Don't Buy Univair Tailwheel Springs - January 2022

[tonycondon]

UPDATE APRIL 2022:

Just got a note from Univair that the new parts (which supposedly fit) are in stock.

[8296]

My question is will putting this spring on the aircraft set up the potential for tail shimmy? The wheel will now be in "trail' so to speak. Isn't this what you do not want to happen? I thought the swivel axis should point slightly forward to stop this problem. Simon in New Zealand says his aircraft does not shimmy with a zero bend spring. I know there is another index topic discussing this subject but I asked this same question last year stating that the(my) aircraft had extenders and got no reply.

My aircraft is a 1946 C120 with wheel extenders. Eventually I went from a Maule pnuematic to a Scott 3200 because all the talk back years ago was this would cure the shimmy issue. It did not. Could some one point me to the Forum discussion that will help me pick the correct tail spring for an aircraft of my configuration?

[8296]

I guess I need to go to the late vs early tailwheel discussion. Sorry for not taking a longer look at the forum thread titles before posting.

[tonycondon]

Univair has updated their shackle so it fits their spring set now.

[V529]

Thanks for updating. A "long haul" it's been.

[tonycondon]

To be fair, they updated the part a while ago, I just finally got around to updating mine.

[edidin]

FWIW, the shackle fit in the set I bought in 2023.

Also, perhaps not the correct thread, but the two square pads are 1/4" thick. Have seen references to 1/8" pads here and there.

While agree with Neil Wright that the retainer P/N 0442116 is in fact shown turned 90 degrees off in the IPC, turning it such that the 1/8" or so bent edges are parallel to the spring is not so that the edges don't contact with the spring under load, but rather so that the edges form I-beams to increase the bending stiffness of the plate. As shown, they don't contribute at all to stiffness in the direction the main spring flexes.