[Federal Register Volume 87, Number 224 (Tuesday, November 22, 2022)]
[Rules and Regulations]
[Pages 71203-71210]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-25291]
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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.
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Federal Register / Vol. 87 , No. 224 / Tuesday, November 22, 2022 /
Rules and Regulations
[[Page 71203]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No.: FAA-2018-0653; Amdt. No. 25-147]
RIN 2120-AK89
Yaw Maneuver Conditions--Rudder Reversals
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adding a new load condition to the design standards
for transport category airplanes. The new load condition requires such
airplanes to be designed to withstand the loads caused by rapid
reversals of the rudder pedals, and applies to transport category
airplanes that have a powered rudder control surface or surfaces. This
rule is necessary because accident and incident data show that pilots
sometimes make rudder reversals during flight, even though such
reversals are unnecessary and discouraged by flightcrew training
programs. The current design standards do not require the airplane
structure to withstand the loads that may result from such reversals.
If the loads on the airplane exceed those for which it is designed, the
airplane structure may fail, resulting in catastrophic loss of control
of the airplane. This final rule aims to prevent structural failure of
the rudder and vertical stabilizer that may result from these rudder
reversals.
DATES: Effective January 23, 2023.
ADDRESSES: For information on where to obtain copies of rulemaking
documents and other information related to this final rule, see ``How
To Obtain Additional Information'' in the SUPPLEMENTARY INFORMATION
section of this document.
FOR FURTHER INFORMATION CONTACT: For technical questions concerning
this action, contact Todd Martin, Materials and Structural Properties
Section, AIR-621, Policy and Innovation Division, Aircraft
Certification Service, Federal Aviation Administration, 2200 South
216th Street, Des Moines, WA 98198; telephone and fax (206) 231-3210;
email [email protected].
SUPPLEMENTARY INFORMATION:
Authority for This Rulemaking
The FAA's authority to issue rules on aviation safety is found in
Title 49 of the United States Code. Subtitle I, Section 106 describes
the authority of the FAA Administrator. Subtitle VII, Aviation
Programs, describes in more detail the scope of the agency's authority.
This rulemaking is promulgated under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, ``General
Requirements.'' Under that section, the FAA is charged with promoting
safe flight of civil aircraft in air commerce by prescribing
regulations and minimum standards for the design and performance of
aircraft that the Administrator finds necessary for safety in air
commerce. This regulation is within the scope of that authority. It
prescribes new safety standards for the design of transport-category
airplanes.
I. Overview of Final Rule
This rule adds a new load condition to the design standards in
title 14, Code of Federal Regulations (14 CFR) part 25, to require
transport category airplanes that have a powered rudder control surface
or surfaces to be designed to withstand the loads caused by rapid
reversals of the rudder pedals. Specifically, applicants for design
approval must show that their proposed airplane design can withstand an
initial full rudder pedal input, followed by three full-pedal reversals
at the maximum sideslip angle, followed by return of the rudder to
neutral. Due to the rarity of such multiple reversals, the rule
specifies the new load condition is an ultimate load condition rather
than a limit load condition. Consequently, the applicant does not have
to apply an additional factor of safety to the calculated load
levels.\1\
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\1\ The terms ``limit,'' ``ultimate,'' and ``factor of safety''
are addressed in Sec. Sec. 25.301, 25.303, and 25.305. To
summarize, design loads are typically expressed in terms of limit
loads, which are then multiplied by a factor of safety, usually 1.5,
to determine ultimate loads. In this final rule, the design loads
are expressed as ultimate loads and no additional safety factor is
applied.
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This final rule affects manufacturers of transport category
airplanes applying for a new type certificate after the effective date
of the final rule. The rule may also affect applicants applying for an
amended or supplemental type certificate as determined under 14 CFR
21.101, ``Designation of applicable regulations,'' after the effective
date of the final rule.
The final rule will entail minimal cost, with expected net safety
benefits from the reduced risk of rudder reversal accidents.
II. Background
A. Statement of the Problem
The rudder is a vertical control surface on the tail of most
airplanes that helps the airplane to turn. Rudder control systems are
either powered or unpowered.\2\ Accident and incident data show pilots
sometimes make multiple and unnecessary rudder reversals during flight.
In addition, FAA-sponsored research \3\ indicates that pilots use the
rudder more often than previously expected and often in ways not
recommended by manufacturers. Section 25.1583(a)(3)(ii) requires
manufacturers to provide documentation that warns pilots against making
large and rapid control reversals, as they may result in
[[Page 71204]]
structural failures at any speed, including airspeeds below the design
maneuvering speed (VA). Despite the Sec. 25.1583(a)(3)(ii)
requirement, and that such rudder reversals are unnecessary and
discouraged by flightcrew training programs, these events continue to
occur.
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\2\ A powered rudder control surface is one in which the force
required to deflect the surface against the airstream is generated
or augmented by non-mechanical means, such as hydraulic or electric
systems. Powered rudder control systems include fly-by-wire and
hydro-mechanical systems. An unpowered rudder control surface is one
for which the force required to deflect the rudder control surface
is transmitted from the pilot's rudder pedal directly to the rudder
control surface through mechanical means. Unpowered rudder control
systems are also known as mechanical systems. Incorporation of a
powered yaw damper into an otherwise unpowered rudder control system
does not constitute a powered rudder control system. Other powered
systems, such as electrical, hydraulic, or pneumatic systems, may
aid in the reduction of pedal forces required for single engine-out
operations or to trim out pedal force to maintain a steady heading.
However, if such a powered systems does not contribute to hinge
moment generation (the twisting force on the rudder surface) during
maneuvering of a fully operational airplane, it is not a powered
rudder control system.
\3\ Report No. DOT/FAA/AM-10/14, ``An International Survey of
Transport Airplane Pilots' Experiences and Perspectives of Lateral/
Directional Control Events and Rudder Issues in Transport Airplanes
(Rudder Survey),'' dated October 2010, is available in the Docket
and at http://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/2010s/media/201014.pdf.
