Remove tail rotor servo.

NAVAIR 17-15-50.3

TM 38-301-3

T.O. 33-1-37-3

CGTO 33-1-37-3

MH-60A/UH-60L/MH-60L/MH-60K (U.S. ARMY ONLY) (Cont.)

TAIL ROTOR GEARBOX

CAUTION

Damage to equipment will occur if foreign objects enter gearbox. Foreign objects may

enter gearbox when tail rotor servo is removed. Ensure that no foreign objects enter the

gearbox during performance of this task.

Remove tail rotor servo.

Inspect inside of tail rotor gearbox, especially the inside diameter of the input bevel pinion, for buildup of

sludge and debris accumulation. Remove sludge/debris using a clean dry cloth. Insure no debris is left inside the

gearbox.

g. Flush gearbox with clean lube oil. Repeat using clean oil until oil drained from gearbox is clean with no

trace or debris. Insure oil stream is directed against entire inside of gearbox to insure all debris is flushed from the

gearbox.

Install chip detector self-closing valve, chip detector, and electrical connector.

Install tail rotor servo.

Fill gearbox with proper amount of oil.

Reinstall filler cap.

Make sure area is clean and free of foreign material.

The following requirements are for oil sampling of the tail rotor gearbox used on Army H-60 Black Hawk

Helicopters:

1. Water content shall be checked on every sample. Maximum water concentration is 1000 ppm.

2. The primary serviceability criteria for this component is the presence of chips sufficient to cause a chip light

indication. Oil analysis shall be used primarily to trend increases in Fe levels, and to ensure that the lubricant

condition is acceptable, and that the lubricant is free of harmful contamination.

3. Spectrometric criteria are given in TM 38-301 except as follows. A spectrometric analysis shall be conducted

on all samples. Results shall be interpreted as follows:

a. Fe - If the iron concentration is greater than 46 ppm, or if an increase of more than 18 ppm occurs

between any two consecutive samples, a ferrographic or microscopic analysis must be preformed. The results of

the ferrographic or microscopic analysis must support the spectrometric analysis findings before a

recommendation for removal is issued.

b. Mg - If the magnesium concentration exceeds 50 ppm, have the unit replace the lubricant, and inspect

the gearbox for signs of corrosion, especially at the interface between the center housing and the servo. Continue

to monitor the magnesium level. If magnesium continues to increase, have the unit drain and flush the component

at the next PMS-2 phase inspection. More frequent lubricant change is not required. Removal of the gearbox shall

be based upon the results of the gearbox corrosion inspection.

A158