Home' Asian Aviation : AAV May 2010 Contents Safety
More fuel-icing research
needed, crash investigators say
There is scant knowledge about the properties of ice formed in jet fuel and guidelines for fuel-system design
and testing need improvement, say investigators of the January 2008 crash of a British Airways Boeing 777.
Ian Goold looks beyond the headlines at the first Boeing 777 write-off.
The European Aviation Safety
Association (EASA) and US Federal
Aviation Administration (FAA)
should lead co ordinated research
into how ice forms in aviation
turbine fuel, and the properties of
such ice, to improve guidelines for aircra fuel-system
design and testing , say British safety o cials.
is is one conclusion of the UK Department for
Transport's Air Accidents Investigation Branch (AAIB),
in its report on the January 2008 accident to a British
Air ways (BA) Boeing 777-236ER (see Asian Aviation,
March 2010, page 6).
Investigators conclude that much current industry
guidance is based on research that was conducted before
1960. "Since that time, civil aircra have become larger,
y for longer periods, and incorporate new technolog y
and materials," they say.
Arriving at London Heathrow a er a 10.5-hour
ight from Beijing , China, the BA aircra came down
short of the runway when both Rolls-Royce RB211
Trent 895-17 engines lost power due to ice blocking the
fuel system. e risk from such icing is "complex", and
depends on inter-related circumstances that are not fully
understood, according to the AAIB.
Ice formation in jet-fuel systems from dissolved
and "entrained" water is well documented, but largely
based on 1950s' research obser vations and conclusions.
"Little is known about ice formed in [such] fuel," say
the investigators. Extensive tests during the accident
investigation obser ved "randomness" in the formation
of ice, with poor repeatability between batches of similar
Extensive testing and research was needed to determine
the most likely cause, with early indications suggesting
both engines had "rolled back", or lost thrust, due to
restricted fuel ow. e only physical evidence was
'cavitation' marks on the high-pressure (HP) pumps,
which made the investigation "particularly challenging ,"
according to the AAIB. Since the marks were fresh, they
"most probably" occurred on the accident ight a er the
restricted fuel ow led to low inlet pressure at the HP
e Boeing 777 was certi cated in the USA and
Europe in 1995, meeting contemporary airworthiness
requirements that aircraft and engine fuel systems
operate throughout their ow and pressure range, and
at low temperatures, with a prescribed concentration of
"Certi cation requirements did not [accommodate
the circumstances of this accident], as the risk was
unrecognised at that time," says the AAIB. Although
The British Airways accident in January 2008
was the first ever write-off of a Boeing 777.
Credit: Sam Chui
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