Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and BD-500-1A11; Composite Wing and Fuel Tank Structure Post-Crash Fire Survivability, 63300-63302 [2014-25239]
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Federal Register / Vol. 79, No. 205 / Thursday, October 23, 2014 / Rules and Regulations
1. In the header of the document,
‘‘Notice No.’’ should have been ‘‘Special
Conditions No.’’
2. In one instance, one of the airplane
model numbers was published as ‘‘BD–
500–1A1’’ instead of ‘‘BD–500–1A11.’’
Correction
In Final special conditions document
(FR Doc. 2014–21789) published on
September 12, 2014 (79 FR 54574),
make the following corrections:
1. On page 54574, second column in
the header information, correct ‘‘Notice
No.’’ to read ‘‘Special Conditions No.’’
2. On page 54575, third column, last
line in the introductory text in the
section titled, ‘‘The Special
Conditions,’’ correct ‘‘BD–500–1A1’’ to
read ‘‘BD–500–1A11.’’
Issued in Renton, Washington, on October
16, 2014.
Michael Kaszycki,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. 2014–25241 Filed 10–22–14; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2014–0666; Special
Conditions No. 25–566–SC]
Special Conditions: Bombardier
Aerospace, Models BD–500–1A10 and
BD–500–1A11 Series Airplanes;
Isolation or Airplane Electronic System
Security Protection From Unauthorized
Internal Access
wreier-aviles on DSK5TPTVN1PROD with RULES
15:42 Oct 22, 2014
Jkt 235001
Issued in Renton, Washington, on October
16, 2014.
Michael Kaszycki,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. 2014–25240 Filed 10–22–14; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
14 CFR Part 25
This document corrects two
errors that appeared in Docket No.
FAA–2014–0666, Special Conditions
No. 25–566–SC, which was published in
the Federal Register on September 12,
2014 (79 FR 54572). There is an error in
the header information and in one
instance of one of the airplane model
numbers in the publication.
DATES: The effective date of this
correction is October 23, 2014.
FOR FURTHER INFORMATION CONTACT:
Varun Khanna, FAA, Airplane and
Flight Crew Interface Branch, ANM–
111, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind
Avenue SW., Renton, Washington
98057–3356; telephone (425) 227–1298;
facsimile (425) 227–1149.
VerDate Sep<11>2014
Correction
In Final special conditions document
(FR Doc. 2014–21788), published on
September 12, 2014 (79 FR 54572),
make the following corrections:
1. On page 54572, third column in the
header information, correct ‘‘Notice
No.’’ to read ‘‘Special Conditions No.’’
2. On page 54574, first column, last
line in the introductory text of the
section titled, ‘‘The Special
Conditions,’’ correct ‘‘BD–500–1A1’’ to
read ‘‘BD–500–1A11.’’
Federal Aviation Administration
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions;
corrections.
AGENCY:
SUMMARY:
On
September 12, 2014, the Federal
Register published document
designated as ‘‘Docket No. FAA–2014–
0666, Notice No. 25–566–SC,’’ (79 FR
54572). The document issued special
conditions pertaining to network
security in the digital systems
architecture, access from internal
sources, on the BD–500–1A10 and BD–
500–1A11 series airplanes.
As published, the document
contained two errors:
1. In the header of the document,
‘‘Notice No.’’ should have been ‘‘Special
Conditions No.’’
2. In one instance, the airplane model
number was published as ‘‘BD–500–
1A1’’ instead of ‘‘BD–500–1A11.’’
SUPPLEMENTARY INFORMATION:
[Docket No. FAA–2014–0434; Special
Conditions No. 25–544–SC]
Special Conditions: Bombardier
Aerospace, Models BD–500–1A10 and
BD–500–1A11; Composite Wing and
Fuel Tank Structure Post-Crash Fire
Survivability
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
These special conditions are
issued for the Bombardier Aerospace,
Models BD–500–1A10 and BD–500–
1A11 series airplanes. These airplanes
will have novel or unusual design
features when compared to the state of
technology envisioned in the
airworthiness standards for transport
category airplanes. These design
SUMMARY:
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features are composite materials used in
the construction of the fuel tank skin
and structure, which may behave
differently in a post-crash fire than
traditional aluminum construction.
