*  There was a SAFETY ALERT, SA-15-16/1, issued for stiffening the rear fiberglass spars of the horizontal stabilizers. A 165 hp Lightning, testing ABOVE VNE (180knt) experienced flutter. Arion's investigation found that the vendor producing the stabs did not use the correct 10 oz cloth. The rear insert calls for 6 layers of 10oz glass (7500 series). The 7500 series is a thick, plain weave, E glass that is 9.64oz in weight. Other areas of the aircraft use a 7781 series E glass for skins which is commonly referred to as 10oz glass. This is 8.71oz in weight and a fine weave.

    Horizontal Stabs produced prior to 3-2015 were at least 1/8” thick and clearly of a heavy weave e-glass. Stabs produced after 3-2015 were 1/16th inch thick and a fine weave. The 7781 has much higher breaking strength in sheer or tension but lacks the stiffness in the hinge line application that the 7500 series provides.

***The fix is to Laminate 6 layers to each horizontal stab of 7500 series E-glass. The laminate should run from the lower skin up the spar and under the hinge line, and go from root to tip. If done correctly the glass will run off the upper hinge line and lower skin slightly. Any 24 hour structural epoxy or vinyl ester maybe used. Epoxy’s such as AeroPoxy or Fiberglast System 2000 work well.

*  The hinge pictures show the closeness of the hinges to the rear stiffener. Adding another 1/16" is doable but I will need to redo the metal hinge on the stab side and trim them back to fit. My concern is the closeness of the screws to the edge. It is also an area I had DONE!

*  Otherwise I have been having fun doing brake lines, adding landing light pockets in the wings, and trial fitting the flaps to the wings and wondering where the final flap hinge will mount to the fuselage.