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STEVE ELLS replied to the topic 'C182RG Nose Wheel Shimmy' in the forum. yesterday

Hi, I have a few suggestions. First, the shimmy dampener body does not move when you swing the nose gear left and right; the piston inside the shimmy dampener does.
As you point out the shimmy dampener does not have to be removed from the nose gear strut to be serviced with hydraulic fluid (Mil H 5606). The procedure from the manual is as follows:
a. Using the tow bar, turn the nose wheel strut to the extreme left position (thru serial
R18200710), to the extreme right position (beginning with serial R18200711), against
the stop. This will place the shimmy dampener piston to the rear of the cylinder and
eliminate the possibility of trapping air in the cylinder.
b. Remove the filler plug and fill with hydraulic fluid.
c. Replace filler plug and turn nose wheel strut through its entire travel several times.
d. Return strut to the extreme left position (thru serial R18200710), to the extreme right
position (beginning with R18200711) against the stop.
e. Remove filler plug and add whatever fluid is needed to fill the cylinder.
f. Replace and safety the filler plug.
If you have to add more than an ounce or two of fluid, it's likely that the dampener is leaking and needs to be removed and repacked prior to servicing. The packings are generic O rings. I order a packing kit from McFarlane Aviation. Cost is less than $10.
Other items to check are the balance of the nose tire wheel assembly; an out of balance assembly can cause shimmy. The next step is to check for wear and slop in the nose gear torque links. If these links aren't tight then the shimmy dampener won't be able to dampen shimmy since the shimmy won't be completely transferred to the dampener.
Unfortunately there is one more problem with R182 shimmy dampener installations. The collar that is bolted into position on the nose gear strut and that the shimmy dampener is bolted to has been found to be weak. As I understand the problem, the shimmy dampener clamp was not strong enough and a locating pin welded into the inside surface of the clamp was to small to prevent the clamp from moving relative the strut. This movement lessens the stability of the dampener on the strut which reduces the effectiveness of the dampener.
Cessna issued Service Bulletin 84-15R1 on October 5,1984. This SB said: "An improvement of the shimmy dampener installation has been incorporated on current production aircraft and includes a thicker shimmy dampener clamp, a larger locator pin and corresponding nose gear strut outer barrel change."
Service kits SK182-83 and -84 provided instruction and parts. In 1984 the cost of the SK was $418. These kits are still available from Cessna but the cost is now around $15,800.
Bad clamps are pretty easy to see. Put a sharp mark across the clamp/strut and move the nose tire back and forth. Any movement of the clamp is bad news.
If you see clamp movement, remove the clamp to determine the amount of wear in the strut barrel.
You may be able to find a complete nose gear assembly from a later model R/TR 182 in a salvage yard that costs less than the Cessna kit.


STEVE ELLS replied to the topic 'Manifold Fluctuation' in the forum. yesterday

Hi Sorry it's taken a while to respond.
Are you familiar with the term "bootstrapping?" Bootstrapping is when there's only enough exhaust gas pressures passing by the turbine wheel in the Turbocharger to provide a neutral (not positive) pressure at the engine intake. I mention this because the erratic MAP begins it starts when you start your climb to a higher cruise altitude and stops when you descend.
When the turbocharge system is bootstrapping any small change in altitude (air density) or aircraft attitude (variances in inlet air pressure) will affect the MAP in a linear fashion.
It's pretty easy to see that the cure for bootstrapping is to increase the engine RPM, thereby increasing exhaust pressures which results in a positive inlet air pressure.
If you took closely at the relationship between RPM and MAP, especially at about 1:20 into the flight you'll see how RPM affects both fuel flow and MAP. In fact, this relationship is evident all through the charts you've provided.
Mouse Milk is the best stuff for lubing the wastegate so you did the right thing there.
I suggest that whenever you experience erratic MAP, especially at higher altitudes that you bump the RPM up; I think you'll find your erratic MAP problem goes away.
Happy Flying


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