Defective 'new' torque tube bearings?

[Daniel Haumesser]

Now that the Horne AD is going full steam ahead, I was wondering if anyone out there has replaced their old torque tube bearings with new only to find later that there is play in the stabilator originating from the new bearings.

I completed my Horne AD (and reported it) early when the AD came out. There were no cracks and after a good cleaning lubing, reinstalled the tube and horne with all new nuts and bolts. The delima at the time was weather to reuse the bearings or buy new. Since everything I read said repacking was almost always fine, thats what I did. They were VERY dry. the grease was more like cracked putty. SO a few flying hours later I notice play in my stabilator, front to back and up and down. Very little but definitely play where there didn't used to be and isn't allowed. After checking the bearing blocks and every other possibility, it was concluded the play was from the bearings (I found much later that the bearings were ok, the play was from the inner torque tube blocks in the stabilator). So at my next Annual, the tail was again taken apart and new bearings installed. After reassembly, the tail was tight and i was very happy. HOWEVER, approximately ten hours or less later, the tail is loser again! I practically climbed inside the side inspection panel by the tail while someone moved the stab front, back, up and down. Again, I made certain the bearing blocks were solid and not moving, the high sheer rivets were tight and there was no movement between the norne and torque tube. But when I shined a bright light onto the port side bearing (yes, you can actually see the inside of it when properly contorted) I could actually see lateral movement between the innner ring and outer ring of the bearing.

So my questions:

1. Have i adequately convinced the readers that its a bad bearing or can someone think of something I may be missing.
2. Has enyone else gotten new bearings which were bad?

The place i purchased them from (won't say the name because until now I've been very happy with my purchases from them, and don't want to ruffle feathers) insists they are not aware of any issues and has never heard of new ones being bad. They said if I purchased another set from them and sent back the old ones, they would send them to their supplier, and if the supplier agreed they were bad, only then would they refund the purchase price of the first set only. That was very frustrating and dissapointing to me and I'm still stewing on how to respond to that.

I spoke with the folks at Heritage Aero and was told that its not uncomon to get new bearings that are bad, thats why they recommend reusing the old ones if at all possible.

Because this will be the third time I've had to get this tail defeathered and still no guarentee I won't get another bad set!!

P.S- sorry this is so long.

[N3322G]

Daniel,

I only have experience with the Twin and it has a tail AD that replaces rivets to prevent play in the stab - does your single have the same AD?

Philip at Webco noticed play in the stab - the AD had been signed off but only one of the four locations had the rivets replaced. Had that one fixed right away.

[Daniel Haumesser]

Yes, I forget the AD number but i believe its the same one, for hight sheer rivet inspection/replacement? That was actually the first thing I checked since I still have not replaced the rivets with the kit. Inspections reveal the old rivets are still tight. In all actuality, this AD is complied with several times a year since its easy to accomplish with the access panel off and I've been checking it regularly every time I'm in there for one thing or another.

The clincher is, I can actually see movement between the inner and outer ring of one of the bearings when light is shined on it just right. I'm resigned to the fact the tail will have to come off for a third time. Just interested if anyone is out there with some insight about this that might minimize my chances of having to take this dang thing apart a fourth time.

[Zach Grant L1011jock]

Yes, and Yes. There are two possibilities here. First is the bearing is defective, and we have seen that, but more probably is the ID/OD of the torque tube vs the inner bearing race ring is not to spec. The tubes vary in OD significantly, and this was fixed at the Piper factory in original assembly by using some Locktite sleave seal between the two parts to take up the slack. Though it is not anywhere in the instructions, this is a legitimate way to eliminate the loose fit. Unfortunately the only fix here is to start by disassembling the tail again, but before you do, just take the tailcone off and verify where the play is so you know what you are looking at WRT getting a new bearing or not.

Zach

[Daniel Haumesser]

Zach, thats exactly the track I was on, thanks! I didn't want to mention the Loctite because I wasn't sure how legitimate its use was and didn't want to start a long discussion about weather its proper to use it in this applicattion or not.

I narrowed the looseness down to one of the new bearings. Removed it, reinstalled one of my original 1960 bearings that I removed (because it was 55 years old, not because it was loose: talk about going full circle). Then at reassembly I used Loctite 660 on all the places I thought may contribute to loseness, weather I thought it needed it or not. Between the torque tube and inner bearing race ring, between the outer bearing race ring and bearing block, also the inboard torque tube bearing block on each stabilator. Loctite 660 was recommended by the folks at Heritage Aero and works splendidly. The thing to remember is that you need to heat it to get it apart again (heat gun works well), so don't use it on places you can't get heat to (like the outbord torque tube bearing blocks in the stabilator). Things are tight again for now and I'm confident it will stay that way until I get the gumption to pull the trigger on a new torque tube and Australian horne.

Dan