[Boot Hill]

"Boeing still doesn't have much composite material in primary structures like the vertical tail."

The vertical stabilizer of Boeing's 777 is composite.

--Boot Hill

[RandyRep]

The skins AND the spars? Or only the skins? Big difference, obviously. I don't know if the Airbus spars are composite or not - perhaps none of them are? The spars are primary structure, as are the attach flanges.

You said something about a chunk of titanium in place of the composite in an earlier post. Titanium weighs quite a bit more than aluminum and composite for equivalent loads and temperatures. Titanium is used when you need a high-emperature capability (but not as high as steel) but want to save weight over steel. Aluminum is only 10-15% heavier than carbon-fiber composites for equal loads and temperatures. However, aluminum yields plastically and fails gradually while composites yield quickly and fail quickly - so aluminum as a much better choice for low temperature primary structure.

[Pukin Dog]

The point in question, is the stress point where the tail attaches to the fuselage, which in the 777, you have much, MUCH more plain old steel, than you have in the AirBus. It does not matter how much composite is in the tail itself, only where the pieces come together.