Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model 525 Helicopters; Flight Envelope Protection, 51623-51624 [2018-22267]
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51623
Rules and Regulations
Federal Register
Vol. 83, No. 198
Friday, October 12, 2018
This section of the FEDERAL REGISTER
contains regulatory documents having general
applicability and legal effect, most of which
are keyed to and codified in the Code of
Federal Regulations, which is published under
50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by
the Superintendent of Documents.
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 29
[Docket No.FAA–2017–1127; Notice No. 29–
044–SC]
Special Conditions: Bell Helicopter
Textron, Inc. (BHTI), Model 525
Helicopters; Flight Envelope
Protection
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
These special conditions are
issued for the BHTI Model 525
helicopter. This helicopter will have a
novel or unusual design feature
associated with fly-by-wire flight
control system (FBW FCS) flight
envelope protection. 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: These special conditions are
effective November 13, 2018.
FOR FURTHER INFORMATION CONTACT:
George Harrum, Aerospace Engineer,
FAA, Rotorcraft Standards Branch,
Policy and Innovation Division, 10101
Hillwood Pkwy., Fort Worth, TX 76177;
telephone (817) 222–4087; email
George.Harrum@faa.gov.
SUPPLEMENTARY INFORMATION:
SUMMARY:
khammond on DSK30JT082PROD with RULES
Background
On December 15, 2011, BHTI applied
for a type certificate for a new transport
category helicopter designated as the
Model 525. The Model 525 is a medium
twin-engine rotorcraft. The design
maximum takeoff weight is 20,500
pounds, with a maximum capacity of 19
passengers and a crew of 2.
VerDate Sep<11>2014
16:22 Oct 11, 2018
Jkt 247001
The BHTI Model 525 helicopter will
be equipped with a four axis full
authority digital FBW FCS that provides
for aircraft control through pilot input
and coupled flight director modes. The
FBW FCS will contain an advanced
flight control system that will alter the
nominal flight control laws to ensure
that the aircraft remains in a
predetermined flight envelope. These
Flight Envelope Protection (FEP)
features prevent the pilot or autopilot
functions from making control
commands that would force the aircraft
to exceed its structural, aerodynamic, or
operating limits. The design and
construction standards, specifically 14
CFR Section 29.779(a), require that
movement of the flight controls results
in a corresponding sense of aircraft
motion in the same axis. The
airworthiness standards for an
automatic pilot system in Section
29.1329 covers design requirements for
basic operation of the system but does
not address dynamic flight envelope
limitations imposed by the automatic
pilot system. Currently there are no
specific airworthiness requirements that
address FBW FCS FEP in rotorcraft. The
special conditions will require the
minimum safety standard for the FEP
features.
Type Certification Basis
Under the provisions of 14 CFR 21.17,
BHTI must show that the Model 525
helicopter meets the applicable
provisions of part 29, as amended by
Amendment 29–1 through 29–55
thereto. The BHTI Model 525
certification basis date is December 31,
2013, the effective date of application to
the FAA.
If the Administrator finds that the
applicable airworthiness regulations
(i.e., 14 CFR part 29) do not contain
adequate or appropriate safety standards
for the BHTI Model 525 because of a
novel or unusual design feature, special
conditions are prescribed under the
provisions of § 21.16.
Special conditions are initially
applicable to the model for which they
are issued. Should the type certificate
for that model be amended later to
include any other model that
incorporates the same or similar novel
or unusual design feature, the special
conditions would also apply to the other
model under § 21.101.
In addition to the applicable
airworthiness regulations and special
PO 00000
Frm 00001
Fmt 4700
Sfmt 4700
conditions, the BHTI Model 525
helicopter must comply with the noise
certification requirements of 14 CFR
part 36, and the FAA must issue a
finding of regulatory adequacy under
§ 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 § 11.38, and they become part of
the type-certification basis under
§ 21.17(a)(2).
Novel or Unusual Design Features
The BHTI Model 525 helicopter will
incorporate the following novel or
unusual design features: FBW FCS
incorporating FEP features. FEP is used
to prevent the pilot or an autopilot from
making control commands that would
force the rotorcraft to exceed its
structural, aerodynamic, or operating
limits. To accomplish this envelope
limiting, the FCS control laws change as
the limit is approached or exceeded.
