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Special Conditions: Boeing Model 787-8 Airplane; Composite Fuselage In-Flight Fire/Flammability Resistance
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Boeing must prove 787 materials halt flames, are not toxic John Croft, WashingtonDC(26Apr07, 17:32 GMT, 275 words)
US FAA wants Boeing to prove that the composite structures of the 787 will not propagate fires that may develop in inaccessible areas and that fumes from composites and any nearby thermal/acoustic insulation will not be toxic to passengers.
The special certification conditions, published today, are a result of the FAA'sinexperience with large scale use of new structures on an aircraft.
The 787's wing, fuselage skin, stringers, spars and "most other structural elements of all major subassemblies of the airplane" are composite, according to the FAA. As such, the agency says the fuselage "cannot be assumed to have the fire resistance previously afforded by aluminium".
There are currently no standards for in-flight fire propagation with respect to an aluminium fuselage, says the FAA, as past investigations have shown that thin film covering the thermal/acoustic insulation, not the aluminium structure itself, has allowed fires to spread.
Those fires were typically caused by electrical issues, either short circuits, arcing caused by chafed wiring or ruptured ballast cases. The FAA addressed the insulation by publishing a rule in 2003 requiring that the material be tested to more stringent flame propagation requirements.
With the 787 and its "extensive use of new construction material" however, the FAA now says the fuselage itself "cannot be assumed to have the fire resistance previously afforded by aluminium".
Under the proposal, Boeing will have to show the 787 will provide the equivalent level of in-flight survivability as a conventional aluminium fuselage airplane, including resistance to flame propagation by both the structure and thermal/acoustic insulation.
Further, the FAA says "all products of combustion that may result must be evaluated for toxicity and found acceptable".
Click here for story.
_________
Boeing must prove 787 materials halt flames, are not toxic John Croft, WashingtonDC(26Apr07, 17:32 GMT, 275 words)
US FAA wants Boeing to prove that the composite structures of the 787 will not propagate fires that may develop in inaccessible areas and that fumes from composites and any nearby thermal/acoustic insulation will not be toxic to passengers.
The special certification conditions, published today, are a result of the FAA'sinexperience with large scale use of new structures on an aircraft.
The 787's wing, fuselage skin, stringers, spars and "most other structural elements of all major subassemblies of the airplane" are composite, according to the FAA. As such, the agency says the fuselage "cannot be assumed to have the fire resistance previously afforded by aluminium".
There are currently no standards for in-flight fire propagation with respect to an aluminium fuselage, says the FAA, as past investigations have shown that thin film covering the thermal/acoustic insulation, not the aluminium structure itself, has allowed fires to spread.
Those fires were typically caused by electrical issues, either short circuits, arcing caused by chafed wiring or ruptured ballast cases. The FAA addressed the insulation by publishing a rule in 2003 requiring that the material be tested to more stringent flame propagation requirements.
With the 787 and its "extensive use of new construction material" however, the FAA now says the fuselage itself "cannot be assumed to have the fire resistance previously afforded by aluminium".
Under the proposal, Boeing will have to show the 787 will provide the equivalent level of in-flight survivability as a conventional aluminium fuselage airplane, including resistance to flame propagation by both the structure and thermal/acoustic insulation.
Further, the FAA says "all products of combustion that may result must be evaluated for toxicity and found acceptable".
