TAIL ROTOR GEARBOX (Cont) - TM-38-301-30191

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

If verified, recommendation shall be, "Discontinue flight operations and check

for proper torque on inboard retention plate bolts and the input flange nut in

accordance with the transmission manual". If proper torque is confirmed, the

recommendation shall be "Change oil and submit oil sample after initial turn-

up and approximately each 10 flight hours for the next 30 flight hours. If

titanium level remains below the marginal range, with aluminum levels in the

same range, and no abnormal trend occurs during this 30 flight hour period,

return to normal sampling". If the titanium level returns to the high or

abnormal range, accompanied by aluminum in the same range, or if an

abnormal trend occurs at any time within the 30 flight hour period, the

recommendation shall be, "Immediately discontinue further flight operations,

remove the tail rotor servo and inspect for sludge/deposit accumulation in the

gearbox and in the I.D. of the input pinion. Remove any accumulation with

clean dry low lint cloth. If no discrepancies are identified in this inspection,

remove inboard retention plate, inspect the retention plate splines, bevel gear

splines and split cone for fretting/wear in accordance with

the transmission system manual. If no discrepancies are identified in this

inspection, remove the input flange and inspect the input flange splines and

pinion gear splines."

Chromium in the tail rotor gearbox indicates wear of the input flange sleeve,

inboard retention plate sleeve, or pitch change shaft outer diameter. Normal

service wear on either the input flange sleeve or inboard retention plate

sleeve is benign and requires no maintenance action until leakage rate

exceeds allowable limits of the general aircraft information manual. Existing

300 hour scheduled removal and inspection of the pitch change shaft is

adequate for monitoring normal wear of the pitch change shaft outer

diameter. If the chromium level grows beyond 25 ppm, abnormal wear may

exist. The recommendation for chromium above 25 ppm shall be "Remove

pitch change shaft assembly at earliest opportunity and inspect for unusual

wear on shaft outer diameter."

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

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.

A169