Special Conditions: Boeing Model 747-8/-8F Airplanes; Additional Airframe Structural Design Requirements Related to Sudden Engine Stoppage Due to Fan Blade Failures, 40482-40484 [E9-19249]
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Federal Register / Vol. 74, No. 154 / Wednesday, August 12, 2009 / Rules and Regulations
V′ = Clearance speed as defined by
§ 25.629(b)(2).
V″ = Clearance speed as defined by
§ 25.629(b)(1).
Qj = (Tj)(Pj) where:
Tj = Average time spent in failure condition
j (in hours)
Pj = Probability of occurrence of failure mode
j (per hour)
jlentini on DSKJ8SOYB1PROD with RULES
Note: If Pj is greater than 10¥3 per flight
hour, then the flutter clearance speed must
not be less than V″.
(6) Freedom from aeroelastic
instability must also be shown up to V′
in Figure 3 above, for any probable
system failure condition combined with
any damage required or selected for
investigation by § 25.571(b).
Consideration of certain failure
conditions may be required by other
sections of part 25 regardless of
calculated system reliability. Where
analysis shows the probability of these
failure conditions to be less than 10¥9,
criteria other than those specified in this
paragraph may be used for structural
substantiation to show continued safe
flight and landing.
4. Failure indications. For system
failure detection and indication, the
following apply:
(a) The system must be checked for
failure conditions, not extremely
improbable, that degrade the structural
capability below the level required by
part 25 or significantly reduce the
reliability of the remaining system. As
far as reasonably practicable, the flight
crew must be made aware of these
failures before flight. Certain elements
of the control system, such as
mechanical and hydraulic components,
may use special periodic inspections,
and electronic components may use
daily checks, in lieu of detection and
indication systems to achieve the
objective of this requirement. These
Certification Maintenance Requirements
(CMRs) must be limited to components
that are not readily detectable by normal
detection and indication systems and
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Jkt 217001
where service history shows that
inspections will provide an adequate
level of safety.
(b) The existence of any failure
condition, not extremely improbable,
during flight that could significantly
affect the structural capability of the
airplane and for which the associated
reduction in airworthiness can be
minimized by suitable flight limitations,
must be signaled to the flight crew. For
example, failure conditions that result
in a factor of safety between the airplane
strength and the loads of subpart C
below 1.25, or flutter margins below V″,
must be signaled to the crew during
flight.
5. Dispatch with known failure
conditions. If the airplane is to be
dispatched in a known system failure
condition that affects structural
performance, or affects the reliability of
the remaining system to maintain
structural performance, then the
provisions of this special condition
must be met, including the provisions of
paragraph 2 for the dispatched
condition, and paragraph 3 for
subsequent failures. Expected
operational limitations may be taken
into account in establishing Pj as the
probability of failure occurrence for
determining the safety margin in Figure
1. Flight limitations and expected
operational limitations may be taken
into account in establishing Qj as the
combined probability of being in the
dispatched failure condition and the
subsequent failure condition for the
safety margins in Figures 2 and 3. These
limitations must be such that the
probability of being in this combined
failure state and then subsequently
encountering limit load conditions is
extremely improbable. No reduction in
these safety margins is allowed if the
subsequent system failure rate is greater
than 10¥3 per hour.
PO 00000
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Issued in Renton, Washington, on July 29,
2009.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E9–19246 Filed 8–11–09; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM399; Special Conditions No.
25–387–SC]
Special Conditions: Boeing Model 747–
8/–8F Airplanes; Additional Airframe
Structural Design Requirements
Related to Sudden Engine Stoppage
Due to Fan Blade Failures
AGENCY: Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
SUMMARY: These special conditions are
issued for Boeing Model 747–8/–8F
airplanes. These airplanes will have a
novel or unusual design feature(s)
associated with an increased engine size
when compared to previous model
airplanes. These larger engines with
larger bypass fans are capable of
producing higher and more complex
dynamic loads than previously
experienced in older designs. 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: Effective Date: September 11,
2009.