Discussion
These special conditions require the
minimum safety standard for the flight
envelope protection features. The FEP
features must meet requirements for
handling qualities, compatibility of
flight parameter limit values, response
to dynamic maneuvering, and failure
modes.
Discussion of Comments
Notice of proposed special conditions
No. 29–044–SC for the BHTI Model 525
helicopter was published in the Federal
Register on June 6, 2018 (83 FR 26226).
No comments were received, and the
special conditions are adopted as
proposed.
Applicability
As discussed above, these special
conditions are applicable to the BHTI
Model 525 helicopter. Should BHTI
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 one model
of rotorcraft. It is not a rule of general
applicability.
E:\FR\FM\12OCR1.SGM
12OCR1
51624
Federal Register / Vol. 83, No. 198 / Friday, October 12, 2018 / Rules and Regulations
List of Subjects in 14 CFR Part 29
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.
khammond on DSK30JT082PROD with RULES
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 Bell Helicopter
Textron, Inc., Model 525 helicopters:
Flight Envelope Protection
The Flight Envelope Protection (FEP)
features of the flight control system
(FCS) must meet the following
requirements:
a. Onset characteristics of each
envelope protection feature must be
smooth, appropriate to the phase of
flight and type of maneuver, and not in
conflict with the ability of the pilot to
satisfactorily change rotorcraft flight
path, speed, or attitude within the
approved flight envelope.
b. Limit values of protected flight
parameters (and if applicable, associated
warning thresholds) must be compatible
with:
1. Rotorcraft structural limits;
2. Safe and controllable maneuvering
of the rotorcraft;
3. Margins to critical conditions.
Dynamic maneuvering, airframe and
system tolerances (both manufacturing
and in-service), and non-steady
atmospheric conditions—in any
appropriate combination and phase of
flight—must not result in a limited
flight parameter beyond the nominal
design limit value that would cause
unsafe flight characteristics;
4. Rotor rotational speed limits;
5. Blade stall limits; and
6. Engine and transmission torque
limits.
c. The aircraft must be responsive to
pilot-commanded dynamic
maneuvering within a suitable range of
the parameter limits that define the
approved flight envelope.
d. The FEP system must not create
unusual or adverse flight characteristics
when atmospheric conditions or
unintentional pilot action causes the
approved flight envelope to be
exceeded.
e. When simultaneous envelope
limiting is active, adverse coupling or
adverse priority must not result.
f. Following a single FEP failure
shown to not be extremely improbable,
the rotorcraft must:
1. Be capable of continued safe flight
and landing;
VerDate Sep<11>2014
16:22 Oct 11, 2018
Jkt 247001
2. Be capable of initial counteraction
of malfunctions without requiring
exceptional pilot skill or strength;
3. Be controllable and maneuverable
when operated with a degraded FCS,
within a practical flight envelope
identified in the Rotorcraft Flight
Manual;
4. Be capable of prolonged instrument
flight without requiring exceptional
pilot skill;
5. Meet the controllability and
maneuverability requirements of 14 CFR
part 29 Subpart B throughout a practical
flight envelope; and
6. Be safely controllable following any
additional failure or malfunction shown
to not be extremely improbable
occurring within the approved flight
envelope.
Issued in Fort Worth, Texas, on October 3,
2018.
Jorge Castillo,
Acting Manager, Rotorcraft Standards
Branch, Policy and Innovation Division,
Aircraft Certification Services.
[FR Doc. 2018–22267 Filed 10–11–18; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 29
[Docket No.FAA–2017–1128; Notice No. 29–
045–SC]
Special Conditions: Bell Helicopter
Textron, Inc. (BHTI), Model 525
Helicopters; Control Margin
Awareness
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
These special conditions are
issued for the BHTI Model 525
helicopter. This helicopter will have a
novel or unusual design feature
associated with the fly-by-wire flight
control system (FBW FCS) in the area of
pilot awareness of the control margins
remaining while maneuvering the
helicopter. 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: These special conditions are
effective November 13, 2018.
