SERVICE LETTER #22
Header Tank and Fuel Line Routing
All Kitfox™ Builders and Owners (using a header tank)
SkyStar Aircraft Corporation
keeping with SkyStar Aircraft policy of informing our customers of
important technical information, this Service Letter is being issued
as an advisory which needs your attention. While advising in nature,
the subject of this letter should be considered carefully and a
Service Bulletin will be issued in the near future with specific
instructions regarding maintenance action you will need to perform.
has received reports of header tanks being drained and not refilling
(potentially causing fuel starvation), while there is still plenty of
fuel in the wing tanks. This has occurred in aircraft with both front
and rear mounted header tanks.
have been able to recreate this fuel starvation in a special test rig.
In our test the fuel lines were routed out of the wing tanks to the
valve on the head rack, then across to the opposite side, down and
back to the rear mounted header tank, or down under the door, forward
to the firewall and up to the front mounted header tank. In each
situation the header tank was vented and only one wing tank valve
was turned to the “on” position. (It is feasible that this
situation could occur with both wing tank valves turned on). The fuel
flow to the header tank from the wing tank stopped when the wing tank
was un-ported (as in a “slip” with low fuel) and did not resume
because of the air introduced into the fuel line.
testing has shown that when the fuel line is routed directly forward
out from the wing tank, above the door, then down along the diagonal
brace to the front mounted header tank, or out of the tank and
directly back to the rear mounted header tank, fuel flow would resume
on its own to the header
tank from the wing tank after un-porting.
Kitfox's with the standard nose tank and wing tanks should be aware of
this situation, but because of the fuel’s visibility in the standard
nose tank there should be little possibility of fuel starvation.
further testing, each Kitfox™ owner with a rear or front mounted
header tank should (in the best interest of safety) take the following
Service Letter will be followed-up by a detailed Service Bulletin
containing information and recommendations, when testing is completed.
you have any questions concerning this Bulletin or procedures, please
feel free to call our Technical Support Dept. at (208) 466-1711.