FOR FURTHER INFORMATION CONTACT:
Mark Freisthler, FAA, Airframe & Cabin
E:\FR\FM\12AUR1.SGM
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40482
Federal Register / Vol. 74, No. 154 / Wednesday, August 12, 2009 / Rules and Regulations
Safety Branch, ANM–115, Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind
Avenue, SW., Renton, Washington
98057–3356; telephone (425) 227–1119;
facsimile (425) 227–1149.
SUPPLEMENTARY INFORMATION:
jlentini on DSKJ8SOYB1PROD with RULES
Background
On November 4, 2005, The Boeing
Company, PO Box 3707, Seattle, WA,
98124, applied for an amendment to
Type Certificate Number A20WE to
include the new Model 747–8 passenger
airplane and the new Model 747–8F
freighter airplane. The Model 747–8 and
the Model 747–8F are derivatives of the
747–400 and the 747–400F,
respectively. Both the Model 747–8 and
the Model 747–8F are four-engine jet
transport airplanes that will have a
maximum takeoff weight of 970,000
pounds and new General Electric GEnx2B67 engines. The Model 747–8 will
have two flight crew and the capacity to
carry 660 passengers. The Model 747–
8F will have two flight crew and a zero
passenger capacity, although Boeing has
submitted a petition for exemption to
allow the carriage of supernumeraries.
Type Certification Basis
Under the provisions of Title 14 Code
of Federal Regulations (14 CFR) 21.101,
Boeing must show that the Model 747–
8 and 747–8F airplanes (hereafter
referred to as the 747–8/–8F) as
changed, continue to meet the
applicable provisions of 14 CFR part 25,
as amended by Amendments 25–1
through 25–117, except for earlier
amendments as agreed upon by the
FAA. These regulations will be
incorporated into Type Certificate No.
A20WE after type certification approval
of the 747–8/–8F.
If the Administrator finds that the
applicable airworthiness regulations
(i.e., part 25) do not contain adequate or
appropriate safety standards for the
747–8/–8F because of a novel or
unusual design feature, special
conditions are prescribed under the
provisions of § 21.16.
In addition to the applicable
airworthiness regulations and special
conditions, the 747–8/–8F 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.
Special conditions, as defined in
§ 11.19, are issued under § 11.38, and
become part of the type certification
basis under § 21.101.
Special conditions are initially
applicable to the model for which they
are issued. Should the type certificate
for that model be amended later to
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16:35 Aug 11, 2009
Jkt 217001
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, the special conditions
would also apply to the other model
under § 21.101.
Novel or Unusual Design Features
The Boeing Model 747–8/–8F
airplanes will incorporate the following
novel or unusual design features: Highbypass engines with a fan diameter
approximately twelve percent greater
than those currently installed on other
Boeing Model 747 airplanes.
Discussion
High-bypass engines with a fan
diameter approximately twelve percent
greater than those currently installed on
other Boeing Model 747 airplanes, such
as the 747–400 series, were not
envisioned when § 25.361 was adopted
in 1965. Section 25.361 addresses loads
imposed by engine seizure. Because of
the higher inertia of the rotating
components, worst case engine seizure
events become increasingly more severe
with increasing engine size.
Typically, the design torque loads
associated with typical failure scenarios
have been estimated by the engine
manufacturer. These loads are used by
the airframe manufacturer as limit
loads. Section 25.305 requires that
supporting structure be able to support
limit loads without detrimental
permanent deformation, meaning that
supporting structure should remain
serviceable after a limit load event.
Limit loads are expected to occur about
once in the lifetime of any airplane. For
turbine engine installations,
§ 25.361(b)(1) requires that the engine
mounts and supporting structures be
designed to withstand a ‘‘limit engine
torque load imposed by sudden engine
stoppage due to malfunction or
structural failure.’’
