FED-STD-791D
Method 5003.2
September 30, 1986
DEPOSIT-FORMING TENDENCIES OF AIRCRAFT TURBINE LUBRICANTS
1. SCOPE
1.1 This test method describes a procedure for determining the deposit and sludge
forming tendencies of aircraft gas turbine lubricants.
2. SUMMARY
2.1 A sample of the lubricant is circulated under controlled conditions for a
prescribed period of time through an aerated test chamber containing an aluminum tube
held at constant temperature. From the chamber the oil passes through a cooler, a line
filter, a circulating pump and back into the chamber. The weight of solid decomposition
products on the heated tube and on the line filter are determined. Changes in the
viscosity and neutralization number of the oil can be determined if desired.
3. SAMPLE SIZE
3.1 As needed.
4. REFERENCES, STANDARDS, AND APPARATUS
4.1 Deposition tester, Wright Air Development Center (Erdco Engineering Corp.,
Adison, IL) consisting of an oil circulation pump, coking head with tube, oil feeder, oil
cooler, line filter, and the necessary instrumentation and supporting structure (see Figure
1 through 5).
NOTE 1:
Model 1 is equipped with a pyrometer, Model 2 with a temperature
recorder, and Model 3 with a pyrometer, a selector switch, and a
differential pressure recorder. A "W" following the model number
indicates the inclusion of a watt-hour meter.
a. Cabinet. The test cabinet consists of a test section and an instrument section.
Ventilation and heat are provided to maintain the test section at 48.9 3C
(120 5F) and the instrument section at not more than 6C (10F) above room
temperature. The sections are separated by a partition.
b. Instrument section. The instruments and their locations are shown in Figure 1.
Optional items (differential-pressure recorder, watt-hour meter, pyrometer, and
selector switch) are included in this Figure.
c. Thermocouples. All thermocouples and leads are made from precision
calibrated iron constantan wire. Two bayonet thermocouples are provided for
the coking tube, one of which is connected to the stepless temperature control,
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