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<<My nose gear freefall just fine on jacks, but is sluggish in the air. The extra 20 pounds will do it.>>
Bill,
If you are having difficulty with the emergency extension with the stock gas strut, I would venture to guess you have excessive friction or binding in your system. While a stronger gas strut will produce a better free fall extension, it treats the symptom and doesn't fix the root cause. The standard gas strut is more than sufficient to push the nose gear out even at 100+ KIAS.
There are a number of places where friction or binding can occur and prevent the standard gas strut from doing its job. The two links and the nose gear must swing in the same plane during the entire retraction cycle or else binding will occur. Excessive compression on the nose gear bearings is another popular source of friction causing free fall difficulty.
Things to check: With the over center link disconnected from the nose strut, it should swing freely, yet have no side play in the bearings. The length of the spacer holding the two bearing plates apart is absolutely critical. If it is too short the compression on the bearings will produce friction. If it is too long you will have side play in the strut. (I eventually replaced the steel tube in front of the strut with the parts in the attached photos. They make the precise adjustment of bearing play/friction a 15 second job.)
Once the bearings are ruled out as a source of friction, the alignment of the over center linkage to the strut needs to be checked. A simple way of doing this is to disconnect both the gas strut and hydraulic cylinder, so that the linkage can be moved freely. With the nose strut in any position from fully extended through fully retracted, the end of the over center linkage should slide in and out of the from between the tabs on the nose strut without applying any pressure to either tab. If at any time, the links apply pressure to one tab or the other, then the axes of rotation for the nose gear and the over center links are not parallel causing the parts to swing through different planes.
Chris Zavatson
N91CZ
360 std.
Christopher Zavatson
BAE Systems
(408)289-4329
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