Since § 25.361(b)(1) was adopted the
size, configuration, and failure modes of
turbine engines have changed
significantly. Current engines are much
larger and are designed with large
bypass fans. In the failure event
prescribed by § 25.361 they produce
much higher transient loads on the
engine mounts and supporting structure
than previous designs. At the same time,
the likelihood of such an event
occurring in modern engines has
become less. The service history of
modern turbine engines shows that
engine seizures are rare events, much
less than what is typically expected for
‘‘limit’’ loads. While it is important for
PO 00000
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40483
the airplane to be able to support such
rare loads safely without failure, it is
unrealistic to expect that no permanent
deformation will occur.
Given this situation, the Aviation
Rulemaking Advisory Committee
(ARAC) has proposed a design standard
for today’s large engines. For the
commonly-occurring deceleration
events, the proposed standard would
require engine mounts and structures to
support maximum torques without
detrimental permanent deformation. For
the rare-but-severe engine seizure events
such as loss of any fan, compressor, or
turbine blade, the proposed standard
would require engine mounts and
structures to support maximum torques
without failure, but allow for some
deformation in the structure.
The FAA concludes that modern large
engines, including those on the 747–8/
–8F, are novel and unusual compared to
those envisioned when § 25.361(b)(1)
was adopted and thus warrant special
conditions. These special conditions
contain design criteria recommended by
the ARAC.
Discussion of Comments
Notice of proposed special conditions
No. 25–09–02–SC for the Boeing Model
747–8 and 747–8F airplanes was
published in the Federal Register on
April 8, 2009 (74 FR 15888). No
comments were received and the special
conditions are adopted as proposed.
Applicability
As discussed above, these special
conditions are applicable to Boeing
Model 747–8/–8F airplanes. 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 features, the special
conditions would apply to that model as
well.
Conclusion
This action affects only certain novel
or unusual design features of the Boeing
Model 747–8/–8F airplanes. 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 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 Model
E:\FR\FM\12AUR1.SGM
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40484
Federal Register / Vol. 74, No. 154 / Wednesday, August 12, 2009 / Rules and Regulations
jlentini on DSKJ8SOYB1PROD with RULES
747–8/–8F airplanes. The following
special conditions are in lieu of
§ 25.361(b):
1. For turbine engine installations, the
engine mounts, pylons and supporting
airframe primary structure (such as the
affected wing and fuselage primary
structure) must be designed to
withstand 1g level flight loads acting
simultaneously with the maximum
torque load, considered as limit load,
imposed by each of the following:
(a) Sudden engine deceleration due to
a malfunction which could result in a
temporary loss of power or thrust; and
(b) The maximum acceleration of the
engine.
2. For auxiliary power unit
installations, the power unit mounts
and supporting airframe primary
structure (such as the affected fuselage
primary structure) must be designed to
withstand 1g level flight loads acting
simultaneously with the maximum
torque load, considered as limit load,
imposed by each of the following:
(a) Sudden auxiliary power unit
deceleration due to malfunction or
structural failure; and
(b) The maximum acceleration of the
power unit.
3. For turbine engine installations, the
engine mounts, pylons and supporting
airframe primary structure (such as the
affected wing and fuselage primary
structure) must be designed to
withstand 1g flight loads acting
simultaneously with the transient
dynamic loads, considered as ultimate
load, imposed by each of the following:
(a) Sudden engine stoppage due to the
loss of any fan, compressor, or turbine
blade; and separately
(b) Where applicable to a specific
engine design, any other engine
structural failure that results in higher
loads.
4. The ultimate loads developed from
the conditions specified in paragraphs
3(a) and 3(b) are to be multiplied by a
factor of 1.0 when applied to engine
mounts and pylons and multiplied by a
factor of 1.25 when applied to the
supporting airframe primary structure
(such as the affected wing and fuselage
primary structure). In addition, the
airplane must be capable of continued
safe flight considering the aerodynamic
effects on controllability due to any
permanent deformation that results from
the conditions specified in paragraph 3,
above.
