The inboard mounting of the brackets is pictured above. "A" is the main plate, and "B" is a 1/4" thick sub-plate
which picks up the two front cover bolts. A & B are held together with three AN-3 screws. Between them is a
60/1000" shim. This shim and the ability to drill the three holes in the field provides complete adjustability
to properly align and set the bracket, even if a builder introduces a variable like tall cylinders. We put a lot
of thought into the brackets to make them useful not just to us, but to all builders.
These brackets are an excellent example of how we develop parts. The process always follows this route:
4. After successful flight tests, set up the part for CNC production if possible in order to lower costs.
When this alternator bracket stands the test of time, it will join the ranks of our other flight tested
products available for sale.
Hundreds of people at Oshkosh studied our innovative fuel system for the 601/Corvair combination. The system
primarily runs on the Corvair's mechanical pump. The backup is an electric pump on continuous automatic standby.
Gus and I spent a tremendous amount of time to develop and test this setup, and I consider it fully proven.
We worked it out all the way down to the pre-flight checklist. Although at first glance it has a number of
components, its crucial characteristic is that it adds very little to the pilot's workload and does not require
the pilot to do anything should the primary pump malfunction. Additionally, it features a system to automatically
stop the electric pump in the event of an accident.
Although the system works quite well, and it would serve anyone who would choose to duplicate it, I'm currently
in pursuit of another system, one which would have an electric primary pump with a second electric as a backup.
Always in the forefront of my mind is the fact that our work is to serve amateur builders and non-professional
pilots. Our mechanical/electric system serves the recreational pilot well with its low workload, but I was
concerned that it requires some talent to construct, and the mechanical pump itself has initial maintenance
issues which cannot be ignored. With this in mind, we're pursuing the electric/electric combination. Remember,
only low wing airplanes without header tanks, like the 601XL, need fuel pumps. The vast majority of Corvair
powered airplanes are gravity feed.
Presented here is a technical discussion of the mechanical/electric system. I present it here to further
the greater understanding and learning of builders. We may yet use this configuration in another airframe, so
it's a good case to study. The picture above shows modifications we made to operate the stock mechanical pump.
The AN lines feature Earl's swivel ends, and XRP fittings. Also visible is the catch can, which would run a gas
leak overboard instead of allowing it to drip onto the engine.
Above is a view of the mechanical pump from behind. The pump we used in all of our flight testing is a Carter
M-3988 made by Federal Mogul. It is brand new and costs less than $45. You can also see that we've replaced the
screws with safety wired stainless Allens. The catch can and its white overflow tube is also visible here. The
full flow hose ends are 180 and 150 degree bends. The hose size is AN-6, and the thread on the pump is 1/8"
pipe. The only operating difficulty we had with the entire system in 75 flight hours was the need to retorque
the pump screws at two hours and again at 10 hours. We checked them at several other intervals. The new pump
crushed the gaskets slightly in operation, and needed the screws retightened to restore a good seal. If the
screws were allowed to get loose, the pump would drip into the catch can. After these two intervals, the screws
never again needed retorquing.
Testing aircraft fuel systems is very serious business. To give you an idea of the detail, we used a
micrometer to measure the length of the screws to ensure that screw stretching was not the cause of the loss
of the preload on the gaskets. In my years of testing, I have learned to be very cautious about attributing cause
to the first smoking gun you find. You have to be vigilant and seek out the real cause and effect, not just
the first likely one you stumble upon.
The firewall components of the mechanincal/electric fuel system are pictured above. Fuel comes through
the firewall at the lower left, goes throught the Andair GAS375-M gascolator (an excellent piece of equipment),
and goes into a Facet fuel pump. From there it goes up to the mechanical pump and returns under pressure to the
right hand side of the upper tier. The three fittings are, from right to left, sender for the Autometer fuel
pressure gauge, a Nason part number SM-2C-4F 4psi pressure switch, and an electric primer selonoid. In normal flight
operation, the engine runs on the mechanical pump alone. If pressure drops below 4psi, the switch automatically
turns on the electric pump. There is a manual override of this so the engine can be primed with the electric pump,
and there is a Nason 15psi switch in the oil system to prevent the pump from turning on without the presence of
15 pounds of oil pressure. We have it set this way to preclude the electric pump coming on should the engine and
mechanical pump stop in the event of an accident. The system is clever and relatively foolproof in operation.
It has a warning light in the instrument panel to tell you the electric pump is on. I like everything about the
system with the exception of the vigilance required on the initial installation of the mechanical pump.
Above is a view of the lower right hand side of the back of the engine. The white tube is the translucent
drain line from the catch can around the fuel pump. During the preflight, the electric pump can be turned on
in the override position. If there is a leak in the mechanical pump, you could either smell it or see it in
the overflow line. The coiled copper line is the primer. Our aircraft has an MA3-SPA carburetor with an
acclerator pump. It does not truly need a primer, however an electric primer is easy to install if you have
an electric backup pump. The line is coiled in this fashion, where it goes from the stationary motor mount to
the moving engine. Careful attention to detail like this makes for reliable operating engines. All instrumentation
and primer lines need to be carefully addressed to prevent any type of fatigue where they transfer from airframe
Pictured above are components of the oil system which we will flight test in the coming weeks. When we go
to an electric/electric fuel pump system, the stock oil filter housing of the accesory case will then only hold the oil filter
and bypass. We have built a blockoff plate to replace the stock oil filter housing, and have two AN-6 lines feeding a Permacool remote oil filter housing.
The oil filter is a high flow K&N 1004, which has an internal bypass and features a nut and safety wire hole
like a standard aircraft oil filter. It has an internal baffle that keeps it from leaking oil when it's
unscrewed. This will allow it to be mounted on top of the engine, without creating a mess at oil change time.
My plan is to relocate the filter to the top of the engine, behind the
starter. Relocating the filter and removing the mechanical pump will free up a tremendous amount of space on
the back of the motor. We currently have plenty of room, but I'm organizing the installation to eventually
allow the addition of a turbocharger. The 601 currently has a remote oil cooler and extensive oil temperature
instrumentation. The intention is to convert it to a block mounted, stock, 12-plate oil cooler. Simplicity is
the goal, even with turbocharging.
When the changes on the engine configuration are complete, we'll present complete installation photographs
on this site. If you have any questions, please feel free to call or write.