MIL-PRF-87260B(USAF)
a. Place the specimen in an environmental chamber hung from an insulation support with
a volume resistance greater than 1 x 1016 ohms.
b. Attach the voltage lead to the specimen using a stainless steel clamp with a minimum
surface area of 2 inches square on each side of the specimen.
c. Place the non-contact voltmeter within 3/8 to 1/2 inch of the specimen at least 8
inches from the clamp.
d.
Allow test chamber to condition samples for a minimum of 24 hours at test conditions.
e.
Apply the voltage to the foam using the static generator.
f. Monitor the voltage on the non-contact voltmeter, when 5000 volts is achieved,
remove the voltage source and apply a ground to the clamp.
g. Measure the time required for the voltage to dissipate from 5000 volts to 500 volts. A
chart recorder connected to the external output of the non-contact voltmeter can be used to
accurately measure the dissipation time.
4.5.27.4 Report.
Report sample designation (run or lot number), conditioning time, charge cutoff, and three static
decay results for each polarity (plus or minus), for each specimen at each designated
temperature. In addition, report test temperature/humidity, decay voltage and charging voltage,
dissipation time, and test equipment details. Data shall be reported for each designated test
condition.
4.5.28 Aircraft service test evaluation.
A full scale aircraft service test evaluation of the electrically conductive material shall be
conducted for a minimum of 6 months prior to approval of a material for the Qualified Products
List (QPL). The test shall be conducted under controlled conditions and samples of the product
shall be removed from the aircraft fuel system for evaluation of critical properties. These critical
properties shall include, but shall not be limited to, electrical resistivity, tensile strength,
contamination, and compression load deflection. The installation shall include, as a minimum,
one complete fuel tank on a given aircraft, and should preferably include the entire fuel tankage.
Test samples (various foam kit pieces) of the product shall be identified in several fuel tank
locations and tested for initial electrical resistivity (through the piece thickness) prior to fuel tank
installation. The selected foam kit pieces will be removed at 3 to 6-month intervals depending
on the service test duration. Additional foam kit pieces shall also be provided to replace those
pieces that are removed for critical property testing. The material vendor shall conduct
laboratory evaluations of the test specimens if requested. A detailed service test plan shall also
be provided to the qualifying activity for approval prior to initiation of the service evaluation. If
possible the testing should be conducted in a severe (cold) climate where electrostatic
generation, discharges, ignitions were prevalent with blue polyether foam. Consideration
should also be given to demonstrating over-the-wing (gravity) refueling if available on the
aircraft. Guidelines for designing a foam kit for use in fuel tanks are provided in SAE AIR-4170.
4.6 Inspection of preparation for delivery.
Inspection of the preservation, packaging, packing, and marking for shipment shall be in
accordance with the requirements of section 5.
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