probability of occurrence of failure mode j (per
hour)

Note: If P<INF>j</INF> 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 14
CFR part 25, subpart C.

iii. For residual-strength substantiation, the airplane must be
able to withstand two-thirds of the ultimate loads defined in special
condition 2.b.ii. 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, below. 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] TR24MR22.062

V' = Clearance speed as defined by Sec. 25.629(b)(2).
V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Q <INF>j</INF> = (T<INF>j</INF>)(P<INF>j</INF>)
where:

Q <INF>j</INF> = Probability of being in failure mode j
T<INF>j</INF> = Average time spent in failure mode j (in hours)
P<INF>j</INF> = Probability of occurrence of failure mode j (per
hour)

Note: If P<INF>j</INF> 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.
3. Failure indications. For system-failure detection and
indication, the following apply:
a. The system must be checked for failure conditions, not extremely

[[Page 16630]]

improbable, that degrade the structural capability below the level
required by part 25, or that significantly reduce the reliability of
the remaining system. As far as reasonably practicable, the flightcrew
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 flightcrew. For example, failure
conditions that result in a factor of safety between the airplane
strength and the loads of part 25, subpart C, below 1.25, or flutter
margins below V'', must be signaled to the crew during flight.
4. Dispatch with known failure conditions. If the airplane is to be
dispatched in a known system-failure condition that affects structural
performance, or that 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 special condition
1, ``System Fully Operative'' for the dispatched condition, and special
condition 2, ``System in the Failure Condition'' for subsequent
failures. Expected operational limitations may be taken into account in
establishing P<INF>j</INF> 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 Q<INF>j</INF> 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 Kansas City, Missouri, on March 18, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2022-06178 Filed 3-23-22; 8:45 am]
BILLING CODE 4910-13-P

</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>

View on FederalRegister.gov →Plain-text source

Indexed from Federal Register on March 24, 2022.

This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.