Ed:
I have advocated for many years that there is a serious problem with tha
architecture of the Alon fuel line routing.
The problem shows up if the fuel line is shut off at the base of the header
tank, and work is done on the remaining fuel system, or if the header tank is
drained for any reason or if all the fuel is consumed and it is refilled.
A basic fact of hollow lines is the fuel weight is enough to create a small
amount of fuel pressure at the carburetor, but this is not enough weight to
allow an air "bubble" to pass. A bubble of air in the fuel line will only
allow a limited amount of fuel to pass by, and will act as a partial
restriction, although THE LINE IS NOT RESTRICTED!!
This simple fact along with the fuel line routing to the Alon Gascolator setup
and beyond are the cause of many frustrating takeoff incidents, wherein the
equipment failure cannot be duplicated.
If you push down the tail of an Alon to duplicate the "Takeoff" angle of attack
and you have recently refilled your fuel system, an air bubble can occur
between the output of the header tank and the input to the carburetor. This
"Can" be duplicated by draining the header tank, and the loop in the fuel line
at the carburetor input, then refilling the fuel tank and powering up the
airplane, go through all the check lists, and taking off on a 3 mile long
runway, such as Castle, and see for youself. Halfway down the runway at an
altitude of 200 feet the engine will quit from fuel starvation! Plenty of room
remaining to land, but not so at a "Normal" airport.
Solution: Bleed the air from the fuel line connection to the carburetor by
disconnecting it and holding it to a position below the lowest point in the
fuel system till the fuel runs smoothly without air, and reconnect. following
all the safety procedures of course.
D. Wayne Woollard CPBE
o--iii---(
