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Zenair CH701 & Savannah Rivets


vk3auu

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I have brought this matter to the attention of the RAA but nothing has been done yet.

 

I have a Zenair CH701 which as most people know is the aircraft that the Savannah has been copied from. A problem has developed around the upper brackets which attach the rudder to the fuselage' There are two extrusions which are attached to the rudder by 5/32" rivets, four at the top and four at the bottom. After a few years of operation, nearly always on grass strips, these rivets have worked loose, so I drilled them out and replaced them with 3/16 inch bolts.

 

At Narromine a couple of years ago, I inspected all the CH701 and Savannah aircraft. The rivets on a CH701 had almost pulled out on one side and the owner replaced them before he flew home. Several of the Savannahs showed signs that the rivets were starting to loosen as the paint was starting to show a small crack.

 

The same method of construction is used on the Zenair CH601 series. The problem is caused by the fact that these rivets are in tension and good design says that this type of rivet should only be used in shear.

 

Please have a look at this part of your aircraft carefully and rectify any problems. Don't just replace the rivets with more rivets, use bolts.

 

David Tanner

 

CH701 19-1877

 

 

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  • 4 weeks later...
  • 1 year later...

I have also raised this issue with the Zenair factory, but they dismiss it as a non event. It also applies to ALL the CH601's as they use a similar method of attachment of the rudder.

 

We either have rougher strips than they do, or we fly in rougher air.

 

David

 

 

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  • 2 years later...

just completed a 700 hr inspection of my Savvy, no sign of loose rivets, only a few working rivets on the aerodynamic fairing in front of the vertical stabiliser the 3/32 ones. the only rivets i have had to replace have been the blinds around the door cutout due to chaffing of the rivet heads down by the door seals.

 

 

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