ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev.
9
MM-4-31
Dec
14/17
4-16. Draining – Tail Rotor Transmission
A. If equipped with a chip detector, remove the chip detector from the quick disconnect
receptacle.
B. Place a suitable container under the receptacle/magnetic plug.
C. Remove the quick disconnect receptacle/magnetic plug and drain the transmission.
D. When the transmission is drained, replace the crush washer and reinstall the
magnetic plug/chip detector. Tighten the magnetic plug/chip detector until the turning surfaces
are in contact, then tighten an additional 135° (not to exceed 35 in-lb/4 Nm). Lockwire the
receptacle/magnetic plug to the sight glass and the filler plug after the transmission has been
serviced.
E. If equipped with a chip detector, reinstall the chip detector.
4-16.1 Flushing – Tail Rotor Transmission
A. Drain the oil (paragraph 4-16, steps A through C only).
B. Remove the filler plug, sight glass, and top visual inspection plug (if not already
removed) from the gearbox.
C. Inspect the gears closely for cracked or missing teeth and the gearbox for damage.
D. Use a syphon sprayer with kerosene, mineral spirits, or equivalent oil-based solvent
to spray down the interior of the gearbox and flush any debris out of the gearbox. Direct aim the
sprayer around the inside of the gearbox to flush the input and output bearings, while rotating
the gearbox.
E. Loosely install the bottom drain plug, sight glass, and fill plug.
F. Add one-half quart of the gear lube that is currently used in the gearbox (Table 4-1).
G. Rotate the gears at least ten times to circulate the oil.
H. Place a container covered with a clean, white cloth or filter under the drain plug.
Remove the drain plug and drain the oil into the container while rotating the gears. Allow the
gearbox to drain completely.
I.
Inspect the cloth for contamination. If there is contamination, repeat steps D through I
using a new cloth or filter each time the gearbox is drained. Proceed to step J if there is no
contamination.
J. Replace the crush washer and reinstall the top visual inspection plug. Tighten until
the turning surfaces are in contact, then tighten an additional 90°. Lockwire the plug to the pivot
bushing (.032).
K. Replace the crush washer and reinstall the bottom magnetic plug/chip detector.
Tighten until the turning surfaces are in contact, then tighten an additional 135° (not to exceed
35 in-lb/4 Nm).
L. Service the gearbox (para. 4-15).
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