Fuel Systems

Appendix A — Fuel System Standard

15.0 — Lab Examination No. 11
Fuel System Static Pressure Test cont'd

15.5.8 Connect either an air or GN2 pressure source capable of supplying a regulated pressure of 0–10-psig to the pressure supply adapter in the fill hose. A pressure gauge or a manometer shall be connected to a tee in the pressure supply line as close as possible to the pressure supply adapter. A pressure gauge shall have a range not exceeding three times the test pressure as required by paragraph 15.5.7. The relief valve shall be set at 1.5 ±0.5-psi above the test pressure as required by Paragraph 15.5.7.

FIGURE: Procedure — Test Schematic

15.5.9 Verify that the system is configured similar to the Test Schematic and is ready for testing:

a. Pressure supply valve closed.
b. Pressure supply regulator fully decreased (ccw).
c. Fuel shutoff valve between main tank and any auxiliary tank full open (if any).
d. Any valve between the main tank and the carburetor full open (if any).

15.5.10 Open the pressure supply valve. Slowly increase the pressure supplied to the system by turning the regulator cw for monitoring the pressure gauge or manometer. Increase the pressure at a rate not to exceed 1/2-psi per minute until the required test pressure is reached as determined by Paragraph 15.5.7 and indicated on the pressure supply gauge or the manometer.

15.5.11 Maintain this test pressure ±1/4-psi for at least 5 minutes and allow the system to stabilize. During this period verify that there is no audible leakage in the system.

Note:
At any time during the test when leakage is detected, the points of leakage should be noted and documented, and the system should be vented to 0-psig. If the leakage is due entirely to the test hardware, the leak shall be corrected and the test rerun starting with Paragraph 15.5.9. If the leakage is in the fuel system and determined to be caused solely by the improper installation of a component as determined by the test engineer (such as a hose clamp left off or a loose B-nut), the installation may be corrected to the proper specification and the test rerun starting with Paragraph 15.5.9. Any discrepancies shall be so documented in the procedure.

15.5.12 Verify that the entire fuel system has been pressurized as evidenced by the pressure gauge readings at the auxiliary fuel tank, if installed, and at the engine fuel inlet. These gauges will not necessarily indicate much less than the pressure as the pressure supply gauge and there is no requirement for them to do so. The engine fuel inlet pressure gauge may indicate much less than the pressure supply gauge, depending on the anti-siphon valve installed and the other components in the fuel feed line. Any positive indication of pressure is acceptable. If 0-psig is indicated, the test shall be halted until the situation has been examined, and the proper corrective action is determined by the test engineer.

15.5.13 With the pressure supply gauge indicating the required test pressure ±1/4-psi and stable, close the pressure supply valve and record the pressure indicated. This is the initial pressure decay reading.

15.5.14 Observe the pressure supply gauge or manometer for a period of five minutes for tanks whose fuel capacity is 50-gal. (189.3 l) or less. For tanks over 50-gal. (189.3 l), an additional minute shall be added to the five minutes for each 10-gal. (37.9 l) increment or fraction thereof.

Example:
A 61-gal. (230.9 l) tank, or a 70-gal. (265 l), tank shall be observed for seven (7) minutes.

At the end of the required time, record the pressure indicated on the pressure supply gauge. This is the final reading. The pressure reading shall have decreased from the initial pressure reading less than 1/4-psi if a pressure gauge was used or less than 0.5 in. (1.3 cm) if an Hg manometer was used.

15.5.15 If the system pressure has decayed more than allowed from the initial pressure reading, verify no leakage exists in the test hardware using a leak detection solution and reject the fuel system if required by Paragraph 15.5.11. Otherwise, correct the problem and rerun the test starting with Paragraph 15.5.13. Document any discrepancy.

15.5.16 Perform a complete leak test of the entire fuel system using a leak detection solution. The test shall include:

a. fuel tank(s) and vent connections except at the hull or deck fitting(s)
b. fuel tank(s) fuel indicator fitting
c. fuel tank(s) feed line connection
d. any other connection or fitting on the fuel tank(s)
e. feed line between main tank and auxiliary tank, if installed, and any valves or
components including connections and fittings
f. feed line between main tank and the carburetor and any valves or components such as anti-siphon valve, shutoff valve, fuel fittings and/or strainer, fuel pump including connections and fittings
g. any other line or component which is part of the fuel systems

No leakage in the system is allowed. If leakage is detected, the fuel system shall be rejected. If no leakage is detected, the fuel system shall be deemed acceptable according to the requirements of this procedure. Record whether or not any leakage was found and the location(s).

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