Special Conditions: The Boeing Company Model 787-10 Airplane; Aeroelastic Stability Requirements, Flaps-Up Vertical Modal-Suppression System, 64360-64364 [2016-22547]
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Federal Register / Vol. 81, No. 182 / Tuesday, September 20, 2016 / Proposed Rules
the Director, when promulgating
regulations relating to the Banks, to
consider the differences between Fannie
Mae and Freddie Mac (collectively, the
Enterprises) and the Banks with respect
to: the Banks’ cooperative ownership
structure; mission of providing liquidity
to members; affordable housing and
community development mission;
capital structure; joint and several
liability; and any other differences the
Director considers appropriate. See 12
U.S.C. 4513(f). In preparing this 2016
proposed rulemaking, the Director
considered the differences between the
Banks and the Enterprises as they relate
to the above factors, and determined
that the Banks should not be treated
differently from the Enterprises for
purposes of this 2016 proposed
rulemaking. Any regulated entity in
conservatorship (or receivership or a
limited-life regulated entity), whether a
Bank or an Enterprise, would be outside
the scope of the proposed rule.
sradovich on DSK3GMQ082PROD with PROPOSALS
V. Paperwork Reduction Act
This proposed rulemaking does not
contain any information collection
requirement that requires the approval
of the Office of Management and Budget
(OMB) under the Paperwork Reduction
Act (44 U.S.C. 3501 et seq.). Therefore,
FHFA has not submitted any
information to OMB for review.
VI. Regulatory Flexibility Act
The Regulatory Flexibility Act (5
U.S.C. 601 et seq.) requires that a
regulation that has a significant
economic impact on a substantial
number of small entities, small
businesses, or small organizations must
include an initial regulatory flexibility
analysis describing the regulation’s
impact on small entities. Such an
analysis need not be undertaken if the
agency has certified that the regulation
will not have a significant economic
impact on a substantial number of small
entities. 5 U.S.C. 605(b). FHFA has
considered the impact of the 2016
proposed rulemaking under the
Regulatory Flexibility Act. The General
Counsel of FHFA certifies that this 2016
proposed rulemaking, if adopted as a
final rule, is not likely to have a
significant economic impact on a
substantial number of small entities
because it would apply primarily to the
regulated entities and the OF, which are
not small entities for purposes of the
Regulatory Flexibility Act.
List of Subjects in 12 CFR Part 1231
Indemnification payments,
Government-sponsored enterprises.
Accordingly, for reasons stated in the
preamble, under the authority of 12
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U.S.C. 4518(e) and 4526, FHFA
proposes to amend part 1231 of
subchapter B of chapter XII of title 12
of the CFR as follows:
PART 1231—GOLDEN PARACHUTE
AND INDEMNIFICATION PAYMENTS
1. The authority citation for part 1231
continues to read as follows:
■
Authority: 12 U.S.C. 4518(e), 4518a, 4526.
2. In § 1231.2 add the definitions of
‘‘Indemnification payment’’ and
‘‘Liability or legal expense’’ in
alphabetical order to read as follows:
■
§ 1231.2
Definitions.
*
*
*
*
*
Indemnification payment means any
payment (or any agreement to make any
payment) by any regulated entity or the
OF for the benefit of any current or
former entity-affiliated party, to pay or
reimburse such person for any liability
or legal expense.
Liability or legal expense means—
(1) Any legal or other professional
expense incurred in connection with
any claim, proceeding, or action;
(2) The amount of, and the cost
incurred in connection with, any
settlement of any claim, proceeding, or
action; and
(3) The amount of, and any cost
incurred in connection with, any
judgment or penalty imposed with
respect to any claim, proceeding, or
action.
*
*
*
*
*
■ 3. Add § 1231.4 to read as follows:
§ 1231.4
Indemnification payments.
(a) Prohibited indemnification
payments. Except as permitted in
paragraph (b) of this section, a regulated
entity or the OF may not make
indemnification payments with respect
to an administrative proceeding or civil
action that has been initiated by FHFA.
(b) Permissible indemnification
payments. A regulated entity or the OF
may pay:
(1) Premiums for professional liability
insurance or fidelity bonds for directors
and officers, to the extent that the
insurance or fidelity bond covers
expenses and restitution, but not a
judgment in favor of FHFA or a civil
money penalty.