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: This action is
effective on November 24, 2014.
FOR FURTHER INFORMATION CONTACT:
Alan Sinclair, FAA, Airframe and Cabin
Safety Branch, ANM–115 Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington 98057–3356;
telephone 425–227–2195; facsimile
425–227–1232.
SUPPLEMENTARY INFORMATION:
Background
On December 10, 2009, Bombardier
Aerospace applied for a type certificate
for their new Models BD–500–1A10 and
BD–500–1A11 series airplanes (hereafter
collectively referred to as ‘‘CSeries’’).
The CSeries airplanes are swept-wing
monoplanes with an aluminum alloy
fuselage sized for 5-abreast seating.
Passenger capacity is designated as 110
for the Model BD–500–1A10 and 125 for
the Model BD–500–1A11. Maximum
takeoff weight is 131,000 pounds for the
Model BD–500–1A10 and 144,000
pounds for the Model BD–500–1A11.
Conventional airplanes with
aluminum skin and structure provide a
well-understood level of safety during
post-crash fire scenarios with respect to
fuel tanks. This is based on service
history and extensive full-scale fire
testing. The CSeries airplanes will not
be fabricated primarily with aluminum
for the fuel tank structure. Instead, they
will be fabricated using predominantly
composite structure and skin for the
wings and fuel tanks. Composites may
or may not have the equivalent
capability of aluminum, and current
regulations do not provide objective
performance requirements for wing and
fuel tank structure with respect to postcrash fire safety. Because the use of
composite structure is novel and
unusual with respect to the designs
envisioned when the applicable
regulations were promulgated,
additional tests and analyses
substantiation will be required to show
that the CSeries airplanes will provide
an acceptable level of safety with
respect to the performance of the wings
and fuel tanks during an external fuelfed fire.
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Federal Register / Vol. 79, No. 205 / Thursday, October 23, 2014 / Rules and Regulations
Type Certification Basis
Under the provisions of Title 14, Code
of Federal Regulations (14 CFR) 21.17,
Bombardier Aerospace must show that
the CSeries airplanes meet the
applicable provisions of 14 CFR part 25
as amended by Amendments 25–1
through 25–129.
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 CSeries airplanes because of a
novel or unusual design feature, special
conditions are prescribed under the
provisions of § 21.16.
Special conditions are initially
applicable to the model for which they
are issued. Should the type certificate
for that model be amended later to
include any other model that
incorporates the same or similar novel
or unusual design feature, the special
conditions would also apply to the other
model under § 21.101.
In addition to the applicable
airworthiness regulations and special
conditions, the CSeries airplanes 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, and the
FAA must issue a finding of regulatory
adequacy under § 611 of Public Law 92–
574, the ‘‘Noise Control Act of 1972.’’
The FAA issues special conditions, as
defined in 14 CFR 11.19, in accordance
with § 11.38, and they become part of
the type-certification basis under
§ 21.17(a)(2).
Novel or Unusual Design Features
The CSeries airplanes will incorporate
the following novel or unusual design
features: The structural elements and
skin of the wings and fuel tanks will be
fabricated using predominantly
composite materials rather than
conventional aluminum.
wreier-aviles on DSK5TPTVN1PROD with RULES
Discussion
Transport category airplanes in
operation today have traditionally been
designed with aluminum materials.
Conventional airplanes with aluminum
skin and structure provide a wellunderstood level of safety during postcrash fires with respect to fuel tanks.
Current regulations were developed and
have evolved under the assumption that
wing construction would be of
aluminum materials.
Aluminum has the following
properties with respect to fuel tanks and
fuel-fed external fires:
• Aluminum is highly thermally
conductive and readily transmits the
heat of a fuel-fed external fire to fuel in
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15:42 Oct 22, 2014
Jkt 235001
the tank. This has the benefit of rapidly
driving the fuel tank ullage to exceed
the upper flammability limit of fuel
vapors prior to fuel tank skin burnthrough or heating of the wing upper
surface above the auto-ignition
temperature, thus greatly reducing the
threat of fuel tank explosion.
