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 CASE POL 13 - Corroded Fuel Tank Bottom, R. Thomas
Trying to decide whether to replace a corroded fuel tank bottom.
Problem:
Symptom: 40 year and older fuel tanks with what appears to be a badly
corroded and pitted tank bottom with possible leaks.
Collection of Facts: An A/E had decided that the bottoms in several pre-WWII
fuel tanks were corroded to the point where the entire bottoms would have to
be replaced with new steel. A sight visit and ultrasonic inspection of the
bottoms revealed that the bottom plates were made from l/2" steel plate and a
hole saw cut indicated that all corrosion was occurring on the inside of the
tank and that the underside looked like new steel. Furthermore, corrosion was
limited to certain low point areas in the tank. The new tank bottom was to be
l/4" steel plate in accordance with latest standards (only l/2 as thick as 97%
of the old tank floor).
Solution: Even though some parts of the floor were badly pitted (some pits
were as much as 3/l6" deep), there was still more steel left than would be in
a brand new floor. All corrosion was interior, therefore, the isolated deep
pits were fill welded and new plates were welded over the corroded areas and
the edges ground smooth. The entire tank was then coated, producing a tank
better than new and at a fraction of the cost.
CASE POL 14 - MIL Specification Fueling Hose, R. Thomas
Failures with various MIL Specification fueling hoses.
Problem:
Symptom: Short life, blisters, bulges, cracks and pin holes are just some of
the problems experienced with several different MIL specification hoses.
Collection of Facts: For years, the Navy and Air Force have had difficulty in
obtaining a good aircraft refueling hose, even though we were buying NIL spec
hoses. The problems with the MIL specs seem to be that the manufacturer is
being told exactly how to construct his hose and, because of that he cannot
take advantage of new advancements in materials and fabrication methods. We
have now switched to referencing commercial API hose specifications. These
specs are performance oriented versus telling the manufacturer how to
construct the hose. The result has been dramatic and we are now getting
better fueling hoses.
Solution: Reference API 1529 for aircraft refueling hose, and you will get
the performance you want without telling a manufacturer how to construct his
hose.
CASE POL 15 - Petroleum Fuels/Energy, R. Thomas
Problem: Incorrect application of the shear-pin type emergency, dry breakaway
coupling on aircraft direct fueling pantograph stations.
Symptom: Ruptured aircraft fuel cells if breakaway is attempted with
incorrect type of breakaway coupling in place.
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