Rule2021-21540
Special Conditions: Boeing Commercial Airplanes Model 777-9 Airplane; Operation Without Normal Electrical Power
Primary source
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Published
October 4, 2021
Effective
October 4, 2021
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
These special conditions are issued for the Boeing Commercial Airplanes (Boeing) Model 777-9 series 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 electrical and electronic systems that perform critical functions, the loss of which could be catastrophic to the airplane. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
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<title>Federal Register, Volume 86 Issue 189 (Monday, October 4, 2021)</title>
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[Federal Register Volume 86, Number 189 (Monday, October 4, 2021)]
[Rules and Regulations]
[Pages 54588-54590]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-21540]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2021-0894; Special Conditions No. 25-791-SC]
Special Conditions: Boeing Commercial Airplanes Model 777-9
Airplane; Operation Without Normal Electrical Power
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Boeing Commercial
Airplanes (Boeing) Model 777-9 series 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 electrical and electronic
systems that perform critical functions, the loss of which could be
catastrophic to the airplane. The applicable airworthiness regulations
do not contain adequate or appropriate safety standards for this design
feature. These special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
DATES: This action is effective on Boeing on October 4, 2021. Send
comments on or before November 18, 2021.
ADDRESSES: Send comments identified by Docket No. FAA-2021-0894 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
<bullet> Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: Except for Confidential Business Information (CBI) as
described in the following paragraph, and other information as
described in 14 CFR 11.35, the FAA will post all comments received
without change to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, including any personal
information you provide. The FAA will also post a report summarizing
each substantive verbal contact received about these special
conditions.
Confidential Business Information: Confidential Business
Information (CBI) is commercial or financial information that is both
customarily and actually treated as private by its owner. Under the
Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from
public disclosure. If your comments responsive to these special
conditions contain commercial or financial information that is
customarily treated as private, that you actually treat as private, and
that is relevant or responsive to these special conditions, it is
important that you clearly designate the submitted comments as CBI.
Please mark each page of your submission containing CBI as ``PROPIN.''
The FAA will treat such marked submissions as confidential under the
FOIA, and the indicated comments will not be placed in the public
docket of these special conditions. Submissions containing CBI should
be sent to Steve Slotte, Aircraft Systems, AIR-623, Technical
Innovation Policy Branch, Policy and Innovation Division, Aircraft
Certification Service, Federal Aviation Administration, 2200 South
216th Street, Des Moines, Washington 98198; telephone and fax 206-231-
3160;
[[Page 54589]]
<a href="/cdn-cgi/l/email-protection#83d0f7e6f5e6add0efecf7f7e6c3e5e2e2ade4ecf5"><span class="__cf_email__" data-cfemail="86d5f2e3f0e3a8d5eae9f2f2e3c6e0e7e7a8e1e9f0">[email protected]</span></a>. Comments the FAA receives, which are not
specifically designated as CBI, will be placed in the public docket for
these special conditions.
Docket: Background documents or comments received may be read at
<a href="https://www.regulations.gov/">https://www.regulations.gov/</a> at any time. Follow the online
instructions for accessing the docket or go to Docket Operations in
Room W12-140 of the West Building Ground Floor at 1200 New Jersey
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Stephen Slotte, Aircraft Systems, AIR-
623, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax (206) 231-3163; <a href="/cdn-cgi/l/email-protection#6f3c1b0a190a413c03001b1b0a2f090e0e41080019"><span class="__cf_email__" data-cfemail="491a3d2c3f2c671a25263d3d2c092f2828672e263f">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: The substance of these special conditions
has been published in the Federal Register for public comment in
several prior instances with no substantive comments received.
Therefore, the FAA has determined that prior public notice and comment
are unnecessary, and finds that, for the same reason, good cause exists
for adopting these special conditions upon publication in the Federal
Register.
Comments Invited
The FAA invites interested people to take part in this rulemaking
by sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
The FAA will consider all comments received by the closing date for
comments. The FAA may change these special conditions based on the
comments received.
Background
On September 30, 2018, Boeing applied for an amendment to Type
Certificate No. T00001SE to include the new Model 777-9 series
airplane. The Boeing Model 777-9 airplane, which is a derivative of the
Boeing Model 777 airplane currently approved under Type Certificate No.
T00001SE, is a twin-engine, transport-category airplane with seating
for 495 passengers, and a maximum takeoff weight of 775,000 lbs.
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR), Sec. 21.101, Boeing must show that the Model 777-9 series
airplane meets the applicable provisions of the regulations listed in
Type Certificate No. T00001SE, or the applicable regulations in effect
on the date of application for the change, except for earlier
amendments as agreed upon by the FAA.
If the Administrator finds that the applicable airworthiness
regulations (e.g., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Boeing Model 777-9 series airplane
because of a novel or unusual design feature, special conditions are
prescribed under the provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, 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 Boeing Model 777-9 series 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 Boeing Model 777-9 series airplane will incorporate the
following novel or unusual design feature:
Electrical and electronic systems that perform critical functions,
the loss of which may result in loss of flight controls and other
critical systems and may be catastrophic to the airplane.
Discussion
The Boeing Model 777-9 series airplane has a fly-by-wire flight
control system that requires a continuous source of electrical power in
order to maintain an operable flight control system. Section
25.1351(d), Operation without normal electrical power, requires safe
operation in visual flight rule (VFR) conditions for at least five
minutes after loss of normal electrical power excluding the battery.
This rule is structured around a traditional design using mechanical
control cables and linkages for flight control. These manual controls
allow the crew to maintain aerodynamic control of the airplane for an
indefinite period of time after loss of all electrical power. Under
these conditions, a mechanical flight control system provides the crew
with the ability to fly the airplane while attempting to identify the
cause of the electrical failure, restart engine(s) if necessary, and
attempt to re-establish some of the electrical power generation
capability.