Issued in Renton, Washington, on July 29,
2009.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. E9–19249 Filed 8–11–09; 8:45 am]
BILLING CODE 4910–13–P
VerDate Nov<24>2008
16:35 Aug 11, 2009
Jkt 217001
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2009–0464; Directorate
Identifier 2008–NM–189–AD; Amendment
39–15992; AD 2008–16–09 R1]
RIN 2120–AA64
Airworthiness Directives; Short
Brothers Model SD3–60 Airplanes
AGENCY: Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule.
SUMMARY: We are revising an existing
airworthiness directive (AD) for the
products listed above. This AD results
from mandatory continuing
airworthiness information (MCAI)
originated by an aviation authority of
another country to identify and correct
an unsafe condition on an aviation
product. The MCAI describes the unsafe
condition as:
There have been several occurrences of
cracked elevator trim tab balance weight
attachment brackets, on one occasion, the
elevator trim tab mass balance weight bracket
separated from the aircraft. The loss of an
elevator trim tab mass balance weight bracket
has the potential to cause damage to an
aircraft, or cause serious injury to personnel.
*
*
*
*
*
We are issuing this AD to require
actions to correct the unsafe condition
on these products.
DATES: This AD becomes effective
September 16, 2009.
The Director of the Federal Register
previously approved the incorporation
by reference of certain publications
listed in this AD as of September 15,
2008 (73 FR 46543, August 11, 2008).
The Director of the Federal Register
previously approved the incorporation
by reference of a certain publication
listed in this AD as of March 14, 2005
(70 FR 9212, February 25, 2005).
The Director of the Federal Register
previously approved the incorporation
by reference of a certain other
publication listed in this AD as of
September August 3, 2004 (69 FR 38813,
June 29, 2004).
ADDRESSES: You may examine the AD
docket on the Internet at https://
www.regulations.gov or in person at the
U.S. Department of Transportation,
Docket Operations, M–30, West
Building Ground Floor, Room W12–140,
1200 New Jersey Avenue, SE.,
Washington, DC.
FOR FURTHER INFORMATION CONTACT:
Todd Thompson, Aerospace Engineer,
PO 00000
Frm 00014
Fmt 4700
Sfmt 4700
International Branch, ANM–116,
Transport Airplane Directorate, FAA,
1601 Lind Avenue, SW., Renton,
Washington 98057–3356; telephone
(425) 227–1175; fax (425) 227–1149.
SUPPLEMENTARY INFORMATION:
Discussion
We issued a notice of proposed
rulemaking (NPRM) to amend 14 CFR
part 39 to include an AD to revise AD
2008–16–09, amendment 39–15627 (73
FR 46543, August 11, 2008). The
existing AD applies to the products
identified in this AD. The NPRM was
published in the Federal Register on
May 20, 2009 (74 FR 23668). That
NPRM proposed to correct an unsafe
condition for the specified products.
Since we issued AD 2008–16–09,
Short Brothers advised that SD3–07–
6011xA brackets manufactured in 2005
or later have a life limit of 28,800 flight
hours, per Section 5–00–02 of the Short
Brothers SD360 Aircraft Maintenance
Manual (AMM), and as noted in
Appendix 1 of Shorts Alert Service
Bulletin SD360–55–A21, Revision 1,
dated March 29, 2007. In light of this,
we have revised the existing AD to
extend the life limit of any balance
weight bracket from 1,750 flight hours
to 28,800 flight hours. You may obtain
further information by examining
European Aviation Safety Agency
Airworthiness Directive 2007–0107–E,
dated April 18, 2007 (referred to after
this as ‘‘the MCAI’’), in the AD docket.
In addition, we removed paragraphs
(f) and (l)(1) of the existing AD from this
AD. Those paragraphs defined the use of
the term ‘‘service bulletin,’’ as used in
the AD.
Comments
We gave the public the opportunity to
participate in developing this AD. We
received no comments on the NPRM or
on the determination of the cost to the
public.
Conclusion
We reviewed the available data and
determined that air safety and the
public interest require adopting the AD
as proposed.
