Table A-5. Copper levels between 100 and 200 PPM

NAVAIR 17-15-50.3

TM 38-301-3

T.O. 33-1-37-3

CGTO 33-1-37-3

SH-60B, SH-60F, HH-60H, MH-60S, MH-60R (Cont.)

TAIL ROTOR GEARBOX

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-5 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 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.

Table A-5. Copper levels between 100 and 200 PPM

Hours (since new

Cu (PPM)

Action

bushing)

≤ 100

≤ 200

No maintenance required

≤ 100

> 200

Drain, refill. Sample @ 25 hours

>100 & ≤ 200

≤ 100

No maintenance required

>100 & ≤ 200

> 100

Drain, refill @ 200 hrs since new

bushing

> 200

≤ 75

No maintenance required

> 200

> 75*

Perform dimensional inspection of

bushing

* for two consecutive 60-hour samples

Mo -

Molybdenum is not regarded as a critical wear metal in the H-60 tail rotor

gearbox. Sources are solid film lube on the inner diameter of the bevel gear

or grease used to lubricate the inboard retention plate splines on installation.

Nickel is not regarded as a critical wear metal in the tail rotor gearbox. Nickel

sources are either benign wear or wear that is more accurately signaled by

another wear metal. Most likely source of nickel wear is wear on nickel

plating on outer diameter of inboard retention plate sleeve. Sleeve provides

contact surface for output oil seal and can result in oil leakage if wear

becomes excessive. Leakage should be detectable by routine inspection

before if exceeds allowable limits.

Other sources of nickel are as follows:

Nickel is used as base plating on input flange sleeve inner diameter and pitch

change shaft outer diameter. Because this base plating is under 0.005-0.007

inch of chrome plating, abnormal levels of chromium would be evident in the

oil samples for some time before wear penetrated to nickel plating.

Practically all steel alloys used in tail rotor gearbox components include a

small percentage of nickel. This includes gears, bearings, liners, servo fitting

and link, bolts, washers and nuts. Because these alloys are all over 90

percent iron, wear on a steel component would produce many times more

iron than nickel.

A170