Two Rules of Hose Installation that are often Violated when Installing Aircraft Fuel Flow Transducers
1. Fittings should not be used as a bracket.
The fitting should not see any forces (from the overhang weight of the transducer or movement or vibration). A hose should be installed with a slight loop or radius to absorb any movement or thermal expansion or contraction. Some suggest using steel fittings instead of the traditional aluminum AN fittings because they are stronger. If you intend to use the fitting as a bracket then yes, by all means use steel. If you intent to use the fitting as a fitting then steel just adds weight. A copper-based alloy fitting is the ideal fitting to use in aluminum bosses; as a substitute, aluminum.
2. A hose should have a loop or radius. It should not stretch straight from fitting-to-fitting.
A short straight hose is a rigid connection. Any thermal expansion, contraction; movement is transfered to the fitting, thereby violating rule #1 above.
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