HOW TO SAMPLE
7-1. General. The success and effectiveness of the AOAP are dependent upon the testing and
analysis of reliable oil and grease samples. A reliable sample is one that is truly representative of
the lubricant oil in the component being evaluated. Special care is needed to ensure oil samples
are not contaminated, either by external dirt or other foreign material.
a. Samples taken from a component immediately after the addition of new lubricant will not
become representative of the oil system until complete mixing of the old and new lubricant has
b. The value of an oil sample is wholly dependent on whether the lubricant has circulated in
the component long enough to accumulate and mix wear metal concentrations uniformly.
c. Always take aircraft samples while a component is still warm. Samples shall be taken
within 15 minutes of an engine shutdown or aircraft landing. If a sample is to be taken from an
aircraft that is cold, run the system until it reaches normal operating temperature; then shut off
the system and sample it. If it is impossible to operate the system, as in the case of an aircraft
that is down for maintenance, indicate that the sample is a "cold" sample on the accompanying
DD Form 2026 and explain the circumstances.
d. Nonaeronautical equipment will be sampled under normal operating temperature
for a "hot" sample. This applies to both routine and special samples.
e. Store unused sampling supplies in a clean, closed container. Remove them only when you
are going to take a sample.
f. Avoid contamination of cut tubing and the inside of bottle caps by keeping them sealed
g. Use a new sampling tube to fill each sample bottle; discard tube after sampling.
h. Take the sample from approximately the same depth in the reservoir each time.
i. Do not use mouth suction to draw oil into a sampling tube.
j. To prevent contamination of the oil sample, avoid letting the sampling tube touch the sides
and bottom of the oil reservoir.
k. Take special precautions at all times to avoid dropping sampling equipment into oil
reservoirs since damage and failure may result.
7-2. Sampling Techniques.