JOAP ATOMIC EMISSION ROTRODE

NAVAIR 17-15-50.3

TM 38-301-3

T.O. 33-1-37-3

ENGINE:

J85-GE-5/-13

AIRCRAFT:

(T-38) (F-5)

JOAP ATOMIC EMISSION ROTRODE

Abnormal Trend

(PPM Increase

in 10 hrs)*

Normal Range

0-10

0-1

0-3

Marginal Range

11-28

1-2

2-3

1-2

2-4

4-10

High Range

29-49

3-6

4-7

3-8

5-11

11-21

Abnormal

50+

12+

22+

Average Concentration Other Elements:

Ni=1

Pb=2

Si=4

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.

No. 2 main bearing is a major problem area detectable by JOAP. These failures usually occur rapidly. Maintain

close surveillance even when small increases in Fe are noted. High Fe and Cu (with/without Ag) indicate main or

accessory bearing defect. Suspect first, No. 3 and No. 2 main bearings; next, Axis "E" accessory bearing. High Fe

is also frequently due to defect in gearbox Axis "B" bearing. High Ag alone may indicate fuel contamination of lube

system; recommend inspection of fuel oil cooler and/or fuel pump. Fuel contamination can also occur without

significant Ag present and is detectable by sample odor.

No. 1 bearing races

No. 1 bearing rollers and front frame casing

Nos. 2 and 3 bearing support

Accessory drive gearbox and PTO bearing balls/rollers and races

Accessory drive gearbox seal and bearing housings

Gearbox bearing spinning in liners, PTO scavenge tube

Main bearing carbon seal runners

No. 1 bearing compressor rotor front shaft

No. 2 bearing locknut and compressor driveshaft

No. 3 bearing locknut and turbine wheel shaft

PTO radial driveshaft, bevel gears, bearing housing, axial bearing support and

retainer

Accessory lube and scavenge pump spur gear, lube filter and oil cooler valve

Accessory drive gearbox shaft and bevel gears

Accessory drive gearbox gear locknut

PTO and No. 2 bearing retainer

A23