MIL-PRF-23699 Lubricating Oil, Aircraft Turbine Engine, Synthetic Base, Nato Code Numbers: O-152, O-154, O-156, And O-167This specification covers four classes of gas turbine engine lubricating oils, primarily used for aircraft engines, which have a nominal viscosity of 5 centistokes at 100 ┬░C and which are typically made with neopentyl polyol ester base stocks. This oil is identified by NATO Code Numbers O-152, O-154, O-156, and O-167.

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MIL-PRF-23699G

The post-test sludge content shall be determined as follows:

g. Decant oil from the test tube through a preweighed l0.0 micron

polytetrafluouroethylene filter (Militec LCWP 047-00 or equivalent) and measure

filtrate volume.

h. Set filtrate aside for viscosity and acid number tests.

i. Remove all sludge from test equipment with rubber policeman, wash equipment and

filtered sludge with petroleum ether, oven dry sludge sample, and weigh and compute

sludge weight per 100 mL of oil.

j. Do not add the petroleum ether washings to the oil filtrate used for viscosity and acid

number. Petroleum ether, with a boiling range of 30 to 60 �C, n-heptane, or hexane

shall be used in place of 1,1,1-trichloroethane (O-T-620).

4.4.13 Gear load carrying ability. The average of six determinations for STD, C/I, and HTS

classes of oil shall be not less than 102 percent of the reference oil (Hercolube A, see 4.4.13.1)

when tested in accordance with FED-STD-791, method 6508 and table II. The average of six

determinations for EE class of oil shall not be less than 110 percent of the reference oil. All six

determinations shall be made on the same machine. The reference oil average rating used to

obtain the relative ratings shall also be reported. Only the Ryder gear machines having a

reference oil average rating of 2,100-2,600 lb/in. after eight determinations are acceptable.

4.4.13.1 Source for standard reference oil for Ryder Gear Test (table II). Standard

reference oil may be obtained from the Naval Air Systems Command, AIR 4.4.2.2, Propulsion

Lubricants Team, 22229 Elmer Road, Building 2360, Unit 4, Patuxent River, MD 20670-1534.

4.4.14 Bearing deposits.

a. Post test oil viscosity sample is compared with viscosity of new oil samples tested at

40 �C. Post test oil total acid number is compared to the total acid number of the new oil

sample. The viscosity shall be determined in accordance with ASTM D445. The total

acid number shall be determined in accordance with SAE ARP5088.

4.4.14.1 Classes STD and C/I. The qualification sample will be evaluated in a 100 hour test

in accordance with table II (FED-STD-791, Method 3410, severity level 1-1/2).

4.4.14.2 Classes HTS and EE. The qualification sample will be evaluated in a 200 hour

test in accordance with table II (FED-STD-791, Method 3410, severity level 1-1/2).

4.4.15 Minisimulator test. The enhanced ester qualification sample after a 100-hour

minisimulator test (SAE ARP6166) shall perform in accordance with table II.

a. Post test oil viscosity sample is compared with viscosity of new oil samples tested at

40 �C. Post test oil total acid number is compared to the total acid number of the new