The main problem (or maintenance mightmare) with the design of ALL the T/W assys is the release pin. I see all the vendors using the same design at the release pin, so they ALL need servicing at 25 hr intervals, with constant attention to the condition of the pin.
So the question of which is better goes to the yoke design, where one vendor uses bearings as opposed to bushings. Certainly, one is more high-tech, but is it needed, or does it have any benefit?
I cannot say that the JD Air yoke will last longer, but the loads on this part are in the kingpin area - not where the sealed bearing is under the kingpin. Likewise, I am not a bearing engine ear, so I cannot say the needle bearing is a reasonable change (cost effective) from the bronze bushing, tho it seems it would be if this were a device that rotated constantly, or more than 90deg in normal use. If I can recall my interweb searching for this sort of bearing requirement on an RG gear system, the bronze bushing wins there. That is the application on the B25, anyway, tho I think the bushings are steel. I can also say the C45 does not use bearings on the gear system, nor in the tailwheel assy, other than wheel bearings.
Both of those ships were built in a time when $$$ was not such a problem compared to availability of the aircraft.
Seems our tailwheel fits into the same sort of answer: the bushing is the correct answer at the kingpin, both in cost and longevity. Fleet experience will tell us if the bearings, as used by JD Air, are more effective.
Keep in mind, the release pin needs 25hr interval attention - this is non-negotiable. Might as well lube the bushing at the same time, and save some $$$ for AVGAS.
Maybe a couple of the fellas in Team Aerodynamix can run a test for us? That would get us an anwer much quicker that any of us could do. I trust Mike to tell us thumbs up or down. Mike?
Carry on!
Mark
).