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Section 25.351 (``Yaw maneuver conditions''), which sets forth the
standard for protecting the airplane's vertical stabilizer from pilot-
commanded maneuver loads, only addresses a single, full rudder input at
airspeeds up to the design diving speed (VD).\4\ This design
standard does not protect the airplane from the loads imposed by
repeated inputs in opposing directions, or rudder reversals.\5\ If the
loads on the vertical stabilizer exceed those for which it is designed,
the vertical stabilizer may fail, resulting in the catastrophic loss of
airplane control.
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\4\ VD is the design diving speed: the maximum speed
at which the airplane is certified to fly. See 14 CFR 1.2 and
25.335.
\5\ A rudder ``reversal'' is a continuous, pilot-commanded
control movement starting from control displacement in one direction
followed by control displacement in the opposite direction.
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The primary example of this risk is the crash of American Airlines
Flight 587 (AA587), which occurred near Queens, New York, on November
12, 2001, and resulted in the death of all 260 passengers and crew
aboard and of five persons on the ground. The National Transportation
Safety Board (NTSB) found that the probable cause of the accident was
``the in-flight separation of the vertical stabilizer [airplane fin] as
a result of loads above ultimate design created by the first officer's
unnecessary and excessive rudder pedal inputs.'' \6\ The NTSB also
noted that contributing to these rudder pedal inputs were
characteristics of the Airbus A300-600 rudder system design and
elements of the American Airlines Advanced Aircraft Maneuvering
Program.
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\6\ NTSB Aircraft Accident Report NTSB/AAR-04/04, ``In-flight
Separation of Vertical Stabilizer, American Airlines Flight 587,
Airbus Industrie A300-605R, N14053, Belle Harbor, New York, November
12, 2001,'' dated October 26, 2004, https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0404.pdf, p. 160.
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Although the AA587 accident is the only catastrophic accident
resulting from rudder reversals, other notable accidents and incidents
involving airplanes that have a powered control ruder surface have
occurred.\7\ Ultimate loads were exceeded in two of the other notable
rudder reversal events: an incident involving Interflug (Moscow,
February 11, 1991) and an accident involving American Airlines Flight
903 (AA903) (near West Palm Beach, Florida, May 12, 1997).\8\ The
Interflug incident involved multiple rudder reversals, and loads of
1.55 and 1.35 times the limit load were recorded. For the AA903
incident, eight rudder reversals occurred, and a load of 1.53 times the
limit load was recorded.\9\ A catastrophe similar to AA587 was averted
in these two events only because the vertical stabilizers were stronger
than required by design standards.\10\ In another event, an incident
involving Air Canada Flight 190 (AC190) (over the state of Washington,
January 10, 2008), four rudder reversals occurred, and the limit load
was exceeded by 29 percent.\11\ Finally, in an incident involving
Provincial Airlines Limited (St. John's, Newfoundland and Labrador, May
27, 2005), the pilot commanded a pedal reversal during climb-out, when
the airplane entered an aerodynamic stall.\12\ The loads occurring
during this event were less than limit loads, but this incident is
additional evidence that pedal reversals occur in service.
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\7\ FAA Aviation Rulemaking Advisory Committee. Flight Controls
Harmonization Working Group. ``Rudder Pedal Sensitivity/Rudder
Reversal Recommendation Report,'' November 7, 2013. (ARAC Rudder
Reversal Report). This Report identifies four notable rudder events
to which the FAA adds the Interflug incident discussed in the NTSB
AA587 Report.
\8\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 106-109.
\9\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 104.
\10\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 38-39.
\11\ Transportation Safety Board of Canada (TSB) Aviation
Investigation Report A08W0007, ``Encounter with Wake Turbulence,''
https://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2008/A08W0007/A08W0007.html.
\12\ TSB Aviation Investigation Report A05A0059, ``Stall and
Loss of Control During Climb,'' https://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2005/a05a0059/a05a0059.html.
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In 2006, the FAA sponsored a survey \13\ to better comprehend
transport category pilots' understanding and use of the rudder. This
survey inquired of transport pilots from all over the world. The FAA's
analysis of the survey data found that--
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\13\ Report No. DOT/FAA/AM-10/14 (see footnote 3), OMB Control
No. 2120-0712.
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Pilots use the rudder more than FAA experts previously
thought and often in ways not recommended by manufacturers.
Pilots make erroneous rudder pedal inputs, some of which
include rudder reversals.
Even after specific training, many pilots are not aware
that they should not make rudder reversals, even below VA.
Over the last several years, training and changes to airplane flight
manuals directed the pilot to avoid making cyclic control inputs. The
rudder reversals that caused the AC190 incident in 2008 and the
Provincial Airlines Limited incident in 2005 occurred despite these
efforts.
Pilots in airplane upset situations (e.g., wake vortex encounters)
may revert to prior training and make sequential rudder reversals.
Based on information from the survey, the FAA expects that repeated
rudder reversals will continue to occur despite flightcrew training,
because training alone cannot address all potential flightcrew
behaviors that can lead to such inputs. For example, the relationship
between rudder inputs and the roll and yaw responses of the airplane
can become confusing to pilots. This is particularly true with the
large yaw and roll rates that result from large rudder inputs, combined
with naturally-occurring delays between pedal input and airplane
response that result from transport airplane flight dynamics. Such
confusion might lead pilots to command repeated rudder reversals.
B. National Transportation Safety Board (NTSB) Recommendation
Following the AA587 accident, the NTSB submitted safety
recommendations to the FAA. The NTSB stated, ``[f]or airplanes with
variable stop rudder travel limiter systems, protection from dangerous
structural loads resulting from sustained alternating large rudder
pedal inputs can be achieved by reducing the sensitivity of the rudder
control system (for example, by increasing the pedal forces), which
would make it harder for pilots to quickly perform alternating full
rudder inputs.'' \14\ In Safety Recommendation A-04-056,\15\ the NTSB
recommended the FAA modify part 25 to ``include a certification
standard that will ensure safe handling qualities in the yaw axis
throughout the flight envelope, including limits for rudder pedal
sensitivity.'' This final rule addresses this recommendation and will
reduce the likelihood of an event that would be similar to the AA587
accident.