(2) Expenses of defending an action,
subject to the entity-affiliated party’s
agreement to repay those expenses if the
entity-affiliated party either:
(i) When the proceeding results in an
order, is not exonerated of the charges
that the expenses specifically relate to;
or
(ii) Enters into a settlement of those
charges in which the entity-affiliated
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party admits culpability with respect to
them; or
(iii) Is subject to a final prohibition
order under 12 U.S.C. 4636a.
(3) Amounts due under an
indemnification agreement entered into
with a named entity-affiliated party on
or prior to [DATE OF PUBLICATION OF
THE FINAL RULE IN THE FEDERAL
REGISTER].
(c) Process; factors. With respect to
payments under paragraph (b)(2) of this
section:
(1) The board of directors of the
regulated entity or the OF must conduct
a due investigation and make a written
determination in good faith that:
(i) The entity-affiliated party acted in
good faith and in a manner that he or
she reasonably believed to be in the best
interests of the regulated entity or the
OF; and
(ii) Such payments will not materially
adversely affect the safety and
soundness of the regulated entity or the
OF.
(2) The entity-affiliated party may not
participate in the board’s deliberations
or decision.
(3) If a majority of the board are
respondents in the action, the remaining
board members may approve payment
after obtaining written opinion of
outside counsel that the conditions of
this regulation have been met.
(4) If all of the board members are
respondents, they may approve payment
after obtaining written opinion of
outside counsel that the conditions of
this regulation have been met.
(d) Scope. This section does not apply
to a regulated entity operating in
conservatorship or receivership or to a
limited-life regulated entity.
Dated: September 13, 2016.
Melvin L. Watt,
Director, Federal Housing Finance Agency.
[FR Doc. 2016–22483 Filed 9–19–16; 8:45 am]
BILLING CODE 8070–01–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2016–6137; Notice No. 25–
16–05–SC]
Special Conditions: The Boeing
Company Model 787–10 Airplane;
Aeroelastic Stability Requirements,
Flaps-Up Vertical Modal-Suppression
System
Federal Aviation
Administration (FAA), DOT.
AGENCY:
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Federal Register / Vol. 81, No. 182 / Tuesday, September 20, 2016 / Proposed Rules
Notice of proposed special
conditions.
ACTION:
This action proposes special
conditions for the Boeing Company
(Boeing) Model 787–10 airplane. This
airplane will have a novel or unusual
design feature when compared to the
state of technology envisioned in the
airworthiness standards for transportcategory airplanes. This design feature
is a flaps-up vertical modal-suppression
system. The applicable airworthiness
regulations do not contain adequate or
appropriate safety standards for this
design feature. These proposed 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: Send your comments on or
before November 4, 2016.
ADDRESSES: Send comments identified
by docket number FAA–2016–6137
using any of the following methods:
• Federal eRegulations Portal: Go to
https://www.regulations.gov/ and follow
the online instructions for sending your
comments electronically.
• Mail: Send comments to Docket
Operations, M–30, U.S. Department of
Transportation (DOT), 1200 New Jersey
Avenue SE., Room W12–140, West
Building Ground Floor, Washington, DC
20590–0001.
• Hand Delivery or Courier: Take
comments to Docket Operations in
Room W12–140 of the West Building
Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
• Fax: Fax comments to Docket
Operations at 202–493–2251.
Privacy: The FAA will post all
comments it receives, without change,
to https://www.regulations.gov/,
including any personal information the
commenter provides. Using the search
function of the docket Web site, anyone
can find and read the electronic form of
all comments received into any FAA
docket, including the name of the
individual sending the comment (or
signing the comment for an association,
business, labor union, etc.). DOT’s
complete Privacy Act Statement can be
found in the Federal Register published
on April 11, 2000 (65 FR 19477–19478),
as well as at
https://DocketsInfo.dot.gov/.
Docket: Background documents or
comments received may be read at
https://www.regulations.gov/ at any time.
Follow the online instructions for
accessing the docket or go to Docket
Operations in Room W12–140 of the
West Building Ground Floor at 1200
sradovich on DSK3GMQ082PROD with PROPOSALS
SUMMARY:
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New Jersey Avenue SE., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT:
Wael Nour, FAA, Airframe and Cabin
Safety Branch, ANM–115, Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington, 98057–3356;
telephone 425–227–2143; facsimile
425–227–1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take
part in this rulemaking by sending
written comments, data, or views. The
most helpful comments reference a
specific portion of the special
conditions, explain the reason for any
recommended change, and include
supporting data.
