By
GEORGE SAOUNATSOS
COPYRIGHT
2005, AVIATION FIRE JOURNAL / AIRBUS
Manuscript of the Article
published in
'Aviation Fire
Journal', March/April 2005
1. Introduction
The A380-800 is an all-new
twin-aisle, twin-deck four-engined aircraft having a baseline seating capacity
of 555 passengers in a three-class configuration. First flight is expected
in the first quarter of 2005, while it is scheduled to enter service with
Singapore Airlines in the second quarter of 2006. Total orders and commitments
to date (December '04) stand at 139 for both the passenger and freighter
versions as received from 13 airlines (122 passenger aircraft and 17 freighters).
The freighter version (A380-800F) is scheduled to enter service in 2008.
Although the payload capacity of the A380-800 in terms of seats is 35%
more than Boeing 747, it is only 7 feet longer having a total length of
238.6ft, while compared to the B777-300 and A340-600 it is actually 4 and
9 feet shorter respectively. Its total wingspan is 261.6ft.
2. Fire Safety
The progress made in aircraft
fire safety technology and the evolution of regulations over the past 35
years is noteworthy. This evolution, as illustrated below, contributes
to passenger confidence that today's commercial aircraft is safer than
ever.
Airbus' task as an aircraft manufacturer is to enhance the safety of the traveling public and the confidence of the aviation community by applying the highest safety standards to its products. The all-new A380 was an opportunity to apply state-of the-art technology that also has benefits in terms of fire safety.
In general, the fire safety standards set by Airbus for its aircraft, including the A380, not only meet but in most cases exceed the existing JAA and FAA requirements. For example, some of the stringent Airbus requirements with which the A380 complies include:
In addition, the A380
will comply with the new FAA 25.856 (a) & (b) requirements for "Flame
Propagation" (effective September 2005) and "Flame Penetration/Burn-through"
(effective September 2007). The A380 will inherently have better burn-through
characteristics on its upper fuselage due to the use of a new hybrid material
called GLARE – a sandwich of alternate layers of aluminum foils and unidirectional
glass fibres - which has considerably higher burn-through resistance than
conventional aluminum alloys. Hence, with the combination of GLARE on the
upper fuselage and insulation blankets on the inside lower fuselage, complying
with FAA 25.856(b), the A380 will be better protected against burn-through
during a post crash fuel fire.
The A380 incorporates several
Carbon Fibre Reinforced Plastic composites (CFRP) into primary and secondary
structures such as the central wing box, the tail cone, vertical and horizontal
stabilisers, etc.. It may not be widely known that CFRPs also have increased
burn-though resistance compared to conventional aluminum alloys, even if
the "resin" used for their manufacturing in aviation applications is responsible
for denser external smoke when the CFRP is exposed for a prolonged time
period to large fuel fires.
3. ARFF Operations
From the very early stages
of the A380’s development, Airbus established a team to manage all possible
airport compatibility issues including ARFF. The outcome of multiple studies
performed on many major international airports and their existing infrastructure
was fed back to the design parameters of the A380 in order to produce an
aircraft capable of safely operating from ICAO Code E or FAA Group V airports,
even though its corresponding airport design category is ICAO Code F or
FAA Group VI. As a result, the A380 has been designed to operate:
a) Under current ICAO ARFF
requirements,
b) With existing ARFF equipment
already in use at major airports and
c) According to established
ARFF practices
The A380 is classified under ICAO ARFF Category 10 due to its cabin width of 23.4ft. ICAO Cat. 10 calls for 8,500 gallons of minimum water/extinguishing agent on scene, which is 33% above ICAO Category 9 requirements (corresponding to B747) and 42% more than FAA Index E. We know that the methodology for determining minimum usable amounts of extinguishing agents (water) is based on the TCA/PCA principle developed more than 30 years ago, which is driven by fuselage length. Comparing, however, the minimum water requirements of the various ICAO ARFF categories, we see a certain logical pattern derived which relates to the quantity of fuel carried. For example, considering the revolution to commercial aircraft size during the 1970’s brought on by the B747 over the existing B707 and comparing the fuel quantities of these two aircraft, it becomes apparent that the increase in ARFF water requirements corresponds to the increase in the associated fuel quantities. A 103% fuel increase of B747 over B707 is analogous to the 101% increase in ARFF minimum water requirements between ARFF Categories 7 (B707) and Cat. 9 (B747). The same holds for the A380 and B747; a 29% fuel increase of the A380 over B747-400 is analogous to the 33% increase of minimum water requirements between ARFF Categories 9 and 10. It should also be noted that based on the current methodology for calculating minimum ARFF water quantities (ICAO Doc 9137 Part 1), the A380 has an actual requirement of 7,344 gallons of water, achieving a 14% margin with current minimum requirements of Cat. 10 (8,500 gallons). This is not the case for other wide body jets flying today, as some of them actually require more than the minima set by ICAO.
Although the full upper deck
existence might require some operating RFF procedures to be fine tuned,
the operational approach remains the same as with B747, while all ARFF
equipment already exists today for rescue operations on the upper deck.
The picture below depicts ARFF upper deck access vehicles used by Frankfurt
ARFF for B747 operations, while other portable stairs capable of reaching
8m height (same as B747 upper deck doors) are also illustrated.
Tests have also been carried out on fuselage piercing with "snozzle" ARFF equipment which confirmed that GLARE piercing for ARFF purposes is feasible with existing equipment, requiring 600psi compared to 500psi for conventional aluminum alloy panels (available "snozzle" vehicles may have as much as 2800psi piercing capability).
The emergency slides of the
A380 comply with the latest FAA TSO C69c requirements, and among others,
incorporate lighting on their vertical holds and at tip for night evacuation,
as well as "re-entry" lines for access of ARFF crews to both decks in case
of absence of other means (illustrated below). The slides extend 50.5ft
from the longitudinal centerline of the fuselage, which is only 3.2ft more
than B747 upper deck slides. The clearance obtained between the far end
toe of upper deck slides and the TCA perimeter is 10.5ft (aircraft at Maximum
Ramp Weight).
The A380 will have to meet
the 90 sec. evacuation time requirements at its highest density configuration
as per FAA/JAA 25.803. Furthermore, a separate "migration" scenario will
be run to investigate possible migration of upper deck passengers to main
deck, thus exceeding even the stringent certification requirements.
4. Conclusion
The A380 has been designed
to operate under existing ICAO ARFF requirements, according to current
practices and with existing equipment. After 35 years of development and
progress in commercial aviation safety, we can say that fire safety regulations
have evolved to cover all aspects of modern aircraft systems & evacuation
means, and the A380 design fully took account of that. For instance:
• Materials with improved
standards in terms of burn-though & fire propagation,
• Stricter requirements
which apply to aircraft manufacturing & certification and
• Airports, consulted throughout
by the Airbus teams, are better organized and equipped in terms of RFF
& crisis management to successfully address large aircraft operations.