JOAP ATOMIC EMISSION ROTRODE

NAVAIR 17-15-50.3

TM 38-301-3

T.O. 33-1-37-3

CGTO 33-1-37-3

ENGINE:

J69-T-25/-25A

AIRCRAFT:

(T-37)

JOAP ATOMIC EMISSION ROTRODE

Abnormal Trend

(PPM Increase

in 10 hrs)*

Normal Range

0-8

0-1

0-7

0-2

Marginal Range

9-15

1-2

2-3

1-2

8-9

3-8

High Range

16-40

3-9

4-14

3-18

10-11

9-14

Abnormal

41+

10+

15+

19+

12+

15+

Average Concentration Other Elements:

Ni=1

Pb=13

Si=5

Sn=8

Ti=1

Mo=1

If the calculated PPM trend value is equal to or greater than the trend PPM value limit, the engine has an

abnormal trend.

Any T-37 oil sample that flames up in the oil analysis spectrometer will prompt the JOAP lab to place the engine

on code T (tear down). Fuel contamination of the oil will be reported to responsible activity when detected. Fe is

principal wear metal. Gradual increase in Fe near or to the abnormal value over a long period of time (several

hundred flying hours) is sometimes indicative of rotational movement of the No. 2 bearing. This rotational

movement, or creep, characteristic is normal and is a design feature of the No. 2 bearing. Rapid increases in Fe

are sometimes indicative of accessory drive gear shaft nut backing off because of a sheared tang on the nut lock.

Rapid increases in Al, to or exceeding abnormal value, can sometimes be attributed to improper stack up of the

engine resulting in rub of the No. 2 bearing labyrinth seal against the turbine shaft. When Cr approaches the

abnormal value, it is a possible indication of wear in the No. 2 bearing housing, or front and rear turbine shaft.

Increases in Ag are indicative of bearing wear and are usually in combination with high Fe and Cu. Increases in

Cu and Mg individually, or together, are an indication of problem in the accessory case section.

Main bearing balls/rollers and races

Starter generator and accessory drive gears

Accessory case gears

Accessory oil pump

Accessory case bearings

Starter generator and accessory drive bearing cages.

Main bearing cages

Accessory case housing and adapters

A14