We will consider all comments we
receive by the closing date for
comments. We may change these special
conditions based on the comments we
receive.
Background
On July 30, 2013, Boeing applied for
an amendment to type certificate no.
T00021SE to include the new Model
787–10 airplane. This airplane is a
stretched-fuselage derivative of the 787–
9, currently approved under type
certificate no. T00021SE, with
maximum single-class seating capacity
of 440 passengers. The 787–10 has a
maximum takeoff weight of 560,000 lbs
and is powered by two General Electric
GEnx-1B/P2 or Rolls-Royce Trent 1000
engines.
Type Certification Basis
Under the provisions of Title 14, Code
of Federal Regulations (14 CFR) 21.101,
Boeing must show that the Model 787–
10 airplane meets the applicable
provisions of the regulations listed in
type certificate no. T00021SE or the
applicable regulations in effect on the
date of application for the change,
except for earlier amendments as agreed
upon by the FAA.
In addition, the certification basis
includes other regulations, special
conditions, and exemptions that are not
relevant to these proposed special
conditions. Type certificate no.
T00021SE will be updated to include a
complete description of the certification
basis for this airplane model.
If the Administrator finds that the
applicable airworthiness regulations
(i.e., 14 CFR part 25) do not contain
adequate or appropriate safety standards
for the Model 787–10 airplane because
of a novel or unusual design feature,
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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, or should any
other model already included on the
same type certificate be modified to
incorporate the same novel or unusual
design feature, these special conditions
would also apply to the other model
under § 21.101.
In addition to the applicable
airworthiness regulations and special
conditions, the Model 787–10 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 § 11.38, and they become part of
the type certification basis under
§ 21.101.
Novel or Unusual Design Features
The Model 787–10 airplane will
incorporate the following novel or
unusual design features:
A flaps-up vertical modal suppression
system.
Discussion
The Boeing Model 787–10 will add a
new flaps-up vertical modalsuppression (F0VMS) system to the
Normal mode of the primary flightcontrol system (PFCS). The F0VMS
system is needed to satisfy the flutterdamping margin requirements of
§ 25.629 and the means-of-compliance
provisions in advisory circular (AC)
25.629–1B. This system will be used in
lieu of typical methods of improving the
flutter characteristics of an airplane,
such as increasing the torsional stiffness
of the wing or adding wingtip ballast
weights.
The F0VMS system is an active
modal-suppression system that will
provide additional damping to an
already stable, but low-damped, 3Hz
symmetric wing, nacelle, and body
aeroelastic mode of the airplane. This
feedback-control system will
compensate for a flutter-damping
margin deficiency of the airplane and
maintain adequate damping margins to
flutter. The F0VMS system
accomplishes this by oscillating the
elevators, and, when needed, the
flaperons.
Because Boeing’s flutter analysis
shows that the 3Hz mode is stable and
does not flutter, the F0VMS system is
not an active flutter-suppression system,
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but, rather, a damping-augmentation
system. At this time, the FAA is not
prepared to accept an active fluttersuppression system that suppresses a
divergent flutter mode in the
operational or design envelope of the
airplane.
This will be the first time an active
modal-suppression system will be used
to compensate for a flutter-damping
margin deficiency for § 25.629
compliance, and the FAA intends to
take a conservative approach in the
technology’s application. The FAA
considers the use of this new active
modal-suppression system for flutter
compliance to be novel or unusual
when compared to the technology
envisioned in the current airworthiness
standards. Consequently, special
conditions are required in consideration
of the effects of this new system on the
aeroelastic stability of the airplane, both
in the normal and failed state, to
maintain the level of safety intended by
§ 25.629.
The stretched body of the 787–10
degrades the 3Hz symmetric wing,
nacelle, and body aeroelastic mode
relative to the 787–9. The 3Hz
aeroelastic mode of the 787–10 airplane
without the F0VMS system does not
meet the damping margin criteria of AC
25.629–1B within the operational
envelope, as well as the design
envelope, of the airplane. The 3Hz mode
is not predicted to flutter, but has a lack
of adequate flutter-damping margin for
the airplane. Boeing has determined that
typical methods of improving the flutter
characteristics of the airplane, such as
increasing the torsional stiffness of the
wing or adding wingtip ballast weights,
do not meet their business objectives.