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\14\ NTSB Safety Recommendation, November 10, 2004, at p. 2.
This document is available in the docket and at http://www.ntsb.gov/safety/safety-recs/RecLetters/A04_56_62.pdf.
\15\ NTSB Safety Recommendation A-04-056, dated November 10,
2004, is available in the docket and at http://www.ntsb.gov/safety/safety-recs/RecLetters/A04_56_62.pdf.
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C. Aviation Rulemaking Advisory Committee (ARAC) Activity
In 2011, the FAA tasked the ARAC to consider the need to add a new
flight maneuver load condition to part 25, subpart C, that would
``ensure airplane structural capability in the presence of
[[Page 71205]]
rudder reversals'' and increasing sideslip angles (yaw angles) at
airspeeds up to VD. The FAA also tasked the ARAC to consider
whether other airworthiness standards would address this concern, such
as pedal characteristics that would discourage pilots from making
rudder reversals.\16\ The ARAC delegated this task to the Transport
Airplane and Engine subcommittee, which assigned it to the Flight
Controls Harmonization Working Group (FCHWG) of the subcommittee.
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\16\ The FAA published this notice of ARAC tasking in the
Federal Register on March 28, 2011. Aviation Rulemaking Advisory
Committee; Transport Airplane and Engine Issues--New Task, 76 FR
17183.
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The ARAC FCHWG completed its report in November 2013.\17\ ARAC
approved the report and submitted it to the FAA on December 30, 2013.
One of the recommendations of the ARAC FCHWG Rudder Reversal Report was
to require transport category airplanes to be able to withstand safely
the loads imposed by three rudder reversals.\18\ This final rule adopts
that recommendation. The ARAC report indicates that requiring transport
category airplanes to operate safely with the vertical stabilizer loads
imposed by three full-pedal reversals accounts for most of the
attainable safety benefits. With more than three rudder reversals, the
ARAC FCHWG found little increase in vertical stabilizer loads.
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\17\ ARAC FCHWG Recommendation Report, ``Rudder Pedal
Sensitivity/Rudder Reversal,'' dated November 7, 2013, is available
in the Docket and at https://www.faa.gov/regulations_policies/rulemaking/committees/documents/media/TAEfch-rpsrr-3282011.pdf.
\18\ One member of the ARAC FCHWG did not support any
rulemaking. The remaining members of the ARAC FCHWG found that a yaw
maneuver load condition would be the optimal way to protect the
airplane from the excessive loads that can result from multiple
rudder reversals because they found systems solutions, such as fly-
by-wire systems and manual systems with appropriate yaw dampers, to
be too design-prescriptive. The members of the ARAC FCHWG held
divided opinions, however, on what the load condition should be.
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The report's findings and recommendations guided the formation of
the FAA's Yaw Maneuver Conditions--Rudder Reversals notice of proposed
rulemaking (NPRM) (83 FR 32087, July 16, 2018) and this final rule.
D. Summary of the NPRM
On July 16, 2018, the FAA published an NPRM that proposed to add a
new regulation to address rudder reversal conditions on transport
category airplanes (83 FR 32087). The FAA intended that this new
requirement would prevent structural failure of the rudder and vertical
stabilizer caused by reversals of the rudder pedals. Thus, the FAA
proposed to require that airplanes be able to withstand the structural
loads caused by three full reversals (doublets) of the rudder pedals.
The FAA proposed to apply the requirement only to airplanes with
powered rudder control surfaces.
E. Rulemaking by the European Union Aviation Safety Agency (EASA)
On November 5, 2018, EASA published amendment 22 to Certification
Specifications 25 (CS-25). This amendment included a new regulation, CS
25.353, ``Rudder control reversal conditions,'' as well as Acceptable
Means of Compliance 25.353. EASA's new regulation is similar to this
final rule except that the final rule adopted by the FAA applies only
to airplanes that have a powered rudder control surface or surfaces.
F. Advisory Material
FAA Advisory Circular (AC) 25.353-1, ``Rudder Control Reversal
Conditions,'' which accompanies this rule, provides guidance on
acceptable means, but not the only means, of showing compliance with
Sec. 25.353. AC 25.353-1 is available in the public docket for this
rulemaking.
III. Discussion of Public Comments and Final Rule
The FAA received comments from the NTSB, Airline Pilots
Association, International (ALPA), ATR, Crew Systems, Textron Aviation,
Airbus, The Boeing Company, and Bombardier Aerospace. The NTSB, ALPA,
ATR, and Crew Systems supported the proposal and did not suggest
changes to it. Textron Aviation and Airbus requested that the rule
specify a single, full-pedal command followed by one rudder reversal
and return to neutral, rather than three rudder reversals as proposed
in the NPRM. Those two companies, along with Boeing, also requested
other changes, as described in this section of the preamble. Bombardier
Aerospace commented on the rule's cost, suggesting that the FAA issue
guidance to limit the rule's applicability.
A. Necessity of Three Reversals
In the NPRM, the FAA proposed a design load condition that consists
of a single, full-pedal command followed by three full-pedal reversals
and return to neutral. Two airplane manufacturers, Textron Aviation and
Airbus, requested that the rule instead specify a single, full-pedal
command followed by one rudder reversal and return to neutral. These
companies believed this condition was more appropriate given the rarity
of rudder reversals and the uniqueness of the AA587 accident airplane.
They advocated that a single, full-pedal command followed by one rudder
reversal and return to neutral would cover all other known incidents,
stated their concern that the proposed criteria could result in weight
penalties or detrimental system changes, and proposed that enhanced
flightcrew training would be more effective than designing for multiple
rudder reversals.