FOR FURTHER INFORMATION CONTACT:
George Harrum, Aerospace Engineer,
SUMMARY:
PO 00000
Frm 00002
Fmt 4700
Sfmt 4700
FAA, Rotorcraft Standards Branch,
Policy and Innovation Division, 10101
Hillwood Pkwy., Fort Worth, TX 76177;
telephone (817) 222–4087; email
George.Harrum@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
On December 15, 2011, BHTI applied
for a type certificate for a new transport
category helicopter designated as the
Model 525. The Model 525 is a medium
twin-engine rotorcraft. The design
maximum takeoff weight is 20,500
pounds, with a maximum capacity of 19
passengers and a crew of 2.
The BHTI Model 525 helicopter will
be equipped with a four-axis full
authority digital FBW FCS that provides
for aircraft control through pilot input
and coupled flight director modes. The
current 14 CFR part 29 regulations do
not contain adequate standards for FBW
FCS with respect to control margin
awareness. The airworthiness standards
for controllability and maneuverability
of the rotorcraft are contained in
§ 29.143. These controllability
requirements are compatible with most
FBW systems, while most of the
maneuverability requirements are not
affected by FBW systems, except for the
control margins. One of the purposes of
the rule is to ensure that control margins
(at the rotor and the anti-torque system
level) are sufficient in the defined flight
envelope to avoid loss of control (that is,
the rotorcraft has adequate control
power for the pilot to exit potentially
hazardous flight conditions). Implicit in
this purpose is that the pilot is provided
with sufficient awareness of proximity
to control limits. Because § 29.143 was
written to address hydro-mechanical
flight control systems, through which
pilot awareness of control margins is
provided by cyclic and pedal position
relative to cockpit control stops, the rule
is inadequate for certification of a FBW
FCS, where there is no mechanical link
between the inceptor and the receptor.
Without a constant correlation between
cockpit control and main or tail rotor
actuator positions, the FCS may not
provide tactile control margin feedback
to the pilot through cockpit control
position relative to the control position
physical stop or limit, for all flight
conditions. The special conditions will
require the minimum safety standard to
ensure awareness of proximity to
control limits at the main rotor and tail
rotor is provided to pilots of the Bell
Model 525 helicopter.
Type Certification Basis
Under the provisions of 14 CFR 21.17,
BHTI must show that the Model 525
helicopter meets the applicable
E:\FR\FM\12OCR1.SGM
12OCR1
]]>Agencies
[Federal Register Volume 83, Number 198 (Friday, October 12, 2018)]
[Rules and Regulations]
[Pages 51623-51624]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-22267]
========================================================================
Rules and Regulations
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains regulatory documents
having general applicability and legal effect, most of which are keyed
to and codified in the Code of Federal Regulations, which is published
under 50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by the Superintendent of Documents.
========================================================================
Federal Register / Vol. 83, No. 198 / Friday, October 12, 2018 /
Rules and Regulations
[[Page 51623]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 29
[Docket No.FAA-2017-1127; Notice No. 29-044-SC]
Special Conditions: Bell Helicopter Textron, Inc. (BHTI), Model
525 Helicopters; Flight Envelope Protection
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for the BHTI Model 525
helicopter. This helicopter will have a novel or unusual design feature
associated with fly-by-wire flight control system (FBW FCS) flight
envelope protection. 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: These special conditions are effective November 13, 2018.
FOR FURTHER INFORMATION CONTACT: George Harrum, Aerospace Engineer,
FAA, Rotorcraft Standards Branch, Policy and Innovation Division, 10101
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-4087; email
[email protected].
SUPPLEMENTARY INFORMATION:
Background
On December 15, 2011, BHTI applied for a type certificate for a new
transport category helicopter designated as the Model 525. The Model
525 is a medium twin-engine rotorcraft. The design maximum takeoff
weight is 20,500 pounds, with a maximum capacity of 19 passengers and a
crew of 2.
The BHTI Model 525 helicopter will be equipped with a four axis
full authority digital FBW FCS that provides for aircraft control
through pilot input and coupled flight director modes. The FBW FCS will
contain an advanced flight control system that will alter the nominal
flight control laws to ensure that the aircraft remains in a
predetermined flight envelope. These Flight Envelope Protection (FEP)
features prevent the pilot or autopilot functions from making control
commands that would force the aircraft to exceed its structural,
aerodynamic, or operating limits. The design and construction
standards, specifically 14 CFR Section 29.779(a), require that movement
of the flight controls results in a corresponding sense of aircraft
motion in the same axis. The airworthiness standards for an automatic
pilot system in Section 29.1329 covers design requirements for basic
operation of the system but does not address dynamic flight envelope
limitations imposed by the automatic pilot system. Currently there are
no specific airworthiness requirements that address FBW FCS FEP in
rotorcraft. The special conditions will require the minimum safety
standard for the FEP features.