Differences Between This AD and the
MCAI or Service Information
We have reviewed the MCAI and
related service information and, in
general, agree with their substance. But
we might have found it necessary to use
different words from those in the MCAI
to ensure the AD is clear for U.S.
operators and is enforceable. In making
these changes, we do not intend to differ
substantively from the information
E:\FR\FM\12AUR1.SGM
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]]>Agencies
[Federal Register Volume 74, Number 154 (Wednesday, August 12, 2009)]
[Rules and Regulations]
[Pages 40482-40484]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-19249]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM399; Special Conditions No. 25-387-SC]
Special Conditions: Boeing Model 747-8/-8F Airplanes; Additional
Airframe Structural Design Requirements Related to Sudden Engine
Stoppage Due to Fan Blade Failures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for Boeing Model 747-8/-8F
airplanes. These airplanes will have a novel or unusual design
feature(s) associated with an increased engine size when compared to
previous model airplanes. These larger engines with larger bypass fans
are capable of producing higher and more complex dynamic loads than
previously experienced in older designs. 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: Effective Date: September 11, 2009.
FOR FURTHER INFORMATION CONTACT: Mark Freisthler, FAA, Airframe & Cabin
[[Page 40483]]
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 227-1119; facsimile (425) 227-1149.
SUPPLEMENTARY INFORMATION:
Background
On November 4, 2005, The Boeing Company, PO Box 3707, Seattle, WA,
98124, applied for an amendment to Type Certificate Number A20WE to
include the new Model 747-8 passenger airplane and the new Model 747-8F
freighter airplane. The Model 747-8 and the Model 747-8F are
derivatives of the 747-400 and the 747-400F, respectively. Both the
Model 747-8 and the Model 747-8F are four-engine jet transport
airplanes that will have a maximum takeoff weight of 970,000 pounds and
new General Electric GEnx-2B67 engines. The Model 747-8 will have two
flight crew and the capacity to carry 660 passengers. The Model 747-8F
will have two flight crew and a zero passenger capacity, although
Boeing has submitted a petition for exemption to allow the carriage of
supernumeraries.
Type Certification Basis
Under the provisions of Title 14 Code of Federal Regulations (14
CFR) 21.101, Boeing must show that the Model 747-8 and 747-8F airplanes
(hereafter referred to as the 747-8/-8F) as changed, continue to meet
the applicable provisions of 14 CFR part 25, as amended by Amendments
25-1 through 25-117, except for earlier amendments as agreed upon by
the FAA. These regulations will be incorporated into Type Certificate
No. A20WE after type certification approval of the 747-8/-8F.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 25) do not contain adequate or appropriate
safety standards for the 747-8/-8F because of a novel or unusual design
feature, special conditions are prescribed under the provisions of
Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the 747-8/-8F 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.
Special conditions, as defined in Sec. 11.19, are issued under
Sec. 11.38, and become part of the type certification basis under
Sec. 21.101.
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, the special conditions would also apply to the
other model under Sec. 21.101.
Novel or Unusual Design Features
The Boeing Model 747-8/-8F airplanes will incorporate the following
novel or unusual design features: High-bypass engines with a fan
diameter approximately twelve percent greater than those currently
installed on other Boeing Model 747 airplanes.
Discussion
High-bypass engines with a fan diameter approximately twelve
percent greater than those currently installed on other Boeing Model
747 airplanes, such as the 747-400 series, were not envisioned when
Sec. 25.361 was adopted in 1965. Section 25.361 addresses loads
imposed by engine seizure. Because of the higher inertia of the
rotating components, worst case engine seizure events become
increasingly more severe with increasing engine size.
Typically, the design torque loads associated with typical failure
scenarios have been estimated by the engine manufacturer. These loads
are used by the airframe manufacturer as limit loads. Section 25.305
requires that supporting structure be able to support limit loads
without detrimental permanent deformation, meaning that supporting
structure should remain serviceable after a limit load event. Limit
loads are expected to occur about once in the lifetime of any airplane.
