ICA-D212-725 (29)
Page 15 of 50
CHAPTER 29 – HYDRAULIC SYSTEM (29-00-00)
COPYRIGHT
2007 BY DART AEROSPACE LTD.
THIS DOCUMENT IS PRIVATE AND CONFIDENTIAL AND IS SUPPLIED ON THE EXPRESS CONDITION THAT IT IS NOT TO BE USED FOR ANY PURPOSE OR COPIED OR COMMUNICATED TO ANY
OTHER PERSON WITHOUT WRITTEN PERMISSION FROM DART AEROSPACE LTD.
Revision:
6
Date: 13.08.26
Table 29-2.
Troubleshooting (Cont.)
Indication of Trouble
Probable Cause
Corrective Action
RESERVOIR OVERFLOWS WHEN USING GROUND TEST UNIT.
Test unit pressure too low.
Check test unit setting.
Increase test unit pressure above
550 PSI (3792 kPa).
Pressure operated valve
malfunction.
Check for increased overflow
when flight controls are moved.
Replace valve.
Check valve in pump case drain
line closed.
Check for overflow with no
control motion.
Replace valve.
System check valve in pump
pressure line open.
Check for overflow with no
control motion.
Replace valve.
HIGH FREQUENCY VIBRATIONS DUE TO TAIL ROTOR CONTROLS.
Stiffness of binding in action of
tail rotor control hydraulic
cylinder.
1. Cylinder input lever binding on
spacer at bell crank. (Move lever
laterally to check.)
1. Polish spacer OD until free in
lever bearing.
2. Cylinder trunnions binding in
mounting plates. (Move cylinder
laterally 0.003 to 0.050 in. (0.076
to 1.27 mm).
2. Polish trunnion plate bushings
ID for free fit.
3. Cylinder input lever binding at
pivot.
3. Repair cylinder assembly per
overhaul instructions.
Binding in tail rotor controls.
1. Check pitch control tube for
binding in bearing in left side of
tail rotor gearbox.
1. Remove pitch change tube.
Clean ID of bearing and OD of
tube. Install and recheck.
2. Check lever on left side of tail
rotor gearbox for stiffness of
lower end bearing in alignment
motion. It stiffness occurs, twist
attached link to turn nut end of
bolt upward. Pull nut downward
with a spring scale. If force to
move bearing exceeds 10 lbs.
(44.48 N), lever is unserviceable.
2. Replace unserviceable lever.
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