Consequently, Boeing is adding a new
F0VMS system to the Normal mode of
the Model 787–10 airplane PFCS to
satisfy the flutter-damping margin
requirements of § 25.629, and means-ofcompliance provisions contained in AC
25.629–1B. The F0VMS system will be
active in certain parts of the flight
envelope when the flaps are retracted.
The F0VMS system is a feedbackcontrol system that adds damping to the
system’s 3Hz mode by oscillating the
elevators symmetrically. When the
elevators are expected to be ineffective
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due to blowdown or other limitations,
the flaperons are applied to augment or
supplant elevator-control input.
However, the flaperons are not as
effective as the elevators in providing
additional damping to the 3Hz mode.
The F0VMS system will be an integral
part of the PFCS Normal mode and use
existing hardware, including inertial
and air-data sensors. As such, the
F0VMS system is expected to be as
reliable as the Normal mode itself. In
other words, any failures that would
cause a loss of the F0VMS function
would also cause a loss of the Normal
mode. FAA issue paper SA–17,
‘‘Command Signal Integrity,’’ requires
that the probability of an automatic
change from Normal mode to a degraded
mode of the PFCS should occur with a
frequency less than 10¥7 per flight hour,
irrespective of flight phase. This
reliability is acceptable for the F0VMS
system meeting the flutter-damping
margins of § 25.629 and AC 25.629–1B,
and the requirements of these special
conditions. The F0VMS function is only
available in the PFCS Normal mode, and
not available in the Secondary or Direct
modes. However, the PFCS Secondary
and Direct modes include a simplified
modal-suppression function, which
provides additional damping margin.
In addition to the Model 787–10
airplane needing the F0VMS
functionality for flutter compliance, this
functionality will also be used for active
nacelle gust-load alleviation (NGLA),
because the low damping exhibited by
the 3Hz mode adversely affects nacelle
gust loads. Therefore, the Boeing Model
787–9 airplane NGLA system will not
need to be carried over to the Model
787–10 airplane.
These proposed special conditions
contain the additional safety standards
that the Administrator considers
necessary to establish a level of safety
equivalent to that established by the
existing airworthiness standards.
Applicability
As discussed above, these special
conditions are applicable to the Boeing
Model 787–10 airplane. Should Boeing
apply at a later date for a change to the
type certificate to include another
model incorporating the same novel or
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unusual design feature, these special
conditions would apply to that model as
well.
Conclusion
This action affects only certain novel
or unusual design features on one model
series of airplane. It is not a rule of
general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
The authority citation for these
special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation
Administration (FAA) proposes the
following special conditions as part of
the type certification basis for Boeing
Model 787–10 airplanes.
The following special conditions are
proposed to address the aeroelastic
stability of the 787–10 airplane with the
F0VMS system as an integral part of the
PFCS Normal mode:
■
Analytical Flutter-Clearance
Requirements
1. The airplane in the PFCS Normal
mode (which includes F0VMS) must
meet the nominal (no failures) flutter
and aeroelastic stability requirements of
§ 25.629(b)(1), and the damping-margin
criteria of AC 25.629–1B, Section
7.1.3.3. Figure 1, below, illustrates the
Damping versus Airspeed plot.
a. The aeroservoelastic analysis must
take into account the effect of the
following items:
i. Significant structural and
aerodynamic nonlinearities.
ii. Significant F0VMS nonlinearities,
including control-surface rate and
displacement saturation, and
blowdown.
iii. The range of design maneuver load
factors.
iv. Control surface freeplay.
v. Any other items that may affect the
performance of the F0VMS system in
maintaining adequate modal damping
margins.
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KEAS) to zero damping margin to flutter
at 1.15 VD/1.15 MD, limited to Mach 1.0.
That is, the 3Hz mode should not cross
the g = 0.015 line below VD, or the g =
0.03 line below 1.15 VD, assuming the
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use of analysis Method 1 of AC 25.629–
1B, Section 7.1.3.3. Figure 2, below,
illustrates the Damping versus Airspeed
plot.
