SECTION VII. HOW TO SAMPLE

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

taken place.

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

until needed.

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.