every aircraft fueling hose must meet industry standard EI 1529/IOS (International Organization for Standardization) 1825 for hoses and assemblies. The hose must ini- tially be filled completely with the appropri- ate fuel and allowed to soak for at least eight hours. The fuel in the hose must then be disposed of properly and the hose refilled. To verify the absence of any manufac-
turing residue, you must perform an appearance check of the fuel for discolor- ation. The fuel should then be recirculated in an amount equaling at least twice the volume of the hose, back into storage, upstream of filtration. Follow up with a hose-end nozzle strainer inspection to con- firm the absence of any particulate contamination.
Lab Testing of Avgas and Jet Fuels In the case of avgas 100LL (aviation gaso- line 100 low lead), the critical aspects of
contamination are interfacial tension (how well water separates out from the fuel) and gum contamination, which leads to engine anomalies. The tests that should be per-
formed on avgas 100LL are: ■ ASTM D4176, appearance ■ ASTM D381, gum content ■ ASTM D1094, water reaction ■ ASTM D2887, simulated distillation (this
test is more sensitive to residue and chemical contamination than the stan- dard test for distillation, ASTM D86). The tests for aviation turbine fuels (also
known as jet fuels) are the same as those for avgas 100LL, with the addition of the
following: ■ ASTM D156, Saybolt color test ■ ASTM D3948, MSEP (microseparometer analysis, for water separation)
■ ASTM D2624, electrical conductivity ■ ASTM D3241, jet fuel thermal oxidation test (JFTOT)
■ ASTM D56, flash point.
The JFTOT is notable because it reveals
any change in volatility along with oxidation characteristics and evaluates insoluble and soluble materials that form deposits in the engine.
Correct Sampling Fuel sample preparation, handling, and follow-through are all key to successfully testing aviation fuel. If a jet fuel sample is drawn through sample points that incorpo- rate metals such as cadmium, brass, or copper, the JFTOT results may fail. Similarly, using galvanized piping (zinc) in avgas 100LL could alter the lab results. Finally, make sure the sampling point is clean and flushed before taking a sample. Accumulated solid particulate matter or any free water should be removed, and final fuel samples should be clear and bright. Use a 1 gallon, approved epoxy-lined sam- pling container, and flush and triple-rinse it with the fuel to be sampled and tested.
2020 Q4 ROTOR 65
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