• Aluminum panels at thicknesses
previously used in wing lower surfaces
of large transport category airplanes
have been fire resistant as defined in 14
CFR 1.1 and Advisory Circular (AC) 20–
135, Powerplant Installation and
Propulsion System Component Fire
Protection Test Methods, Standards,
and Criteria.
• Heat absorption capacity of
aluminum and fuel prevent burnthrough or wing collapse for a time
interval that generally exceeds the
passenger evacuation time.
The ability of aluminum wing
surfaces to withstand post-crash fire
conditions when wetted by fuel on their
interior surface has been demonstrated
by tests conducted at the FAA Technical
Center. Results of these tests have
verified adequate dissipation of heat
across wetted aluminum fuel tank
surfaces so that localized hot spots do
not occur, thus minimizing the threat of
explosion. This inherent capability of
aluminum to dissipate heat also allows
the wing lower surface to retain its loadcarrying characteristics during a fuel-fed
ground fire and significantly delay wing
collapse or burn-through for a time
interval that usually exceeds evacuation
times. In addition, as an aluminum fuel
tank is heated with significant
quantities of fuel inside, fuel vapor
accumulates in the ullage space,
exceeding the upper flammability limit
relatively quickly and thus reducing the
threat of a fuel tank explosion prior to
fuel tank burn-through.
Fuel tanks constructed with
composite materials may or may not
have equivalent properties. AC 20–107B
(Change 1), Composite Aircraft
Structure, section 11b, ‘‘Fire Protection,
Flammability and Thermal Issues,’’
states: ‘‘Wing and fuselage applications
should consider the effects of composite
design and construction on the resulting
passenger safety in the event of in-flight
fires or emergency landing conditions,
which combine with subsequent egress
when a fuel-fed fire is possible.’’
Pertinent to the wing structure, postcrash fire passenger survivability is
dependent on the time available for
passenger evacuation prior to fuel tank
breach or structural failure. Structural
failure can be a result of degradation in
load-carrying capability in the upper or
lower wing surface caused by a fuel-fed
ground fire and also as a result of over-
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63301
pressurization caused by ignition of fuel
vapors in the fuel tank.
For the CSeries airplanes, composite
materials will be used to fabricate the
majority of the wing fuel tank. Hence,
the current regulations may not be
adequate for the certification of the
CSeries airplanes featuring wing fuel
tanks fabricated with composite
material. Therefore, Bombardier must
present additional confirmation by test
and analysis that the CSeries airplanes’
design provides an acceptable level of
safety with respect to the performance
of the wing fuel tanks when exposed to
the direct effects of post-crash ground
fire or under-wing fuel-fed fires.
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.
Discussion of Comments
Notice of proposed special conditions
No. 25–14–08–SC for the Bombardier
CSeries airplanes was published in the
Federal Register on July 16, 2014 (79 FR
41457). No comments were received,
and the special conditions are adopted
as proposed.
Applicability
As discussed above, these special
conditions are applicable to the Models
BD–500–1A10 and BD–500–1A11 series
airplanes. Should Bombardier
Aerospace apply at a later date for a
change to the type certificate to include
another model incorporating the same
novel or unusual design feature, the
special conditions would apply to that
model as well.
Conclusion
This action affects only certain novel
or unusual design features on two
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.
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 Bombardier
Aerospace Models BD–500–1A10 and
BD–500–1A11 series airplanes.
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63302
Federal Register / Vol. 79, No. 205 / Thursday, October 23, 2014 / Rules and Regulations
Composite Wing and Fuel Tank PostCrash Fire Survivability
1. The wing fuel tank structure must
withstand an external fuel-fed pool fire
for a minimum of 5 minutes.
2. The integrity of the wing fuel tank
structure must be demonstrated at:
• Minimum fuel load, not less than
reserve fuel level;
• Maximum fuel load equal to the
maximum range fuel quantity; and
• Any other critical fuel loads.