The FAA emphasizes that while rudder reversals are rare, they can
lead to serious consequences. The AA587 accident and four other
accidents and incidents involved multiple rudder reversals, some of
which were full-pedal reversals. Since these accidents occurred, modern
airplane design requirements have not changed in a manner that would
deter pilots from making such multiple reversals. Additionally, based
on information received in response to the 2006 pilot survey, the FAA
found that some respondents reported making rudder pedal reversals
(cyclic rudder-pedal commands).\19\ Moreover, an analysis in the ARAC
report shows that loads would continue to increase upon subsequent
pedal reversals. Therefore, a single, full-pedal command followed by
one full-pedal reversal and return to neutral would not represent the
conditions resulting from multiple full-pedal reversals that may result
in injuries to occupants or a structural failure that jeopardizes
continued safe flight and landing of the airplane. Data from all
manufacturers on the ARAC FCHWG showed that after three full-pedal
reversals, the maximum sideslip angle does not increase significantly.
Maximum sideslip angle causes the maximum loads on the vertical
stabilizer; therefore, three full-pedal reversals result in a load
condition that accounts for most of the attainable safety benefits.
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\19\ Report No. DOT/FAA/AM-10/14 at p. 14 (see footnote 3).
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Regarding the concern that the proposed multiple reversal condition
could result in potential weight penalties or detrimental system
changes in future designs, as discussed in the NPRM preamble, the FAA
expects that most applicants will use control laws to comply with this
rule. Because manufacturers typically implement control laws through
systems and software, use of this solution to comply would result in
little to no incremental cost in the form of weight, equipment,
maintenance, or training for those airplanes with powered rudder
control surfaces.
Based on information from the 2006 survey, the FAA does not agree
with
[[Page 71206]]
Textron and Airbus that enhanced flight crew training would be more
effective than designing for multiple full-pedal reversals. As
described earlier in the preamble, the FAA's analysis of the survey
found that even after specific training, many pilots are not aware that
they should not make full-pedal reversals, even below VA.
While training and changes to airplane flight manuals directed the
pilot to avoid making cyclic control inputs, the pedal reversals that
caused the AC190 incident in 2008 and the Provincial Airlines Limited
incident in 2005 occurred despite these efforts.
Moreover, in transport category airplanes, rudder inputs are
generally limited to aligning the airplane with the runway during
crosswind landings and controlling engine-out situations, which occur
predominately at low speeds. At high speeds, the pilot normally
directly rolls the airplane using the ailerons.\20\ If the pilot does
use the rudder to control the airplane at high speeds, there will be a
significant phase lag between the rudder input and the roll response
because the roll response is a secondary effect of the yawing moment
generated by the rudder.\21\ The roll does not result from the rudder
input directly. Even if the rudder is subsequently deflected in the
opposite direction (rudder reversal), the airplane can continue to roll
and yaw in one direction before reversing because of the phase lag. The
relationship between rudder inputs and the roll and yaw response of the
airplane can become confusing to pilots, particularly with the large
yaw and roll rates that would result from large rudder inputs, causing
the pilots to input multiple rudder reversals.
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\20\ An aileron is a hinged control service on the trailing edge
of the wing of a fixed-wing aircraft, one aileron per wing.
\21\ The yaw axis is defined to be perpendicular to the wings
and to the normal line of flight. A yaw movement is a change in the
direction of the aircraft to the left or right around the yaw axis.
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For the foregoing reasons, the FAA has determined that a three
full-pedal reversal condition is necessary to account for the effects
of multiple rudder reversals that the FAA expects to occur in service.
The FAA adopts this aspect of the proposal without change.
B. Applicability
Airbus requested that the rule apply only to new aircraft designs;
Bombardier requested that the rule apply only to new airplanes or to
airplanes where the rudder system has been significantly modified. The
FAA agrees in part with the comments regarding applicability. This
final rule requires that new airplane designs meet the new standards.
Where an applicant proposes a change to a previously approved type
design, Sec. 21.101, ``Designation of applicable regulations,''
requires an assessment to determine the amendment level (version) of
each regulation to be applied to that type design change. The FAA would
determine under the provisions of Sec. 21.101 whether this final rule
would be applied to a changed airplane design.
Additionally, Airbus requested that the rule apply to all transport
category airplanes, including those with unpowered control surfaces.
Similarly, the corresponding and recently adopted European Union
Aviation Safety Agency (EASA) rule, CS 25.353, applies to all
airplanes, including those with unpowered control surfaces. However, in
the NPRM, the FAA proposed to apply this rule only to airplanes with a
powered control surface or surfaces.
A powered rudder control surface is one in which the force required
to deflect the surface against the airstream is generated or augmented
by hydraulic or electric systems. In contrast, an unpowered rudder
control surface is one for which the force required to deflect the
surface against the airstream is transmitted from the pilot's rudder
pedal directly through mechanical means, without any augmentation from
hydraulic or electrical systems. Powered rudder control systems include
fly-by-wire (FBW) and hydro-mechanical systems, while unpowered rudder
control systems are also known as mechanical systems. Incorporation of
a powered yaw damper into an otherwise unpowered rudder control system
does not constitute a powered rudder control surface, for the purpose
of this rule.
Small business jets that typically have unpowered rudder control
surfaces provide immediate feedback to their flightcrews in response to
yaw inputs. Those flightcrews are, therefore, less likely to execute
inappropriate rudder pedal reversals. The FAA reviewed accident and
incident records and found no events in which pilots commanded
inappropriate full-pedal reversals on airplanes with unpowered rudder
control surfaces. Also, the use of airplanes with unpowered rudder
control surfaces is diminishing in the transport category fleet. The
only transport category airplane model in U.S. production with an
unpowered rudder control surface also has a yaw damper. The normal
operation of the yaw damper would be adequate to reduce yaw overshoot
loads from full-pedal reversals.
As explained in the NPRM and this final rule, the safety benefit of
expanding this rule to airplanes with unpowered control surfaces does
not outweigh the potentially higher costs of implementation. The FAA
may consider the requested change later if data or information become
available to indicate that either the safety case has changed or
implementation costs have decreased.
