FED-STD-791D
6.7.2.4 After test, a rating of the interior test-oil sump wall and bottom is made. This
rating, which is not included in the calculation of the overall test rating, is reported in terms of
the type of surface deposits present and the area covered by each deposit rather than numerical
demerits.
6.8 Metal Specimen Preparation.
6.8.1 After test, the metal corrosion specimens are disassembled from the holder and
solvent-rinsed to remove residual test oil. (The specimens are stored in n-heptane if final
processing is delayed). The individual specimens are n-heptane swabbed using a series of cotton
swabs or pads until clean pads are noted. The coupons are then rinsed in clean n-heptane and
acetone, air-dried, and weighed to the nearest 0.1 mg.
6.8.2 Significant specimen weight change is reported in mg/cm2 ignoring edge areas in
the calculation of exposed surface area. A significant weight change is defined as a weight
variation of 0.20 mg/cm2 or more.
7. CALCULATIONS
7.1 This section is not applicable to the test procedure.
8. REPORTING
8.1 As required by the specification.
9. PRECISION
9.1 Precision data for this test is reported in AFAPL-TR-70-8, Volume I, Deposition and
Degradation Characteristics of Aircraft Turbine Engine Lubricants.
Copies are available through DDC (No. AD-871991).
Method prepared by:
Air Force-AFWAL/POSL - 1986
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