3. The demonstration must consider
fuel tank flammability, burn-through
resistance, wing structural strength
retention properties, and auto-ignition
threats from localized heating of
composite structure, fasteners, or any
other feature that may produce an
ignition source during a ground fire
event for the required time duration.
Issued in Renton, Washington, on October
16, 2014.
Michael Kascycki,
Acting Manager, Transport Airplane
Directorate.
[FR Doc. 2014–25239 Filed 10–22–14; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2014–0421; Special
Conditions No. 25–571–SC]
Special Conditions: Boeing
Commercial Airplanes, Model 767–2C
Airplane; Interaction of Fuel Systems
and Structures
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
These special conditions are
issued for the Boeing Model 767–2C
airplane. This airplane will have novel
or unusual design features when
compared to the state of technology
envisioned in the airworthiness
standards for transport category
airplanes. These design features include
the addition of four body fuel tanks and
a modified fuel management system
that, directly or as a result of failure or
malfunction, could affect the airplane’s
structural performance. The applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
for these design features. 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.
wreier-aviles on DSK5TPTVN1PROD with RULES
SUMMARY:
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15:42 Oct 22, 2014
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Effective Date: This action is
effective on November 24, 2014.
FOR FURTHER INFORMATION CONTACT:
Mark Freisthler, FAA, Airframe and
Cabin Safety Branch, ANM–115,
Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington 98057–3356;
telephone 425–227–1119; facsimile
425–227–1232.
SUPPLEMENTARY INFORMATION:
DATES:
Background
On January 18, 2010, Boeing
Commercial Airplanes applied for an
amendment to Type Certificate No.
A1NM to include the new Model 767–
2C. The Boeing Model 767–2C, which is
a derivative of the Model 767–200
currently approved under Type
Certificate No. A1NM, is a transport
category airplane, intended for use as a
freighter, powered by two PW4062
engines with a maximum takeoff weight
of 415,000 pounds.
The Boeing Model 767–2C will have
more fuel capacity than a traditional
freighter through the addition of four
body fuel tanks. The Model 767–2C
contains fuel systems that could,
directly or as a result of failure or
malfunction, affect the aircraft’s
structural performance. Current
regulations do not take into account
loads for the airplane due to the effects
of fuel system failures on structural
performance; therefore, special
conditions are needed.
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 or similar novel or
unusual design feature, the special
conditions would also apply to the other
model under § 21.101.
In addition to the applicable
airworthiness regulations and special
conditions, the Model 767–2C 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.
Type Certification Basis
Novel or Unusual Design Features
The Boeing Model 767–2C will
incorporate the following novel or
unusual design features: Fuel system
changes including the addition of
forward and aft body fuel tanks, a mainto-center-tank gravity transfer system,
hydraulically-powered-pumps for
jettison, a nitrogen generation system for
inerting of all fuel tanks, and a pressureregulating closed fuel tank vent system.
Digital electronic controls (i.e., fuel
management systems) are added for
control and monitoring of these systems.
Under the provisions of Title 14, Code
of Federal Regulations (14 CFR) 21.101,
Boeing must show that the Model 767–
2C meets the applicable provisions of 14
CFR part 25, as amended by
Amendments 25–0 through 25–130,
except for earlier amendments as agreed
upon by the FAA. These regulations
will be incorporated into Type
Certificate No. A1NM after type
certification approval of the Model 767–
2C.
In addition, the certification basis
includes other regulations, special
conditions, and exemptions that are not
relevant to these special conditions.
Type Certificate No. A1NM will be
updated to include a complete
description of the certification basis for
these model airplanes.
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 767–2C because of a novel
or unusual design feature, special
conditions are prescribed under the
provisions of § 21.16.
Discussion
The fuel management system is
designed to keep the fuel distributed in
accordance with fuel usage
requirements. System failures of these
new and modified systems may result in
adverse fuel distributions or center-ofgravity excursions that increase the
airplane loads. For example, a failure of
the main tank gravity drain valve may
result in less wing main tank fuel than
normal management; or failure of the
body auxiliary tank transfer systems
may result in excessive body fuel at
landing. Additionally, failures of the
nitrogen generation system, fuel transfer
system, or vent/pressure regulating
system may result in excessive fuel tank
pressures. These types of failures are
addressed by these special conditions.