C. Load Condition Requirements
Airbus and Boeing requested the FAA include in the rule the
following text: ``Flaps (or flaperons or any other aerodynamic devices
when used as flaps) and slats extended configurations are also to be
considered if they are used in en route conditions.'' Including this
provision would require applicants to evaluate the rudder reversal
conditions with flaps and other devices extended, if the airplane uses
those devices in en route conditions.\22\ Airbus also requested that
the rule include the following text: ``Unbalanced aerodynamic moments
about the center of gravity must be reacted in a rational or
conservative manner considering the airplane inertia forces.'' This
language specifies how the applicant sums the various forces when
analyzing the rudder reversal conditions. Both commenters requested the
FAA include these requirements in the final rule to be consistent with
the ARAC FCHWG report and to harmonize with the EASA regulation.
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\22\ En route conditions means the conditions occurring during
any phase of flight after initial climb and before the final descent
and landing phase.
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The FAA agrees that the additions identified by commenters should
be included in the final rule because both requirements harmonize with
the EASA rule (CS 25.353) and clarify how to analyze the load
conditions. The two requirements are also found in other part 25
regulations, including Sec. Sec. 25.345 and 25.351. The FAA notes that
the requirement to consider the effect of flaps and slats in en route
conditions has slightly different wording than the EASA rule, but has
the same meaning. As these changes simply clarify how to analyze the
load conditions, they will not add additional burdens.
Airbus also requested that the airplane be able to withstand the
prescribed conditions at an uppermost speed of VC, rather
than VC/MC, as proposed in the NPRM. The FAA
disagrees with the commenter. The proposed rule included VC/
MC because airplanes have defined limitations for both
VC and MC. However, no substantive difference
between the two exists because each value of VC has a
corresponding value of MC. As a result, using VC/
MC is appropriate in this rule.
[[Page 71207]]
D. Warning Monitors
Airbus requested that the rule allow an applicant to show
compliance via implementing monitors that would warn the pilot of
inappropriate rudder use. The FAA does not agree with this comment.
Pilot-commanded rudder reversals have occurred during high workload and
conditions that are often startling. Thus, depending on the pilot to
react appropriately to a warning under such conditions would not
provide the equivalent safety benefit as the load conditions in this
final rule and would be inconsistent with the EASA regulation.
E. Miscellaneous Modifications
As previously noted, EASA published its regulation, CS 25.353, on
November 5, 2018, a few months after the FAA issued the NPRM upon which
this final rule is based. This final rule contains minor modifications
to harmonize with the EASA standard. These modifications are in
addition to those described earlier in the final rule (C. Load
Condition Requirements). These modifications include:
(1) The proposed rule specified that the applicant evaluate the
rudder reversal conditions ``from VMC or the highest
airspeed for which it is possible to achieve maximum rudder deflection
at zero sideslip, whichever is greater, up to VC/
MC.'' This final rule establishes the speed range as
``VMC to VC/MC.'' This is simpler to
apply because it does not require an additional calculation of ``the
highest speed for which it is possible . . .'' and it is consistent
with the current rudder maneuver condition required by Sec. 25.351.
(Section 25.351 prescribes the speed range as VMC to
VD.)
(2) This final rule provides that any permanent deformation
resulting from the specified ultimate load conditions must not prevent
continued safe flight and landing. This requirement is necessary
because this final rule, unlike most design load conditions codified in
part 25, contains only an ``ultimate'' load requirement, and does not
contain a ``limit'' load requirement. Design loads are typically
expressed in terms of limit loads, which are then multiplied by a
factor of safety, usually 1.5, to determine ultimate loads. The
airplane structure must be able to withstand limit loads without
detrimental permanent deformation and ultimate loads without failure in
accordance with Sec. 25.305. Because this rule does not include a
limit load requirement, it is necessary to require that no detrimental
permanent deformation occur at ultimate load (deformation that would
prevent continued safe flight and landing). This requirement is also in
the corresponding EASA regulation, CS 25.353.
(3) The proposed rule specified that the ``rudder control is
suddenly displaced'' in evaluating the ultimate loads that result from
the yaw maneuver conditions identified in the proposal. This final
rule, however, specifies that the ``rudder control is suddenly and
fully displaced as limited by the control system or control surface
stops.'' The term ``fully'' makes it clear that full displacement of
the rudder pedal is required. The phrase ``as limited by the control
system or control surface stops'' further clarifies the requirement by
indicating that the conditions may be conducted using rudder control
system limiting hardware to establish the reversal loads. Furthermore,
the aforementioned requirements are consistent with Sec. 25.351.
IV. Regulatory Notices and Analyses
Changes to Federal regulations must undergo several economic
analyses. First, Executive Orders 12866 and 13563 direct that each
Federal agency shall propose or adopt a regulation only upon a reasoned
determination that the benefits of the intended regulation justify its
costs. Second, the Regulatory Flexibility Act of 1980 (Pub. L. 96-354),
as codified in 5 U.S.C. 603 et seq., requires agencies to analyze the
economic impact of regulatory changes on small entities. Third, the
Trade Agreements Act of 1979 (Pub. L. 96-39), 19 U.S.C. Chapter 13,
prohibits agencies from setting standards that create unnecessary
obstacles to the foreign commerce of the United States. In developing
U.S. standards, the Trade Agreements Act requires agencies to consider
international standards and, where appropriate, that they be the basis
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995
(Pub. L. 104-4), as codified in 2 U.S.C. Chapter 25, requires agencies
to prepare a written assessment of the costs, benefits, and other
effects of proposed or final rules that include a Federal mandate
likely to result in the expenditure by State, local, or tribal
governments, in the aggregate, or by the private sector, of $100
million or more annually (adjusted for inflation with base year of
1995). This portion of the preamble summarizes the FAA's analysis of
the economic impacts of this final rule.
In conducting these analyses, the FAA has determined that this
final rule has benefits that justify its costs and is not a
``significant regulatory action'' as defined in section 3(f) of
Executive Order 12866. The final rule is also not ``significant'' as
defined in DOT's rulemaking procedures. The final rule will not have a
significant economic impact on a substantial number of small entities,
will not create unnecessary obstacles to the foreign commerce of the
United States, and will not impose an unfunded mandate on State, local,
or tribal governments, or on the private sector by exceeding the
threshold identified previously.
