During completion of routine fuel sampling, before the first
flight of the day, maintenance personnel reported finding a red/
brown liquid present in the fuel sample removed from the Boeing 737
aircraft. An inspection of the aircraft's fuel system was carried
out with no blockage of filters or other safety of flight issues
related to the contamination found.
Testing of the fuel recovered indicated no fungal (cladisporium
resinae) species. However, there was a heavy load of bacteria
(pseudomonas) present in the water layer, with a related film
between the water and fuel layers. The contamination was not
believed to be aircraft created but fuel source related. Operators
held meetings with fuel company representatives, CASA, and the ATSB
attempting to determine the origin of the contamination. Fuel
company representatives contacted their refineries but none
reported abnormal water drains. Mapping of the fuel supplied to the
aircraft reported as contaminated was completed by the operator
with no common fuel upload origin point defined.
Research identified several past similar events in Australia.
One such event in 1962 was experienced on Boeing 707 aircraft and
was believed related to sulphonates in the fuel combining with
trace levels of transition metals (including iron). Similar events,
reported in 1996 and 1997, were believed to have been caused by the
reaction of a complex of naphthenic/ sulphonic acids with
transition metals (including iron).
Despite intensive investigation of this event, the source of the
contamination could not be established and sporadic reports of
contaminated fuel samples persist. This contamination was not
related to the aviation gasoline (AVGAS) contamination reported in
December 1999, as analysis confirmed no presence of Ethylene
Diamine.