Sources of wear metal elements in oil samples are given in Table A-3.

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

Sources of wear metal elements in oil samples are given in Table A-3.

a. Iron (Fe) - Iron wear particles may indicate wear of the gears, bearings, bearing liners, or pitch control

shaft. For further information on iron wear metal, see paragraph 6a below.

b. Aluminum (Al) - Aluminum wear particles may indicate wear of the inboard retention split cones (copper

would also be present), or corrosion of the input pinion plug. Aluminum is not used as a primary means of

detecting component wear. If titanium is normal, no action is required.

c. Titanium (Ti) - Titanium wear particles may indicate wear of the inboard retention plate splines or the

input flange splines. Wear of the inboard retention plate splines would also result in high aluminum and copper

wear metal levels. Wear of the input flange splines would also result in high aluminum wear metal levels.

Performance of torque checks on the nuts/bolts connecting the input flange/inboard retention plate to the gearbox

is used to determine if wear of these splines is present. See also paragraph 6c and 6d below.

d. Magnesium (Mg) - Magnesium wear particles usually indicate that corrosion of the gearbox housing(s)

is present. The most common location of gearbox corrosion is the tail rotor servo bore area. See also paragraph

6b below.

NOTE

The squadron will submit a baseline sample 9 13 hours after installation of new

oilite bushing.

The oil may not have been changed when the pitch change shaft with the oilite

bushing was installed in the tail rotor gearbox

e. Copper (Cu) Copper is not a critical wear metal in the H-60 tail rotor gearbox. Copper usually

indicates wear on the pitch change shaft oilite bronze bushing from sliding contact with the inner diameter of the

steel output bevel gear. Iron from the bevel gear will often accompany copper. Wear on the oilite bushing is

common and is the subject of dimensional inspection during scheduled removals. Wear is typically greater in the

first 100 200 flight hours on a new bushing installation. Wear is the greatest with a new bushing in a 70358-

26600-044 tail rotor gearbox. (The 044 gearbox contains the output bevel gear with shotpeened inner diameter,

which has a rougher surface finish, thereby causing greater abrasion on the oilite bushing.)

Because wear is common and regular scheduled inspections gage wear on the oilite bushing, limited

maintenance action is recommended for copper or copper/iron contamination in the first 100 hours of service on a

new bushing. The only exception to this is if copper levels exceed 200 PPM and/or copper is accompanied by

other critical wear metals. (See Table A-2 for applicable maintenance actions and other critical wear metal

criteria.) Between 100 200 flight hours, maintenance actions should be limited to oil change if the copper level

exceeds 100 PPM, provided other critical wear metals are not involved. After 200 flight hours, a dimensional

inspection of the bushing should be performed only when copper levels exceed 75 PPM for two consecutive

monitoring intervals. Other sources of copper in the tail rotor gearbox are the aluminum bronze split cones on the

inboard retention plate and the cage material on the duplex ball bearing in the tail rotor servo coupling. Split

cones can contribute copper and aluminum to the oil if wear/fretting occurs. (See supplementary information for

aluminum.) The duplex ball bearing is inside the pitch change shaft and is not normally exposed to oil flow.

A153