A. Regulatory Evaluation
1. Background and Statement of Need
The genesis of this final rule is the crash of American Airlines
Flight 587 (AA587), near Queens, New York, on November 12, 2001,
resulting in the death of all 260 passengers and crew aboard, and the
death of five persons on the ground. The airplane was destroyed by
impact forces and a post-crash fire.
The NTSB found that the probable cause of the accident was ``the
in-flight separation of the vertical stabilizer [airplane fin] as a
result of loads above ultimate design created by the first officer's
unnecessary and excessive rudder pedal inputs.'' \23\ Ultimate loads on
the airplane structure are the limit loads (1.0) multiplied by a safety
factor, usually 1.5 (as for the vertical stabilizer). An airplane is
expected to experience a limit load once in its lifetime and is never
expected to experience an ultimate load.\24\ For the AA587 accident,
loads exceeding ultimate loads ranged from 1.83 to 2.14 times the limit
load on the vertical stabilizer,\25\ as a result of four, full,
alternating rudder inputs known as ``rudder reversals.''
---------------------------------------------------------------------------
\23\ NTSB Aircraft Accident Report NTSB/AAR-04/04, ``In-flight
Separation of Vertical Stabilizer, American Airlines Flight 587,
Airbus Industrie A300-605R, N14053, Belle Harbor, New York, November
12, 2001'' at 160 (Oct. 26, 2004), available at https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0404.pdf.
\24\ NTSB Aircraft Accident Report NTSB/AAR-04/04, p. 31, n. 53.
\25\ NTSB Aircraft Accident Report NTSB/AAR-04/04, p. 104.
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Significant rudder reversal events are unusual in the history of
commercial airplane flight, having occurred during five notable
accidents and incidents, with the AA587 accident being the only
catastrophic accident resulting from rudder reversals.\26\ Ultimate
loads were exceeded in two of the other notable rudder reversal events:
an incident involving Interflug (Moscow, February
[[Page 71208]]
11, 1991) and an accident involving American Airlines Flight 903
(AA903) (near West Palm Beach, Florida, May 12, 1997).\27\ The
Interflug incident involved multiple rudder reversals, and loads of
1.55 and 1.35 times the limit load were recorded. For the AA903
incident, eight rudder reversals occurred, and a load of 1.53 times the
limit load was recorded.\28\ A catastrophe similar to AA587 was averted
in these two events only because the vertical stabilizers were stronger
than required by design standards.\29\ In a fourth event--Air Canada
Flight 190 (AC190) (over the state of Washington, January 10, 2008)--
four rudder reversals occurred, and the limit load was exceeded by 29
percent.\30\ The fifth event was a de Havilland DHC-8-100 (Dash 8) (St.
John's, Newfoundland and Labrador, May 27, 2005) in which the pilot
commanded a pedal reversal during climb-out, when the airplane entered
an aerodynamic stall.\31\ There were no injuries, and the airplane was
not damaged. The ARAC FCHWG determined the loads occurring during this
event were less than limit load, but this incident is additional
evidence that pedal reversals occur in service.
---------------------------------------------------------------------------
\26\ FAA Aviation Rulemaking Advisory Committee. Flight Controls
Harmonization Working Group. ``Rudder Pedal Sensitivity/Rudder
Reversal Recommendation Report,'' November 7, 2013. (ARAC Rudder
Reversal Report). This Report identifies four notable rudder events
to which the FAA adds the Interflug incident discussed in the NTSB
AA587 Report.
\27\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 106-109;
see also NTSB Aircraft Accident Report AA903 (NTSB DCA97MA049).
\28\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 104;
Report on the Investigation of the Abnormal Behavior of an Airbus
A310-304 Aircraft on 11.02.199 at Moscow, Air Accident Investigation
Department of the German Federal Office of Aviation, Reference
6X002-0/91.
\29\ NTSB Aircraft Accident Report NTSB/AAR-04/04, pp. 38-39.
\30\ Transportation Safety Board of Canada (TSB) Aviation
Investigation Report A08W0007, ``Encounter with Wake Turbulence,''
https://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2008/08W0007/A08W0007.html.
\31\ TSB Aviation Investigation Report A05A0059, ``Stall and
Loss of Control During Climb,'' https://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2005/a05a0059/a05a0059.html.
---------------------------------------------------------------------------
In transport category airplanes, rudder inputs are generally
limited to aligning the airplane with the runway during crosswind
landings and controlling engine-out situations, which occur
predominately at low speeds. At high speeds, the pilot normally
directly rolls the airplane using the ailerons.\32\ If the pilot does
use the rudder to control the airplane at high speeds, there will be a
significant phase lag between the rudder input and the roll response
because the roll response is a secondary effect of the yawing moment
generated by the rudder.\33\ The roll does not result from the rudder
input directly. Even if the rudder is subsequently deflected in the
opposite direction (rudder reversal), the airplane can continue to roll
and yaw in one direction before reversing because of the phase lag. The
relationship between rudder inputs and the roll and yaw response of the
airplane can become confusing to pilots, particularly with the large
yaw and roll rates that would result from large rudder inputs, causing
the pilots to input multiple rudder reversals.
---------------------------------------------------------------------------
\32\ An aileron is a hinged control service on the trailing edge
of the wing of a fixed-wing aircraft, one aileron per wing.
\33\ The yaw axis is defined to be perpendicular to the wings
and to the normal line of flight. A yaw movement is a change in the
direction of the aircraft to the left or right around the yaw axis.
