Re: Do fuel valves ice jam due to water in fuel?

From:         Bob Falkiner <falkiner@interlog.com>
Organization: RJF Home
Date:         13 Sep 96 03:03:31 
References:   1 2 3
Followups:    1
Next article
View raw article
  or MIME structure

Patrick Roberts wrote:
>
> gerwocii@aol.com (GERWOCII) wrote:
>
> >It is my understanding that the fuel is heated. At what point this occurs
> >I do not know. If it is heated this would prevent and water condesation
> >from freezing.
>
> Most Jets I've worked on heat the fuel on the engine with a bleed air
> heat exchanger. Ussally just before the fuel contol unit.

it varies by the design.  usually fuel heaters are on the filter (engines
are certified up to 200 ppm water - a necessity when temperatures drop
from houston ambient to -56C at altitude as some condensation is
inevitable)

mil fuel has a de-icer glycol type compound added at 0.15 vol%.  some biz
jets are certified with de-icer which lowers the weight for heating
equipment.  others use fuel to cool avionics etc and pick up heat.

but in any case, there is no way to prevent some degree of condensation
with these kinds of temperature ranges - just different ways of dealing
with it.