The effects of low dissolved oxygen concentrations on fuel thermal sta
bility are far from being understood; however, such an understanding i
s essential for aircraft fuel system design. Experiments were conducte
d using a flowing system in which the dissolved oxygen level at the en
trance of the apparatus is varied. One of the most intriguing results
of these experiments is the increase in deposits in heated sections fo
r decreased oxygen consumption. This observation is seemingly contrary
to nearly all previous observations concerning the relation between d
eposit formation and oxygen consumption. For a given system, there app
ears to be a least favorable dissolved oxygen concentration which prod
uces the maximum amount of deposits. In addition, the deposition mecha
nisms in heated locations were quite different from those in cooled re
gions.