Front suspension check

[Roger Lee]

Important FYI,

 

I have found lately some loose front suspensions and steering wobble in the front end. If you grab the plane by the base of the prop and lift the plane off the ground an 1"-2" and let it back down slightly firm the front suspension should be fairly stiff and firm with only a slight cushioning. You should have no free play up and down unless you still have that old spring (get rid of it). The up and down free play is from the red elastomeric spacers getting crushed down or split. If this happens the red spacers need replacement. The front end up and down movement should be firm. The other check is to have someone push down on your tail and grab the front wheel. It should have no more than about 1/4" free play left or right. The more free play the faster the wobble will develop. I have been finding some CT's with front end wobble and or free play up and down. The sooner you find and correct this the better. If you allow this free play to continue it will get worse until the front end wobble is felt through the whole plane during taxi and landing. You will wear out the front suspension guide pin and the slot it rides in. The excessive wear comes from the up and down motion from bad spacers and especially the old spring. If you have the old front end spring get rid of it. The red spacers for the spring replacement is free. The pin is an easy fix the slot it rides in if damaged beyond repair can be a $1800 front suspension replacement. I have had a couple of planes in the shop lately. The fix is to drop the front end (not hard). Get a new guide pin from FD (not expensive). Hopefully the pin took more of the wear and the slot edge wear is minor. File off the sharp edges on the slot exterior. The new pin will be larger than the hole it goes in length wise. You have two choices here. Grind down the pin to fit the hole. Width wise it will be okay it is only the height that needs to be reduced. Don't mess with the pin or guide slot width. The other way is to take a Dremel tool with a small tip rotary grinding tip and very slowly elongate the hole in the front suspension where the pin goes in. I hand fit these and they are perfectly tight once done. I make the pin snug enough that it has to be tapped in place (not pounded). Make sure when you replace the red spacers and washers you apply a little grease to them so they can move slightly and not bind up. Leaving these completely dry may lead to their over stress and failure. This job usually takes me 2 hours from start to finish with the front end back on the plane. This isn't a hard job, just takes a little time. Finding it sooner rather than later is the best cure. Once I fit a pin the front end wobble and up and down free play are totally gone. The front end is rock solid.

 

If you find this and have any questions you can call me.

[gisurvey]

Roger, can you give me the FD part number for the guide pin please? Thank you.

 

Alec.