Karatoo J6 alert...........................................

[Guest Maj Millard]

I'm currently undertaking the repair of a J6 Karatoo wing that was damaged during Cyclone Yasi. The wing is ribstiched in the normal fashion, and externally everything looked normal. Once inside the wing however it became pretty obvious that all the internal rib stitching has dissappeared !!...gone ...not evident !!....ratted away !

 

There is evidence of rodentia droppings and assorted nesting trash, so I suspect the said rodentia have found the rib stitching cord to their dietary liking.

 

I have read of this occuring before, and I would highly recommend that all wood winged ribstitched wings be checked closely internally, at each inspection, to ensure the stitching is still sound.

 

This particular aircraft was prev GA registered as VH-CUA, and spent a good part of it's life in the Wilsons' Prom area of Vic, before being purchased by a NQld pilot. It is hard to accertain wether this has been like this for a long, or short period of time.

 

Ribstitching helps retain the adhesion of fabric to wing ribs, which in turn assures that the required airfoil shape of the wing is maintained. In some cases it can also add some structural strength to the wing itself. If the fabric separates from the wingribs in flight, it can adversley change the shape of the airfoil and possible ruin your day big time.

 

The chances of it occurring simitainesly on both wings is remote. It is more critical on a wing with an adverse under camber..I will send a defect report to the RAAus on this, to bring this to the attention to all Karatoo users.................................Maj...