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2. The airplane in the PFCS Normal
mode, but with the F0VMS system
inoperative, must exhibit a damping
margin to flutter of 0.015g within the
VD/MD envelope, linearly decreasing (in
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Federal Register / Vol. 81, No. 182 / Tuesday, September 20, 2016 / Proposed Rules
3. The airplane in the PFCS Normal
mode (which includes F0VMS) must
meet the fail-safe flutter and aeroelastic
stability requirements of § 25.629(b)(2),
and the damping-margin criteria of AC
25.629–1B, Section 7.1.3.5.
4. The airplane in the PFCS
Secondary and Direct modes must meet
the fail-safe flutter and aeroelasticstability requirements of § 25.629(b)(2),
and the damping-margin criteria of AC
25.629–1B, Section 7.1.3.5.
Issued in Renton, Washington, on
September 9, 2016.
Michael Kaszycki,
Assistant Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. 2016–22547 Filed 9–19–16; 8:45 am]
BILLING CODE 4910–13–P
Publication of list of rules
scheduled for review.
ACTION:
The Securities and Exchange
Commission is publishing a list of rules
to be reviewed pursuant to Section 610
of the Regulatory Flexibility Act. The
list is published to provide the public
with notice that these rules are
scheduled for review by the agency and
to invite public comment on whether
the rules should be continued without
change, or should be amended or
rescinded to minimize any significant
economic impact of the rules upon a
substantial number of such small
entities.
SUMMARY:
Comments should be submitted
by October 20, 2016.
DATES:
Comments may be
submitted by any of the following
methods:
ADDRESSES:
sradovich on DSK3GMQ082PROD with PROPOSALS
SECURITIES AND EXCHANGE
COMMISSION
Electronic Comments
• Use the Commission’s Internet
comment form (https://www.sec.gov/
[Release Nos. 33–10209, 34–78845, 39–2511, rules/other.shtml); or
IA–4530, IC–32263; File No. S7–21–16]
• Send an email to rule-comments@
sec.gov. Please include File Number
List of Rules To Be Reviewed Pursuant [S7–21–16] on the subject line; or
to the Regulatory Flexibility Act
• Use the Federal eRulemaking Portal
(https://www.regulations.gov). Follow the
AGENCY: Securities and Exchange
instructions for submitting comments.
Commission.
17 CFR Chapter II
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Paper Comments
• Send paper comments to Brent
Fields, Secretary, Securities and
Exchange Commission, 100 F Street NE.,
Washington, DC 20549–1090.
All submissions should refer to File No.
S7–21–16. This file number should be
included on the subject line if email is
used. To help us process and review
your comments more efficiently, please
use only one method. The Commission
will post all comments on the
Commission’s Internet Web site (https://
www.sec.gov/rules/other.shtml).
Comments also are available for Web
site viewing and printing in the
Commission’s Public Reference Room,
100 F Street NE., Washington, DC 20549
on official business days between the
hours of 10:00 a.m. and 3:00 p.m. All
comments received will be posted
without change; we do not edit personal
identifying information from
submissions. You should submit only
information that you wish to make
available publicly.
FOR FURTHER INFORMATION CONTACT:
Anne Sullivan, Office of the General
Counsel, 202–551–5019.
SUPPLEMENTARY INFORMATION: The
Regulatory Flexibility Act (‘‘RFA’’),
codified at 5 U.S.C. 600–611, requires
an agency to review its rules that have
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64364
]]>Agencies
[Federal Register Volume 81, Number 182 (Tuesday, September 20, 2016)]
[Proposed Rules]
[Pages 64360-64364]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-22547]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2016-6137; Notice No. 25-16-05-SC]
Special Conditions: The Boeing Company Model 787-10 Airplane;
Aeroelastic Stability Requirements, Flaps-Up Vertical Modal-Suppression
System
AGENCY: Federal Aviation Administration (FAA), DOT.
[[Page 64361]]
ACTION: Notice of proposed special conditions.
-----------------------------------------------------------------------
SUMMARY: This action proposes special conditions for the Boeing Company
(Boeing) Model 787-10 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 a flaps-up vertical modal-suppression
system. The applicable airworthiness regulations do not contain
adequate or appropriate safety standards for this design feature. These
proposed 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: Send your comments on or before November 4, 2016.
ADDRESSES: Send comments identified by docket number FAA-2016-6137
using any of the following methods:
Federal eRegulations Portal: Go to https://www.regulations.gov/ and follow the online instructions for sending
your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without
change, to https://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at https://DocketsInfo.dot.gov/.
