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Aircraft
Maintenance TroubleShoot
Landing Gear Vibrations
First of all, try to locate which landing gear could be the
culprit. Usually nose landing gear vibrations manifest itself as shimmy. In
those cases check:
1- Check an out-of-round tire. Excessive deformation could induce vibrations and
in some cases quite severe. Wheel/Tire assembly vibrations are quite easily
identified because they remain after take off for while because the assembly is
still turning. Also check wheel balance. Some wheel assemblies are factory
balanced with screws; if one of them is missing, vibrations could appears.
2- If the vibrations disappear immediately after rotations, it could be due to
loose torque links or a shimmy damper which not work properly.
3- Verify for unusual or excessive backlash in the transmission components from
the pedals to the wheel.
see Cessna Nose Wheel Shimmy
WHEN VIBRATIONS ARE FELT ONLY ON PEDALS OR IN THE FUSELAGE REAR
PART, check the following:
1- Check main wheel for out-of-round or out-of-balance.
2- Check free plays on the torque links.
3- Service properly the shock absorbers.
4- Verify for a drag brake. If one lining is not releasing properly, it could
lead to a brake vibration and consequently a pedal vibration.
5- Verify torque on attaching bolts and wear on bushings.
CASA's C-212 SHIMMY, verify the following:
1- Check an out-of-round tire. Excessive deformation could induce vibrations and
in some cases quite severe. Wheel/Tire assembly vibrations are quite easily
identified because they remain after take off for while because the assembly is
still turning. Also check wheel balance. Some wheel assemblies are factory
balanced with screws; if one of them is missing, vibrations could appears.
2- If the vibrations disappear immediately after rotations, it could be due to
loose torque links.
3- Verify excessive backlash between the steering actuator's teeth and the
gear's teeth.
4- Check steering selector valve's cables for the right tension, put more
attention on the follower cable than the cable coming from the steering wheel.
The tension should be 35 lbs for the follower and 17 lbs for the other.
5- Check steering accumulator pre-load.
6- Check pressure limiter valve on the steering selector valve. It should open
when pressure is more than 150 PSI.
7- Verify pressure reducer valve for proper operation.
8- Service properly the shock absorber.
9- Verify shock absorber's bushing. If they have too much wear the strut could
vibrate during the take off and landing run.
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To Kill and kill and kill
was the cry. To burn, to destroy, to devastate, to lay waste. Men heard
the madness and knew it for madness and embraced it, some with fear and
some with joy. Kill or be killed. Survive or parish.
The Red Knight of Germany
by Floyd Gibbons 1927
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