How do I keep contaminants out of my fuel system?

The fuel selector valve works in unscreened fuel. Contaminated fuel can cause selector valve seal damage. When fueling from possibly contaminated fuel sources McFarlane recommends the use of a fuel filter, such as Mr. Funnel or another filtering device, to reduce trash in the fuel system.

What pressure is used to test the fuel selector valves after repairs?

We pressure test our repaired valves to a minimum of 5 psi using precision controlled air pressure and a calibrated low pressure indicator. This pressure is above the normal fuel pressure on the valve and below the limits of the springs in the valve. Each valve is submerged in Stoddard solvent while the air pressure is applied to the valve. The valves are then tested in each position to assure that there are no inter-port or external leaks. Leaks are detected by looking for air bubbles escaping from the valve.

How do I know when to replace or service my fuel selector valve?

The most common indication of external fuel valve leaks is the smell of avgas in the cabin. Most valves are located under the cabin floor. Fuel stain on the valve and drain plug or drain valve or on the belly of the aircraft can also indicate external leakage. External leaks are generally around the actuation valve stem. Internal leaks are detected when the fuel is turned off and fuel continues to drip during fuel system maintenance. Inner port leakage will allow fuel from one tank to leak into another fuel tank. This type leak is difficult to detect. Fuel transfer from one tank to another with the fuel valve selected to one tank only will indicate inner-port leakage. An extended period of time is needed to detect fuel transfer from one tank to another. Generally if internal leakage is detected when servicing the fuel system, it is likely there is also inner-port leakage.

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Home / Shop Parts ... / FSS-KT-21

P/N: FSS-KT-21

Name: FUEL SLCTR VALVE O-RING & GSKT KIT
Brand: McFarlane Aviation
SKU: FSS-KT-21
Price: 54.26 USD
Availability: InStock

FUEL SLCTR VALVE O-RING & GSKT KIT

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Approval	Kit with Approved Contents
Condition	New
Manufacturer	McFarlane Aviation
Dimensions	L: 7 x W: 6 x H: 0.5 in
Weight	0.0375 lbs
Unit of Measure	Each
Retail Price	$57.29
Your Price	$54.26
Stock Status	Expected ship date is 09-23-2026. (typically ships in 1-3 business days)

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OEM Part Number	McFarlane Part Number	Comment
FSSG-KT-1	FSS-KT-21	Verify eligibility to determine the correct kit.

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Seal Kits

Only McFarlane has FAA approval to replace the old, less fuel resistant o-rings with the latest fuel-proof fluorocarbon o-rings!

Conveniently packaged to include all of the necessary o-rings and/or gaskets applicable to specific single engine Cessna aircraft models. McFarlane replaces the old Buna-N or Nitrile (MS series) o-rings and early synthetic rubber (NAS series) o-rings with fluorocarbon elastomer, which has improved fuel and heat resistance. Cork/rubber gaskets meet tough government standards for fuel resistance.

WARNING: Cancer and/or Reproductive Harm - www.P65warnings.ca.gov