Docket: Background documents or comments received may be read at
https://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE.,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Wael Nour, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98057-
3356; telephone 425-227-2143; facsimile 425-227-1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
We will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
we receive.
Background
On July 30, 2013, Boeing applied for an amendment to type
certificate no. T00021SE to include the new Model 787-10 airplane. This
airplane is a stretched-fuselage derivative of the 787-9, currently
approved under type certificate no. T00021SE, with maximum single-class
seating capacity of 440 passengers. The 787-10 has a maximum takeoff
weight of 560,000 lbs and is powered by two General Electric GEnx-1B/P2
or Rolls-Royce Trent 1000 engines.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.101, Boeing must show that the Model 787-10 airplane meets the
applicable provisions of the regulations listed in type certificate no.
T00021SE or the applicable regulations in effect on the date of
application for the change, except for earlier amendments as agreed
upon by the FAA.
In addition, the certification basis includes other regulations,
special conditions, and exemptions that are not relevant to these
proposed special conditions. Type certificate no. T00021SE will be
updated to include a complete description of the certification basis
for this airplane model.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Model 787-10 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 or similar
novel or unusual design feature, or should any other model already
included on the same type certificate be modified to incorporate 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 Model 787-10 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. 21.101.
Novel or Unusual Design Features
The Model 787-10 airplane will incorporate the following novel or
unusual design features:
A flaps-up vertical modal suppression system.
Discussion
The Boeing Model 787-10 will add a new flaps-up vertical modal-
suppression (F0VMS) system to the Normal mode of the primary flight-
control system (PFCS). The F0VMS system is needed to satisfy the
flutter-damping margin requirements of Sec. 25.629 and the means-of-
compliance provisions in advisory circular (AC) 25.629-1B. This system
will be used in lieu of typical methods of improving the flutter
characteristics of an airplane, such as increasing the torsional
stiffness of the wing or adding wingtip ballast weights.
The F0VMS system is an active modal-suppression system that will
provide additional damping to an already stable, but low-damped, 3Hz
symmetric wing, nacelle, and body aeroelastic mode of the airplane.
This feedback-control system will compensate for a flutter-damping
margin deficiency of the airplane and maintain adequate damping margins
to flutter. The F0VMS system accomplishes this by oscillating the
elevators, and, when needed, the flaperons.
Because Boeing's flutter analysis shows that the 3Hz mode is stable
and does not flutter, the F0VMS system is not an active flutter-
suppression system,
[[Page 64362]]
but, rather, a damping-augmentation system. At this time, the FAA is
not prepared to accept an active flutter-suppression system that
suppresses a divergent flutter mode in the operational or design
envelope of the airplane.
This will be the first time an active modal-suppression system will
be used to compensate for a flutter-damping margin deficiency for Sec.
25.629 compliance, and the FAA intends to take a conservative approach
in the technology's application. The FAA considers the use of this new
active modal-suppression system for flutter compliance to be novel or
unusual when compared to the technology envisioned in the current
airworthiness standards. Consequently, special conditions are required
in consideration of the effects of this new system on the aeroelastic
stability of the airplane, both in the normal and failed state, to
maintain the level of safety intended by Sec. 25.629.
The stretched body of the 787-10 degrades the 3Hz symmetric wing,
nacelle, and body aeroelastic mode relative to the 787-9. The 3Hz
aeroelastic mode of the 787-10 airplane without the F0VMS system does
not meet the damping margin criteria of AC 25.629-1B within the
operational envelope, as well as the design envelope, of the airplane.
The 3Hz mode is not predicted to flutter, but has a lack of adequate
flutter-damping margin for the airplane. Boeing has determined that
typical methods of improving the flutter characteristics of the
airplane, such as increasing the torsional stiffness of the wing or
adding wingtip ballast weights, do not meet their business objectives.
Consequently, Boeing is adding a new F0VMS system to the Normal mode of
the Model 787-10 airplane PFCS to satisfy the flutter-damping margin
requirements of Sec. 25.629, and means-of-compliance provisions
contained in AC 25.629-1B. The F0VMS system will be active in certain
parts of the flight envelope when the flaps are retracted. The F0VMS
system is a feedback-control system that adds damping to the system's
3Hz mode by oscillating the elevators symmetrically. When the elevators
are expected to be ineffective due to blowdown or other limitations,
the flaperons are applied to augment or supplant elevator-control
input. However, the flaperons are not as effective as the elevators in
providing additional damping to the 3Hz mode.
