T337C Gear question/issue
 

Hi all,

It appears that the downlocks on my T337C are not retracting (or are not staying retracted), so when I put the gear down, the downlocks are getting shoved back out of the way by the struts which is causing some abnormal wear and--I think--some intermittent hesitation. From the service manual it looks like the downlocks should remain fully retracted by virtue of return flow from the main actuator. But instead they are popping back out enough that the struts are shoving them out of the way, before they pop back to lock. We have already cleaned and overhauled the check valve, so does this point the finger at the priority valve in the power pack? Any insights appreciated!

Thanks in advance,

Allen

Allen, is this scenario while on service jacks? or in the air? If on jacks how are you swinging the gear? With mule or hand pump?

Yes, it's up on my jacks right now, and it's the same with the mule or hand pump. I think it's the same in the air, too, which would explain some abnormal wear on the struts where the struts are contacting the downlocks and pushing them back out of the way.

It seems like they should remain retracted. If we stop mid-cycle and physically push the downlocks into a retracted position, they remain there out of the way until they are popped out to lock the gear once it is in place. When you raise the gear, they pop back to fully retracted to unlock the gear, and remain there while the gear goes up and locks. But when you put the handle in the gear down position, they float out a few inches instead of staying retracted.

I would start with the left down lock (because that's where flow starts) and overhaul it. Then overhaul the right downlock. Be extra carefully with the "shims" when reinstalling. Overhaul length is important...

Downlocks overhauled...
 

It appears this solved the issue. My mechanics overhauled both downlocks, and now they both remain retracted until the gear is fully extended. We did some gear swings today and all looked good. We'll put the interior back together and then I will go test fly it to see if all is well. Thanks for the help!!