Type Certification Basis
Under the provisions of 14 CFR 21.17, BHTI must show that the Model
525 helicopter meets the applicable provisions of part 29, as amended
by Amendment 29-1 through 29-55 thereto. The BHTI Model 525
certification basis date is December 31, 2013, the effective date of
application to the FAA.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 29) do not contain adequate or
appropriate safety standards for the BHTI Model 525 because of a novel
or unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the special conditions would also
apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the BHTI Model 525 helicopter must comply with 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 BHTI Model 525 helicopter will incorporate the following novel
or unusual design features: FBW FCS incorporating FEP features. FEP is
used to prevent the pilot or an autopilot from making control commands
that would force the rotorcraft to exceed its structural, aerodynamic,
or operating limits. To accomplish this envelope limiting, the FCS
control laws change as the limit is approached or exceeded.
Discussion
These special conditions require the minimum safety standard for
the flight envelope protection features. The FEP features must meet
requirements for handling qualities, compatibility of flight parameter
limit values, response to dynamic maneuvering, and failure modes.
Discussion of Comments
Notice of proposed special conditions No. 29-044-SC for the BHTI
Model 525 helicopter was published in the Federal Register on June 6,
2018 (83 FR 26226). No comments were received, and the special
conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
BHTI Model 525 helicopter. Should BHTI 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 one model of rotorcraft. It is not a rule of general applicability.
[[Page 51624]]
List of Subjects in 14 CFR Part 29
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 Bell Helicopter Textron, Inc., Model
525 helicopters:
Flight Envelope Protection
The Flight Envelope Protection (FEP) features of the flight control
system (FCS) must meet the following requirements:
a. Onset characteristics of each envelope protection feature must
be smooth, appropriate to the phase of flight and type of maneuver, and
not in conflict with the ability of the pilot to satisfactorily change
rotorcraft flight path, speed, or attitude within the approved flight
envelope.
b. Limit values of protected flight parameters (and if applicable,
associated warning thresholds) must be compatible with:
1. Rotorcraft structural limits;
2. Safe and controllable maneuvering of the rotorcraft;
3. Margins to critical conditions. Dynamic maneuvering, airframe
and system tolerances (both manufacturing and in-service), and non-
steady atmospheric conditions--in any appropriate combination and phase
of flight--must not result in a limited flight parameter beyond the
nominal design limit value that would cause unsafe flight
characteristics;
4. Rotor rotational speed limits;
5. Blade stall limits; and
6. Engine and transmission torque limits.
c. The aircraft must be responsive to pilot-commanded dynamic
maneuvering within a suitable range of the parameter limits that define
the approved flight envelope.
d. The FEP system must not create unusual or adverse flight
characteristics when atmospheric conditions or unintentional pilot
action causes the approved flight envelope to be exceeded.
e. When simultaneous envelope limiting is active, adverse coupling
or adverse priority must not result.
f. Following a single FEP failure shown to not be extremely
improbable, the rotorcraft must:
1. Be capable of continued safe flight and landing;
2. Be capable of initial counteraction of malfunctions without
requiring exceptional pilot skill or strength;
3. Be controllable and maneuverable when operated with a degraded
FCS, within a practical flight envelope identified in the Rotorcraft
Flight Manual;
4. Be capable of prolonged instrument flight without requiring
exceptional pilot skill;
5. Meet the controllability and maneuverability requirements of 14
CFR part 29 Subpart B throughout a practical flight envelope; and
6. Be safely controllable following any additional failure or
malfunction shown to not be extremely improbable occurring within the
approved flight envelope.
Issued in Fort Worth, Texas, on October 3, 2018.
Jorge Castillo,
Acting Manager, Rotorcraft Standards Branch, Policy and Innovation
Division, Aircraft Certification Services.
[FR Doc. 2018-22267 Filed 10-11-18; 8:45 am]
BILLING CODE 4910-13-P