The F0VMS system will be an integral part of the PFCS Normal mode
and use existing hardware, including inertial and air-data sensors. As
such, the F0VMS system is expected to be as reliable as the Normal mode
itself. In other words, any failures that would cause a loss of the
F0VMS function would also cause a loss of the Normal mode. FAA issue
paper SA-17, ``Command Signal Integrity,'' requires that the
probability of an automatic change from Normal mode to a degraded mode
of the PFCS should occur with a frequency less than 10-7 per
flight hour, irrespective of flight phase. This reliability is
acceptable for the F0VMS system meeting the flutter-damping margins of
Sec. 25.629 and AC 25.629-1B, and the requirements of these special
conditions. The F0VMS function is only available in the PFCS Normal
mode, and not available in the Secondary or Direct modes. However, the
PFCS Secondary and Direct modes include a simplified modal-suppression
function, which provides additional damping margin.
In addition to the Model 787-10 airplane needing the F0VMS
functionality for flutter compliance, this functionality will also be
used for active nacelle gust-load alleviation (NGLA), because the low
damping exhibited by the 3Hz mode adversely affects nacelle gust loads.
Therefore, the Boeing Model 787-9 airplane NGLA system will not need to
be carried over to the Model 787-10 airplane.
These proposed special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
Applicability
As discussed above, these special conditions are applicable to the
Boeing Model 787-10 airplane. Should Boeing apply at a later date for a
change to the type certificate to include another model incorporating
the same novel or unusual design feature, these special conditions
would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model series of airplane. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
0
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Boeing Model 787-10 airplanes.
The following special conditions are proposed to address the
aeroelastic stability of the 787-10 airplane with the F0VMS system as
an integral part of the PFCS Normal mode:
Analytical Flutter-Clearance Requirements
1. The airplane in the PFCS Normal mode (which includes F0VMS) must
meet the nominal (no failures) flutter and aeroelastic stability
requirements of Sec. 25.629(b)(1), and the damping-margin criteria of
AC 25.629-1B, Section 7.1.3.3. Figure 1, below, illustrates the Damping
versus Airspeed plot.
a. The aeroservoelastic analysis must take into account the effect
of the following items:
i. Significant structural and aerodynamic nonlinearities.
ii. Significant F0VMS nonlinearities, including control-surface
rate and displacement saturation, and blowdown.
iii. The range of design maneuver load factors.
iv. Control surface freeplay.
v. Any other items that may affect the performance of the F0VMS
system in maintaining adequate modal damping margins.
[[Page 64363]]
[GRAPHIC] [TIFF OMITTED] TP20SE16.024
2. The airplane in the PFCS Normal mode, but with the F0VMS system
inoperative, must exhibit a damping margin to flutter of 0.015g within
the VD/MD envelope, linearly decreasing (in KEAS)
to zero damping margin to flutter at 1.15 VD/1.15
MD, limited to Mach 1.0. That is, the 3Hz mode should not
cross the g = 0.015 line below VD, or the g = 0.03 line
below 1.15 VD, assuming the use of analysis Method 1 of AC
25.629-1B, Section 7.1.3.3. Figure 2, below, illustrates the Damping
versus Airspeed plot.
[[Page 64364]]
[GRAPHIC] [TIFF OMITTED] TP20SE16.025
3. The airplane in the PFCS Normal mode (which includes F0VMS) must
meet the fail-safe flutter and aeroelastic stability requirements of
Sec. 25.629(b)(2), and the damping-margin criteria of AC 25.629-1B,
Section 7.1.3.5.
4. The airplane in the PFCS Secondary and Direct modes must meet
the fail-safe flutter and aeroelastic-stability requirements of Sec.
25.629(b)(2), and the damping-margin criteria of AC 25.629-1B, Section
7.1.3.5.
Issued in Renton, Washington, on September 9, 2016.
Michael Kaszycki,
Assistant Manager, Transport Airplane Directorate, Aircraft
Certification Service.
[FR Doc. 2016-22547 Filed 9-19-16; 8:45 am]
BILLING CODE 4910-13-P
