PA-22 Flap Bellcranks Cracked

[vas]

At annual we found cracks in the flap tie rod retaining fork of each flap bellcrank, left and right wing.

We found the bellcranks in stock at Univair and priced within reason. We got the old ones out of the wing through the inspection ports by detaching the mount brackets from the false spar.

When we install the new bellcranks should we shim the considerable gap between the flap tie rod faces and the fork of the bellcrank? The reason we were examining the tie rods was to investigate what seemed to be excessive play in the flap position. Is it possible this play contributed to the cracks in the bellcrank forks?

Thank you.

Vas

[Allycat]

Is it possible you could post some images of the cracked part and gap in question?

Regards,
Allycat

[Steve Pierce]

Yes, it is a common problem. There is a specific counter sunk shanked screw or bolt depending on the bellcrank installed and the drawings show AN960-10 washers being installed to shim the bellcrank ears. The problem comes when people crank down on the fastener and do not shim it and it compresses the cast aluminum ears cracking them.

[PA-22/20-160]

Could the crack be tig welded?

[Steve Pierce]

I would not weld a cast aluminum part. Seen too many Scott brake cylinders that were welded and then cracked outside of the heat effected zone.

20160830_072441.jpg

[vas]

Thank you, Steve. The new bellcranks from univair arrived this morning and were installed with shim washers as per your note above. The flaps deploy and retract like butter, with only a little residual play at the flap hinges. I will post a photo of the cracked bellcrank tomorrow after I clean it up.

Vas