Samples may be taken earlier than the specified interval if adjustment to engine
sampling time is required to permit simultaneous engine sampling on multi-engine
aircraft. However, limits may not be exceeded to adjust sampling times.
Refer to the applicable scheduled maintenance or periodic inspection documents for
the specific routine sampling interval and specific sampling instructions for each
Type/Model/Series equipment being sampled.
Sampling Procedures. The success and effectiveness of the oil analysis program is dependent upon
reliable samples. A reliable sample is one, which is truly representative of the circulating fluid in the equipment
When to Take Samples. Samples should be taken as soon as possible after engine/equipment
shutdown and before any fluid is added to the system. An exception to this requirement is non-aeronautical
equipment oil samples. If fluid was not added following shutdown, these samples may be taken without warming a
component to operating temperature if the equipment has been operated within the last 30 days. If not operated
within the last 30 days, the equipment must be brought to operating temperature before sampling. (Army
personnel sampling nonaeronautical equipment should refer to DA Pam 738-750 for additional oil analysis
procedural information.) If a sample must be taken from a unit after new oil has been added, e.g., if oil level is too
low to permit sampling or if laboratory requests a special sample following oil addition and prior to equipment
operation, the old and new oils must be thoroughly mixed to obtain a homogeneous mixture by operating the unit
to operating temperatures before taking the sample. In systems where system oil temperature is not an operating
characteristic, a judgment of operating time required to obtain a homogeneous mixture must be made based
upon system characteristics such as system capacity, pump volume output, reservoir capacity, etc. These
procedures are necessary since any sample taken from a system in which the fluid is not a homogeneous mixture
will not be representative of actual fluid condition and may distort the laboratory trend for the equipment and may
result in a resample request from the laboratory.
Routine Samples. Routine sampling intervals shall be as specified in appropriate service
documentation governing operation and maintenance of each Type/Model/Series equipment. Cognizant Weapon
System/Model Engineering activities establish and maintain sample interval documentation to provide effective oil
(2) Special Samples. Special samples from equipment monitored by the service oil analysis
programs will be taken in accordance with the following guidelines:
Whenever requested by the laboratory.
Whenever directed by the unit maintenance activity to investigate suspected deficiencies.
(c) Immediately following an operation in which any abnormal condition or incident occurred
resulting from either malfunction of the oil lubricated system, or damage to the oil lubricated system from
excessive loss of engine oil, or low/fluctuating or zero oil pressure.
(d) Immediately prior to and after maintenance is performed affecting the oil lubricated system,
including the removal and replacement of an oil lubricated system component. Systems, which are sampled after
each flight, do not require samples taken prior to maintenance, provided an analysis was accomplished after the
last flight. The "after replacement" sample should be taken after ground/functional run-up or check flight.