Landing gear oleos- early 7AC Question

[zipperdu]

My newly purchased Champ has the Landing Gear Snare Cable installed- I've looked at AD 47-20-02 and Service Helps and Hints #12 and they indicate the cables are required on 7AC s/n 226 thru 3721. My question- What type of pistons are installed on serial numbers before 226 (like mine) that the AD and SH&H are not applicable by serial number.......just one more of many questions trying to learn a new airplane!

Thanks folks, Jon Marion N81488

[Paul Agaliotis]

Joe,
I would guess the pistons were aluminum or brass. Aeronca must have changed to a fiber piston for the listed serial numbers. You might pull the drawing and see if it has any information.
Paul

[CptKelly]

I read a while back that the fiber pistons were supposed to be replaced with a metal unit. I believe there was a service letter on it. Seems to me that the fiber pistons were the reason that the safety cable was required. I'm assuming that the replacement pistons were constructed out of aluminum.

Mike

[Paul Agaliotis]

Mike,
The snare cable was used as an interim repair until the replacement of the fiber pistons as called out in the Service Letter.
The AD 47-20-02 required the replacement of the fiber pistons, some owners just left the snare cables on. I have them on the 7AC.
Jon's question, if I read it right, is the curiosity of the serial numbers prior to #226. And what type of piston material was used.
Paul

[MikeB]

I just left them on my 7AC too. Kind of like wearing a belt and suspenders for extra protection .

Mike

[zipperdu]

Yeah, I was hopeing to remove the snare cables, but not knowing how the pistons were made, I guess I'll leave the cables on....just in case.
Thanks everyone!

Jon Marion N81488

[james gevay]

My Aeronca Champs and Chiefs book by Lasher describes the problem pistons to be replaced in the AD as "laminated synthane".
As for why the pistons before serial #226 don't have to be replaced, that's a good question.
Maybe Bill Pancake would know.

Another part they had problems with are the 1-316 retainers at the very top of the oleos, their the part with the AN4-23 bolt through it. I know some early planes were micarta and Aeronca changed to aluminum sometime in production.
Here's a picture of the old micarta parts and the newer aluminum ones.
The Aluminum retainers came out of my plane and the old micarta ones came from some spare oleos I came across.
Notice the crack in the left one.




Here's a picture of the aluminum pistons that were in my oleos before they were rebuilt by Safe Air some years ago. In the front of the picture are the two 1-319 packing glands, their at the bottom of the springs and the packing would be between them and the stuffing box, and then the piston underneath it all.
Notice the scoring and the metering holes in the center of the pistons.

[joea]

Many people leave them on "just in case" they are needed. Still, I have heard of the old fiber piston being found in struts being overhauled and they were supposed to have been replaced YEARS ago, so you never know unless you have had the strut out and inspected it.