TAIL ROTOR GEARBOX (Cont) - TM-38-301-30189

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

during this period, and no abnormal upward trend occurs, change oil to

remove potentially abrasive iron particles and return to normal sampling."

If an abnormal iron level or abnormal upward trend occurs, without

accompanying copper, the recommendation shall be "Change oil, submit

sample after initial turn-up, and submit samples approximately each 10

flight hours for next 30 flight hours. If iron level remains below marginal

range and no abnormal upward trend occurs within this 30 hour period,

return to normal sampling". If the iron level climbs to the marginal range or

above or if an abnormal upward trend occurs within this period, the

recommendation shall be "Perform serviceability check of tail rotor gearbox

in accordance with the general aircraft information manual".

Ag -

Primary sources of silver in the tail rotor gearbox are plating on male

splines on bevel gear and pinion gear. These splines mate with inboard

retention plate splines and input flange splines, respectively. Though not in

wetted area of the gearbox, wear particles can, in some cases, migrate

through faying surfaces into the oil system. Secondary sources of silver in

the tail rotor gearbox are plating on inner diameters of inboard retention

plate sleeve and input flange sleeve. These surfaces are press fit onto the

retention plate and input flange, respectively, and are not subject to normal

wear. If the silver level enters the marginal or high range, the

recommendation shall be "Submit oil samples approximately each 10 flight

hours for the next 30 flights hours. Do not change oil at this time. If silver

level does not increase to abnormal range and no abnormal upward trend

occurs within this period, change oil at the end of the 30 hour period and

return to normal sampling".

If silver level enters the abnormal range, or if an abnormal upward trend in

the silver level occurs, the recommendation shall be "Discontinue flight

operations and check for proper torque on inboard retention plate bolts and

on input flange nut in accordance with transmission system maintenance

manual". If proper torque is confirmed, the recommendation shall be

"Change oil, submit oil sample after initial tuneup, and submit oil sample

approximately each 10 flight hours for the next 30 hour period, return to

normal sampling". If the silver level returns to the marginal range or above,

or if an abnormal upward trend in the silver level occurs within this 30 flight

hour period, the recommendation shall be "Immediately discontinue further

flight operations, remove inboard retention plate, and inspect retention

plate splines, bevel gear splines, and split cones for fretting/wear, in

accordance with transmission system maintenance manual. If no

discrepancies are identified in this inspector, remove input flange and

inspect input flange splines and pinion gear splines for fretting/wear."

Al -

Aluminum by itself is not considered a critical wear metal in the H-60. If

Titanium is normal, no action is required. Aluminum contamination only

would indicate internal corrosion. The three aluminum components that

typically give apparent indications of wear resulting from corrosion are the

input pinion plug, the filler cap assembly and the chip detector assembly.

These components are not normally subject to service wear. Most

probable source of corrosion product is the input pinion plug, a low point in

the gearbox. Wear/fretting on the inboard retention plate split cones can

produce aluminum and copper. If wear/fretting on the split cones is

occurring, titanium will begin to show in the soil samples.

A167