---------------------------------------------------------------------------
Following the AA587 accident in November 2004, the NTSB issued
Safety Recommendation A-04-56, recommending that the FAA modify part 25
``to include a certification standard that will ensure safe handling
qualities in the yaw axis throughout the flight envelope . . . .'' \34\
In 2011, the FAA tasked ARAC to consider the need for rulemaking to
address the rudder reversal issue. ARAC delegated this task to the
Transport Airplane and Engine subcommittee, which assigned it to the
FCHWG. One of the recommendations of the ARAC FCHWG Rudder Reversal
Report, issued on November 7, 2013, was to require transport category
airplanes to be able to withstand safely the loads imposed by three
rudder reversals. This final rule adopts that recommendation. The ARAC
report indicates that requiring transport category airplanes to operate
safely with the vertical stabilizer loads imposed by three full-pedal
reversals accounts for most of the attainable safety benefits. With
more than three rudder reversals, the FCHWG found little increase in
vertical stabilizer loads.
---------------------------------------------------------------------------
\34\ NTSB Safety Recommendation A-04-56 (Nov. 10, 2004),
available at https://www.ntsb.gov/safety/safety-recs/RecLetters/A04_56_62.pdf.
---------------------------------------------------------------------------
2. Impacts of This Final Rule
Since the catastrophic AA587 accident, the FAA has requested that
applicants for new type certificates show that their designs are
capable of continued safe flight and landing after experiencing
repeated rudder reversals. For airplanes with fly-by-wire (FBW)
systems, manufacturers have been able to show capability by means of
control laws, incorporated through software changes, adding no weight
and imposing no additional maintenance cost to the airplanes. Many, if
not all, of these designs have demonstrated tolerance to three or more
rudder reversals. Aside from converting to an FBW or hydro-mechanical
system, alternatives available to manufacturers specializing in
airplane designs with mechanical rudders include increasing the
reliability of the yaw damper and strengthening the airplane vertical
stabilizer.
To estimate the cost of the final rule, the FAA reviewed unit cost
estimates from U.S. airplane manufacturers and incorporated these
estimates into an airplane life cycle model. The FAA received one
estimate for large part 25 airplanes and two estimates for small part
25 airplanes (i.e., business jets).
A manufacturer specializing in mechanical rather than FBW rudder
systems provided a business jet estimate that reflects significantly
higher compliance costs. This manufacturer's most cost-efficient
approach to addressing the requirement--although high in comparison to
manufacturers that use FBW systems exclusively--is to comply with a
strengthened vertical stabilizer. The cost of complying with a more
reliable yaw damper was higher than strengthening the vertical
stabilizer, and higher still if complying by converting to an FBW
rudder system for new models.
As a result of these high costs and the reasons set forth in the
NPRM and the preceding ``Discussion of Comments and Final Rule,'' this
final rule will not apply to airplanes with unpowered (mechanical)
rudder control surfaces. An unpowered rudder control surface is one
whose movement is affected through mechanical means, without any
augmentation (for example, from hydraulic or electrical systems).
Accordingly, the final rule does not apply to models with mechanical
rudder control systems, but applies only to models with FBW or hydro-
mechanical rudder systems.
The FAA estimates the costs of the final rule using unit cost per
model estimates from industry for FBW models and the agency's estimates
of the number of new large airplane and business jet certifications
with FBW rudder systems in the ten years after the effective date of
the final rule. These estimates are shown in Table 1.
[[Page 71209]]
Table 1--Cost Estimated for Final Rule ($ 2016)
----------------------------------------------------------------------------------------------------------------
Number of new
Cost per model FBW models Costs
(10 yrs)
----------------------------------------------------------------------------------------------------------------
Large Airplanes................................................. $300,000 2 $600,000
Business Jets................................................... 235,000 2 470,000
-----------------------------------------------
Total Costs................................................. .............. .............. 1,070,000
----------------------------------------------------------------------------------------------------------------
With these cost estimates, the FAA concludes the final rule will
entail minimal cost, with expected net safety benefits from the reduced
risk of rudder reversal accidents.
B. Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA)
establishes ``as a principle of regulatory issuance that agencies shall
endeavor, consistent with the objectives of the rule and of applicable
statutes, to fit regulatory and informational requirements to the scale
of the businesses, organizations, and governmental jurisdictions
subject to regulation. To achieve this principle, agencies are required
to solicit and consider flexible regulatory proposals and to explain
the rationale for their actions to assure that such proposals are given
serious consideration.'' The RFA covers a wide range of small entities,
including small businesses, not-for-profit organizations, and small
governmental jurisdictions.
Agencies must perform a review to determine whether a rule will
have a significant economic impact on a substantial number of small
entities. If the agency determines that it will, the agency must
prepare a regulatory flexibility analysis as described in the RFA.
However, if an agency determines that a rule is not expected to have a
significant economic impact on a substantial number of small entities,
section 605(b) of the RFA provides that the head of the agency may so
certify and a regulatory flexibility analysis is not required. The
certification must include a statement providing the factual basis for
this determination, and the reasoning should be clear.
As noted above, because manufacturers with FBW rudder systems have
been able to show compliance by means of low-cost changes to control
laws incorporated through software changes, the FAA estimates the costs
of this final rule to be minimal. Therefore, pursuant to section
605(b), the head of the FAA certifies that this final rule will not
have a significant economic impact on a substantial number of small
entities.
C. International Trade Impact Assessment
The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal
agencies from establishing standards or engaging in related activities
that create unnecessary obstacles to the foreign commerce of the United
States. Pursuant to this Act, the establishment of standards is not
considered an unnecessary obstacle to the foreign commerce of the
United States, so long as the standard has a legitimate domestic
objective, such as the protection of safety, and does not operate in a
manner that excludes imports that meet this objective. The statute also
requires consideration of international standards and, where
appropriate, that they be the basis for U.S. standards.
The FAA has assessed the effect of this final rule and determined
that its purpose is to protect the safety of U.S. civil aviation.
Therefore, the final rule is in compliance with the Trade Agreements
Act.
D. Unfunded Mandates Assessment
Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement
assessing the effects of any Federal mandate in a proposed or final
agency rule that may result in an expenditure of $100 million or more
(in 1995 dollars) in any one year by State, local, and tribal
governments, in the aggregate, or by the private sector; such a mandate
is deemed to be a ``significant regulatory action.'' The FAA currently
uses an inflation-adjusted value of $155.0 million in lieu of $100
million.