A critical assumption in Sec. 25.1351(d) is that the airplane is
in VFR conditions at the time of the failure. This is not a valid
assumption in today's airline operating environment where airplanes fly
much of the time in instrument meteorological conditions (IMC) on air
traffic control defined flight paths. Another assumption in the
existing rule is that the loss of all normal electrical power is the
result of the loss of all engines. The five-minute period in the rule
is to allow at least one engine to be restarted following an all-engine
power loss in order to continue the flight to a safe landing. However,
service experience on airplane models with similar electrical power
system architecture as the Boeing Model 777-9 airplane has shown that
at least the temporary loss of all electrical power for causes other
than all-engine failure is not extremely improbable.
To maintain the same level of safety envisioned by the existing
rule with traditional mechanical flight controls, the Boeing Model 777-
9 series airplane design must not be time-limited in its operation
under all reasonably foreseeable conditions, including loss of all
normal sources of engine or auxiliary power unit (APU)-generated
electrical power. Unless Boeing can show that the non-restorable loss
of the engine and APU power sources is extremely improbable, Boeing
must demonstrate that the airplanes can maintain safe flight and
landing (including steering and braking on the ground for airplanes
using steer/brake-by-wire and/or fly-by-wire speed brake panels) with
the use of its emergency/alternate electrical power systems. These
electrical power systems, or the minimum restorable electrical power
sources, must be able to power loads that are essential for continued
safe flight and landing, including those required for the maximum
length of approved flight diversion.
These special conditions contain the additional safety standards
that the Administrator considers necessary to establish a level of
safety equivalent to that established by the existing airworthiness
standards.
[[Page 54590]]
Applicability
As discussed above, these special conditions are applicable to the
Boeing Model 777-9 series 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 a certain novel or unusual design feature
on one model series of airplanes. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702,
44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for the Boeing Commercial Airplanes Model
777-9 series airplanes.
In lieu of 14 CFR 25.1351(d), the following special conditions
apply:
(a) The applicant must show by test or a combination of test and
analysis that the airplane is capable of continued safe flight and
landing with all normal electrical power sources inoperative, as
prescribed by paragraphs (a)(1) and (a)(2), below. For purposes of
these special conditions, normal sources of electrical power generation
do not include any alternate power sources such as the battery, ram air
turbine, or independent power systems such as the flight control
permanent magnet generating system. In showing capability for continued
safe flight and landing, the applicant must account for systems
capability, effects on crew workload and operating conditions, and the
physiological needs of the flightcrew and passengers for the longest
diversion time for which the applicant is seeking approval.
(1) In showing compliance with this requirement, the applicant must
account for common-cause failures, cascading failures, and zonal
physical threats.
(2) The applicant may consider the ability to restore operation of
portions of the electrical power generation and distribution system if
it can be shown that unrecoverable loss of those portions of the system
is extremely improbable. The design must provide an alternative source
of electrical power for the time required to restore the minimum
electrical power generation capability required for safe flight and
landing. The applicant may exclude unrecoverable loss of all engines
when showing compliance with this requirement.
(b) Regardless of any electrical generation and distribution system
recovery capability shown under paragraph (a) of these special
conditions, sufficient electrical system capability must be provided
to:
(1) Allow time to descend, with all engines inoperative, at the
speed that provides the best glide distance, from the maximum operating
altitude to the top of the engine restart envelope, and
(2) Subsequently allow multiple start attempts of the engines and
auxiliary power unit (APU). The design must provide this capability in
addition to the electrical capability required by existing part 25
requirements related to operation with all engines inoperative.
(c) The airplane emergency electrical power system must be designed
to supply:
(1) Electrical power required for immediate safety, which must
continue to operate without the need for crew action following the loss
of the normal electrical power, for a duration sufficient to allow
reconfiguration to provide a non-time-limited source of electrical
power.
(2) Electrical power required for continued safe flight and landing
for the maximum diversion time.
(d) If the applicant uses APU-generated electrical power to satisfy
the requirements of these special conditions, and if reaching a
suitable runway for landing is beyond the capacity of the battery
systems, then the APU must be able to be started under any foreseeable
flight condition prior to the depletion of the battery or the
restoration of normal electrical power, whichever occurs first. Flight
test must demonstrate this capability at the most critical condition.
(1) The applicant must show that the APU will provide adequate
electrical power for continued safe flight and landing.
(2) The operating limitations section of the airplane flight manual
(AFM) must incorporate non-normal procedures that direct the pilot to
take appropriate actions to activate the APU after loss of normal
engine-driven generated electrical power.
(e) As part of showing compliance with these special conditions,
the tests to demonstrate loss of all normal electrical power must also
take into account the following:
(1) The assumption that the failure condition occurs during night
instrument meteorological conditions (IMC) at the most critical phase
of the flight, relative to the worst possible electrical power
distribution and equipment-loads-demand condition.
(2) After the un-restorable loss of normal engine generator power,
the airplane engine restart capability is provided and operations
continued in IMC.
(3) The airplane is demonstrated to be capable of continued safe
flight and landing. The length of time must be computed based on the
maximum diversion time capability for which the airplane is being
certified. The applicant must account for airspeed reductions resulting
from the associated failure or failures.
(4) The airplane must provide adequate indication of loss of normal
electrical power to direct the pilot to the non-normal procedures, and
the operating limitations section of the AFM must incorporate non-
normal procedures that will direct the pilot to take appropriate
actions.
Issued in Kansas City, Missouri, on September 29, 2021.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2021-21540 Filed 10-1-21; 8:45 am]
BILLING CODE 4910-13-P
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