Special conditions have been applied
on past airplane programs in order to
require consideration of the effects of
systems on structures. These special
conditions are similar to those
previously applied except that the scope
is limited to new fuel system features
unique to the Model 767–2C. These
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]]>Agencies
[Federal Register Volume 79, Number 205 (Thursday, October 23, 2014)]
[Rules and Regulations]
[Pages 63300-63302]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-25239]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2014-0434; Special Conditions No. 25-544-SC]
Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and
BD-500-1A11; Composite Wing and Fuel Tank Structure Post-Crash Fire
Survivability
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for the Bombardier
Aerospace, Models BD-500-1A10 and BD-500-1A11 series airplanes. These
airplanes will have novel or unusual design features when compared to
the state of technology envisioned in the airworthiness standards for
transport category airplanes. These design features are composite
materials used in the construction of the fuel tank skin and structure,
which may behave differently in a post-crash fire than traditional
aluminum construction. 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: This action is effective on November 24, 2014.
FOR FURTHER INFORMATION CONTACT: Alan Sinclair, FAA, Airframe and Cabin
Safety Branch, ANM-115 Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-2195; facsimile 425-227-1232.
SUPPLEMENTARY INFORMATION:
Background
On December 10, 2009, Bombardier Aerospace applied for a type
certificate for their new Models BD-500-1A10 and BD-500-1A11 series
airplanes (hereafter collectively referred to as ``CSeries''). The
CSeries airplanes are swept-wing monoplanes with an aluminum alloy
fuselage sized for 5-abreast seating. Passenger capacity is designated
as 110 for the Model BD-500-1A10 and 125 for the Model BD-500-1A11.
Maximum takeoff weight is 131,000 pounds for the Model BD-500-1A10 and
144,000 pounds for the Model BD-500-1A11.
Conventional airplanes with aluminum skin and structure provide a
well-understood level of safety during post-crash fire scenarios with
respect to fuel tanks. This is based on service history and extensive
full-scale fire testing. The CSeries airplanes will not be fabricated
primarily with aluminum for the fuel tank structure. Instead, they will
be fabricated using predominantly composite structure and skin for the
wings and fuel tanks. Composites may or may not have the equivalent
capability of aluminum, and current regulations do not provide
objective performance requirements for wing and fuel tank structure
with respect to post-crash fire safety. Because the use of composite
structure is novel and unusual with respect to the designs envisioned
when the applicable regulations were promulgated, additional tests and
analyses substantiation will be required to show that the CSeries
airplanes will provide an acceptable level of safety with respect to
the performance of the wings and fuel tanks during an external fuel-fed
fire.
[[Page 63301]]
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, Bombardier Aerospace must show that the CSeries airplanes
meet the applicable provisions of 14 CFR part 25 as amended by
Amendments 25-1 through 25-129.
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 CSeries airplanes because of a
novel or unusual design feature, special conditions are prescribed
under the provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the special conditions would also
apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the CSeries airplanes 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, and the FAA must issue a
finding of regulatory adequacy under Sec. 611 of Public Law 92-574,
the ``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type-
certification basis under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The CSeries airplanes will incorporate the following novel or
unusual design features: The structural elements and skin of the wings
and fuel tanks will be fabricated using predominantly composite
materials rather than conventional aluminum.
Discussion
Transport category airplanes in operation today have traditionally
been designed with aluminum materials. Conventional airplanes with
aluminum skin and structure provide a well-understood level of safety
during post-crash fires with respect to fuel tanks. Current regulations
were developed and have evolved under the assumption that wing
construction would be of aluminum materials.
Aluminum has the following properties with respect to fuel tanks
and fuel-fed external fires:
Aluminum is highly thermally conductive and readily
transmits the heat of a fuel-fed external fire to fuel in the tank.
This has the benefit of rapidly driving the fuel tank ullage to exceed
the upper flammability limit of fuel vapors prior to fuel tank skin
burn-through or heating of the wing upper surface above the auto-
ignition temperature, thus greatly reducing the threat of fuel tank
explosion.