For turbine engine installations, Sec. 25.361(b)(1) requires that the
engine mounts and supporting structures be designed to withstand a
``limit engine torque load imposed by sudden engine stoppage due to
malfunction or structural failure.''
Since Sec. 25.361(b)(1) was adopted the size, configuration, and
failure modes of turbine engines have changed significantly. Current
engines are much larger and are designed with large bypass fans. In the
failure event prescribed by Sec. 25.361 they produce much higher
transient loads on the engine mounts and supporting structure than
previous designs. At the same time, the likelihood of such an event
occurring in modern engines has become less. The service history of
modern turbine engines shows that engine seizures are rare events, much
less than what is typically expected for ``limit'' loads. While it is
important for the airplane to be able to support such rare loads safely
without failure, it is unrealistic to expect that no permanent
deformation will occur.
Given this situation, the Aviation Rulemaking Advisory Committee
(ARAC) has proposed a design standard for today's large engines. For
the commonly-occurring deceleration events, the proposed standard would
require engine mounts and structures to support maximum torques without
detrimental permanent deformation. For the rare-but-severe engine
seizure events such as loss of any fan, compressor, or turbine blade,
the proposed standard would require engine mounts and structures to
support maximum torques without failure, but allow for some deformation
in the structure.
The FAA concludes that modern large engines, including those on the
747-8/-8F, are novel and unusual compared to those envisioned when
Sec. 25.361(b)(1) was adopted and thus warrant special conditions.
These special conditions contain design criteria recommended by the
ARAC.
Discussion of Comments
Notice of proposed special conditions No. 25-09-02-SC for the
Boeing Model 747-8 and 747-8F airplanes was published in the Federal
Register on April 8, 2009 (74 FR 15888). No comments were received and
the special conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to
Boeing Model 747-8/-8F airplanes. 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 features, the special
conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
of the Boeing Model 747-8/-8F airplanes. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for the Boeing Model
[[Page 40484]]
747-8/-8F airplanes. The following special conditions are in lieu of
Sec. 25.361(b):
1. For turbine engine installations, the engine mounts, pylons and
supporting airframe primary structure (such as the affected wing and
fuselage primary structure) must be designed to withstand 1g level
flight loads acting simultaneously with the maximum torque load,
considered as limit load, imposed by each of the following:
(a) Sudden engine deceleration due to a malfunction which could
result in a temporary loss of power or thrust; and
(b) The maximum acceleration of the engine.
2. For auxiliary power unit installations, the power unit mounts
and supporting airframe primary structure (such as the affected
fuselage primary structure) must be designed to withstand 1g level
flight loads acting simultaneously with the maximum torque load,
considered as limit load, imposed by each of the following:
(a) Sudden auxiliary power unit deceleration due to malfunction or
structural failure; and
(b) The maximum acceleration of the power unit.
3. For turbine engine installations, the engine mounts, pylons and
supporting airframe primary structure (such as the affected wing and
fuselage primary structure) must be designed to withstand 1g flight
loads acting simultaneously with the transient dynamic loads,
considered as ultimate load, imposed by each of the following:
(a) Sudden engine stoppage due to the loss of any fan, compressor,
or turbine blade; and separately
(b) Where applicable to a specific engine design, any other engine
structural failure that results in higher loads.
4. The ultimate loads developed from the conditions specified in
paragraphs 3(a) and 3(b) are to be multiplied by a factor of 1.0 when
applied to engine mounts and pylons and multiplied by a factor of 1.25
when applied to the supporting airframe primary structure (such as the
affected wing and fuselage primary structure). In addition, the
airplane must be capable of continued safe flight considering the
aerodynamic effects on controllability due to any permanent deformation
that results from the conditions specified in paragraph 3, above.
Issued in Renton, Washington, on July 29, 2009.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E9-19249 Filed 8-11-09; 8:45 am]
BILLING CODE 4910-13-P
