INTERMEDIATE GEARBOX (Cont)

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, UH-60L (Cont)

EH-60A, MH-60L, MH-60K, MH-60S, MH-60R AND VH-60N

INTERMEDIATE GEARBOX

range or if abnormal upward trend occurs, recommendation shall be to

"Discontinue flight operations and check for proper torque on the input and

output flange nuts in accordance with transmission system maintenance

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

oil and submit oil sample after initial turnup and approximately each 10 flight

hour period, return to normal sampling". If aluminum level returns to high or

abnormal range, or if abnormal upward trend recurs at any time within this 30

flight hour period, recommendation shall be to immediately discontinue

further flight operations, remove input and output flange and inspect flange

splines for fretting/wear in accordance with transmission system

maintenance manual.

With a new or freshly reworked gearbox, magnesium usually indicates minor

manufacturing/assembly debris from housings. Otherwise, magnesium

contamination indicates internal corrosion or abrasive wear. Magnesium

components in the intermediate gearbox include the input housing, center

housing, output housing, and the lubrication spiral which provides oil to the

output bearing on the output bevel gear. Due to moisture accumulation,

vulnerability to corrosion is increased if intermediate gearbox has been

serviced but has not been operational for an extended period. If corrosion

occurs due to moisture contamination, magnesium is sometimes

accompanied by iron. If magnesium level enters marginal or high range,

recommendation shall be to "Sample at approximately 10 flight hours interval

for next 30 flight hours. Do not change oil at this time. If magnesium level

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

in this initial 30 flight hour period, return to normal sampling". Maintain

normal sampling interval thereafter until abnormal level or abnormal upward

trend occurs. Due to relative softness of magnesium alloys in this gearbox,

risk of abrasion is not sufficient to justify oil change unless abnormal upward

trend occurs or magnesium level enters abnormal range. If magnesium level

enters abnormal range or if abnormal upward trend occurs, recommendation

shall be to "change oil, submit turn-up sample, and submit samples

approximately 10 flight hours for next 30 flight hours. If magnesium level

remains below marginal level and no abnormal upward trend occurs within

this 30 flight hour period, return to normal sampling." If magnesium level

returns to marginal range or above, or if abnormal upward trend occurs,

recommendation shall be to "Submit oil samples approximately each 10 flight

hours until intermediate gearbox can be removed due to internal

corrosion/wear".

A-163