Aluminum panels at thicknesses previously used in wing
lower surfaces of large transport category airplanes have been fire
resistant as defined in 14 CFR 1.1 and Advisory Circular (AC) 20-135,
Powerplant Installation and Propulsion System Component Fire Protection
Test Methods, Standards, and Criteria.
Heat absorption capacity of aluminum and fuel prevent
burn-through or wing collapse for a time interval that generally
exceeds the passenger evacuation time.
The ability of aluminum wing surfaces to withstand post-crash fire
conditions when wetted by fuel on their interior surface has been
demonstrated by tests conducted at the FAA Technical Center. Results of
these tests have verified adequate dissipation of heat across wetted
aluminum fuel tank surfaces so that localized hot spots do not occur,
thus minimizing the threat of explosion. This inherent capability of
aluminum to dissipate heat also allows the wing lower surface to retain
its load-carrying characteristics during a fuel-fed ground fire and
significantly delay wing collapse or burn-through for a time interval
that usually exceeds evacuation times. In addition, as an aluminum fuel
tank is heated with significant quantities of fuel inside, fuel vapor
accumulates in the ullage space, exceeding the upper flammability limit
relatively quickly and thus reducing the threat of a fuel tank
explosion prior to fuel tank burn-through.
Fuel tanks constructed with composite materials may or may not have
equivalent properties. AC 20-107B (Change 1), Composite Aircraft
Structure, section 11b, ``Fire Protection, Flammability and Thermal
Issues,'' states: ``Wing and fuselage applications should consider the
effects of composite design and construction on the resulting passenger
safety in the event of in-flight fires or emergency landing conditions,
which combine with subsequent egress when a fuel-fed fire is
possible.'' Pertinent to the wing structure, post-crash fire passenger
survivability is dependent on the time available for passenger
evacuation prior to fuel tank breach or structural failure. Structural
failure can be a result of degradation in load-carrying capability in
the upper or lower wing surface caused by a fuel-fed ground fire and
also as a result of over-pressurization caused by ignition of fuel
vapors in the fuel tank.
For the CSeries airplanes, composite materials will be used to
fabricate the majority of the wing fuel tank. Hence, the current
regulations may not be adequate for the certification of the CSeries
airplanes featuring wing fuel tanks fabricated with composite material.
Therefore, Bombardier must present additional confirmation by test and
analysis that the CSeries airplanes' design provides an acceptable
level of safety with respect to the performance of the wing fuel tanks
when exposed to the direct effects of post-crash ground fire or under-
wing fuel-fed fires.
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.
Discussion of Comments
Notice of proposed special conditions No. 25-14-08-SC for the
Bombardier CSeries airplanes was published in the Federal Register on
July 16, 2014 (79 FR 41457). No comments were received, and the special
conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Models BD-500-1A10 and BD-500-1A11 series airplanes. Should Bombardier
Aerospace apply at a later date for a change to the type certificate to
include another model incorporating the same novel or unusual design
feature, the special conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on two 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.
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 Bombardier Aerospace Models BD-500-
1A10 and BD-500-1A11 series airplanes.
[[Page 63302]]
Composite Wing and Fuel Tank Post-Crash Fire Survivability
1. The wing fuel tank structure must withstand an external fuel-fed
pool fire for a minimum of 5 minutes.
2. The integrity of the wing fuel tank structure must be
demonstrated at:
Minimum fuel load, not less than reserve fuel level;
Maximum fuel load equal to the maximum range fuel
quantity; and
Any other critical fuel loads.
3. The demonstration must consider fuel tank flammability, burn-
through resistance, wing structural strength retention properties, and
auto-ignition threats from localized heating of composite structure,
fasteners, or any other feature that may produce an ignition source
during a ground fire event for the required time duration.
Issued in Renton, Washington, on October 16, 2014.
Michael Kascycki,
Acting Manager, Transport Airplane Directorate.
[FR Doc. 2014-25239 Filed 10-22-14; 8:45 am]
BILLING CODE 4910-13-P
