JOAP ATOMIC EMISSION ROTRODE (cont)

NAVAIR 17-15-50.3

TM 38-301-3

T.O. 33-1-37-3

CGTO 33-1-37-3

ENGINE:

JT8D-9A (NAVY ONLY) (Cont)

AIRCRAFT:

(C-9B/DC-9)

Nos. 1, 3, 4-1/2, 5 and 6 roller bearings and races,

No. 3 bearing spacer/gearbox drive bevel gear.

Nos. 2 and 4 ball bearings and races gearbox gears.

Nos. 1 and 6 scavenge oil pumps.

Main bearing wear

No. 3 bearing cages

Nos. 1, 2, 4, 4-1/2, 5 and 6 bearing cages

Nos. 4, 4-1/2, and 5 scavenge oil pump

Gearbox main oil pump

Gearbox housing and adapter

NOTES

1. Abnormal concentration of wear metal discovered during Spectrometric Analysis should not by itself be

justification for engine or oil-wetted component removal: a positive correlation should be made with other

indicators, such as solid metal on chip detectors and/or solid metal in filter, vibration, burned oil, etc.

2. Engines with an indication of high or abnormal parts per million wear metal concentration should initially be

inspected for solid particulate in the form of metal slivers, flakes, etc. If the initial inspection does not indicate

solid particulate, then oil sampling should be accomplished at a reduced interval for a limited period of time,

but without flight restriction. During the period of reduced sampling interval, operators should have an

increased awareness of other oil system indicators.

3. Abnormal Fe and Cr concentrations at the microscopic level are not uncommon, and have been attributed

to the following:

a. Rust accumulation on oil-wetted components: Rust within the engine oil system is not common, but

may occur if the engine has been out of service for an extended period of time.

b. Bearing outer race slippages: Abnormal concentration of Fe may result if a bearing outer race slips

within the bearing's liner. Bearing outer race to liner slippage is common within the gearbox. This condition

may be temporary, or may continue without an adverse affect on component operation.

4. If increased wear metal concentrations are the result of a temporary condition, the levels will plateau, and

eventually decrease through normal usage.

5. The oil system should not normally be drained and flushed, except if contaminated by hydraulic fluid, fuel,

etc.

6. If darkening of the oil occurs, the most immediate concern is overheating of the oil. Oil overheating will

generally be evidenced by darkening of the oil, accompanied by a burned oil smell (see P&W Maintenance

Manual P/N 481671, Troubleshooting "Black Oil"). Synthetic ester-based aviation oils may undergo a color

change in service. Synthetic turbo oils contain oxidation inhibitors in their formulations, and most, if not all, of

the better oxidation inhibitors are photosensitive. A new oil, light straw in color, may go through all colors of the

spectrum and end up jet black as it performs its service. The color is imparted by the oxidation inhibitor, which

darkens as it performs its function.

A-70