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Fuel System Description
The Meyers fuel system has proven extremely reliable over the years without many of the problems associated with systems of similar vintage. As our aircraft age, there are several areas that need to be checked and serviced. The exact service instructions will be covered in a Service Information Letter to be issued in the near future. To allow field trouble shooting and repair, the following system history and description may be helpful.
The 200 started its certification journey with an O-470 engine. The fuel system did not need return lines for this carbureted engine. Before the completion of the initial certification, the decision was made to change to the IO-470. This fuel injected engine necessitated a complete redesign of the fuel system to include fuel return lines from the engine driven pump to the fuel tanks.
Rather than create a system that was overly complicated, such as the Cessna twin system which puts the return fuel from the aux tanks back into the main tanks, Meyers decided to put more effort into the design of the selector valve so that the fuel would always be returned into the tank that was selected as the feed tank. This necessitated a very precision and custom made valve which had two independent halves, operated by a single lever with a common shaft between the halves. This excellent and ingenious design has served us well for over 40 years.
Below is a picture of a disassembled valve showing its complexity and the number of components. There are 12 o-ring seals, eight delrin sliders and various springs, washers and roll pins.
The fuel output is at the bottom end of the selector valve. From there it goes to the fuel strainer. At the output of the fuel strainer, there is a Tee fitting with one side of the Tee going to the input of the electric fuel pump and the other going to a check valve. The check valve is attached to another Tee fitting where the output from the electric pump joins the main fuel feed to the engine driven fuel pump. The check valve prevents pressure from the electric pump from going backwards, away from the engine.
The return from the engine driven fuel pump goes through the firewall into a flex hose, then a 304 stainless 1/4" line with a 90 deg inboard bend going toward the top of the fuel selector. After the bend, there is another check valve before the 90 deg fitting that goes into the top of the fuel selector valve. This whole three piece assembly, 304 stainless line, check valve and flex line, should be covered with a 3/4" piece of black vynal (sic) tubing that is clamped at the firewall fitting and whose aft end is unclamped so that any seepage will drain into the selector valve drip pan.
To complete the system, each tank has a fuel supply line going to the valve and a fuel return line coming from the valve that are both selected by turning the fuel selector valve to the appropriate position.
Return to Fuel System Schematic
Paul M. Whetstone, President
Email pwhetstone@meyersaircraft.com
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