This final rule does not contain such a mandate. Therefore, the
requirements of Title II of the Act do not apply.
E. Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. The FAA has determined that
there is no new requirement for information collection associated with
this final rule.
F. International Compatibility
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to conform to
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that correspond to these regulations.
G. Environmental Analysis
FAA Order 1050.1F, Environmental Impacts: Policies and Procedures,
identifies FAA actions that are categorically excluded from preparation
of an environmental assessment or environmental impact statement under
the National Environmental Policy Act in the absence of extraordinary
circumstances. The FAA has determined this rulemaking action qualifies
for the categorical exclusion identified in paragraph 5-6.6 for
regulations and involves no extraordinary circumstances.
V. Executive Order Determinations
A. Executive Order 13132, Federalism
The FAA has analyzed this final rule under the principles and
criteria of Executive Order 13132, Federalism. The agency determined
that this action will not have a substantial direct effect on the
States, or the relationship between the Federal Government and the
States, or on the distribution of power and responsibilities among the
various levels of government, and, therefore, does not have Federalism
implications.
B. Executive Order 13211, Regulations that Significantly Affect Energy
Supply, Distribution, or Use
The FAA analyzed this final rule under Executive Order 13211,
Actions Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). The agency has determined that it
is not a ``significant energy action'' under the executive order and it
is not likely to
[[Page 71210]]
have a significant adverse effect on the supply, distribution, or use
of energy.
C. Executive Order 13609, International Cooperation
Executive Order 13609, Promoting International Regulatory
Cooperation, (77 FR 26413, May 4, 2012) promotes international
regulatory cooperation to meet shared challenges involving health,
safety, labor, security, environmental, and other issues and reduce,
eliminate, or prevent unnecessary differences in regulatory
requirements. The FAA has analyzed this action under the policy and
agency responsibilities of Executive Order 13609. The agency has
determined that this action would eliminate differences between U.S.
aviation standards and those of other civil aviation authorities by
harmonizing with the corresponding EASA requirement. As noted above,
EASA published its corresponding regulation, CS 25.353, on November 5,
2018. This final rule harmonizes with that standard, with the exception
that this rule excludes airplanes that have an unpowered rudder control
surface(s).
VI. How to Obtain Additional Information
A. Rulemaking Documents
An electronic copy of a rulemaking document may be obtained by
using the internet--
1. Search the Federal eRulemaking Portal (http://www.regulations.gov);
2. Visit the FAA's Regulations and Policies web page at http://www.faa.gov/regulations_policies/; or
3. Access the Government Printing Office's web page at http://www.gpo.gov/fdsys/.
Copies may also be obtained by sending a request (identified by
notice, amendment, or docket number of this rulemaking) to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW, Washington, DC 20591, or by calling (202) 267-9680.
B. Comments Submitted to the Docket
Comments received may be viewed by going to http://www.regulations.gov and following the online instructions to search the
docket number for this action. Anyone is able to search the electronic
form of all comments received into any of the FAA's dockets by the name
of the individual submitting the comment (or signing the comment, if
submitted on behalf of an association, business, labor union, etc.).
C. Small Business Regulatory Enforcement Fairness Act
The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996 (Pub. L. 104-121) (set forth as a note to 5 U.S.C. 601) requires
the FAA to comply with small entity requests for information or advice
about compliance with statutes and regulations within its jurisdiction.
A small entity with questions regarding this document may contact its
local FAA official or the person listed under the FOR FURTHER
INFORMATION CONTACT heading at the beginning of the preamble. To find
out more about SBREFA on the internet, visit http://www.faa.gov/regulations_policies/rulemaking/sbre_act/.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends chapter I of title 14, Code of Federal
Regulations as follows:
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
0
1. The authority citation for part 25 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702 and
44704.
0
2. Add Sec. 25.353 under the undesignated center heading ``Flight
Maneuver and Gust Conditions'' to read as follows:
Sec. 25.353 Rudder control reversal conditions.
Airplanes with a powered rudder control surface or surfaces must be
designed for loads, considered to be ultimate, resulting from the yaw
maneuver conditions specified in paragraphs (a) through (e) of this
section at speeds from VMC to VC/MC.
Any permanent deformation resulting from these ultimate load conditions
must not prevent continued safe flight and landing. The applicant must
evaluate these conditions with the landing gear retracted and speed
brakes (and spoilers when used as speed brakes) retracted. The
applicant must evaluate the effects of flaps, flaperons, or any other
aerodynamic devices when used as flaps, and slats-extended
configurations, if they are used in en route conditions. Unbalanced
aerodynamic moments about the center of gravity must be reacted in a
rational or conservative manner considering the airplane inertia
forces. In computing the loads on the airplane, the yawing velocity may
be assumed to be zero. The applicant must assume a pilot force of 200
pounds when evaluating each of the following conditions:
(a) With the airplane in unaccelerated flight at zero yaw, the
flightdeck rudder control is suddenly and fully displaced to achieve
the resulting rudder deflection, as limited by the control system or
the control surface stops.
(b) With the airplane yawed to the overswing sideslip angle, the
flightdeck rudder control is suddenly and fully displaced in the
opposite direction, as limited by the control system or control surface
stops.
(c) With the airplane yawed to the opposite overswing sideslip
angle, the flightdeck rudder control is suddenly and fully displaced in
the opposite direction, as limited by the control system or control
surface stops.
(d) With the airplane yawed to the subsequent overswing sideslip
angle, the flightdeck rudder control is suddenly and fully displaced in
the opposite direction, as limited by the control system or control
surface stops.
(e) With the airplane yawed to the opposite overswing sideslip
angle, the flightdeck rudder control is suddenly returned to neutral.
Issued under authority provided by 49 U.S.C. 106(f), and
44701(a) in Washington, DC, on or about November 16, 2022.
Billy Nolen,
Acting Administrator.
[FR Doc. 2022-25291 Filed 11-21-22; 8:45 am]
BILLING CODE 4910-13-P