TABLE 2-6. VISCOSITY GUIDELINES FOR MIL-L-9000 AND MIL-L-2104 OILS AT 100 DEGREES F

NAVAIR 17-15-50.4

TM 38-301-4

T.O. 33-1-37-4

CGTO 33-1-37-4

TABLE 2-6. VISCOSITY GUIDELINES FOR MIL-L-9000 AND

MIL-L-2104 OILS AT 100 DEGREES F

ALLOWABLE USE LIMITS AT 100 DEG F

OIL SPECIFICATION

NAMETRY UNITS (Nm)

CENTISTOKES (cSt)

MIN

MAX

MIN

MAX

MIL-L-9000

183

100

225

MIL-L-2104:

GRADE 10

125

154

GRADE 30

156

192

GRADE 50

130

350

160

430

GRADE 15W40

117

144

Determine the wear-metal trend between the last sample and the current sample and compare with

the trend limit listed in the criteria table. Most abnormal trends are usually readily apparent. The trends in the

table are based on the wear-metal between samples will not be exactly the specified hours; therefore, a

conversion must be made for approximate trend value comparison purposes. A trend comparison can be made

by dividing the wear-metal increases between samples by the operating hours between samples and then

multiplying the results by 10. Trend values for the specified sample intervals are calculated as follows:

A-B x

10 = trend value for 10 hours

C-D

A = PPM this sample

B = PPM last sample

C = operating hours this sample

D = operating hours last sample

NOTE

The formula shown above for calculating trends is a quick way to determine the trend

values. However, trend values calculated using this formula for samples taken very

frequently may be much less accurate or reliable than trend values calculated for

samples taken less frequently. This possibility of error is caused by the spectrometer

allowable tolerances and also by the possibility of a variance in the rate of wear-metal

production over a period of time. The calculated trend values will be helpful information

for the evaluation process, but if samples taken more frequently than at 10 hour

intervals are being evaluated, the calculated trend values are not considered accurate

for use as equipment acceptable/not acceptable criteria.

Wear-metal concentrations exceeding the guidelines but with normal trends may, in some cases, be

acceptable, although samples may be required more frequently to minimize the possibility of missing an

impending failure.

2-13