Install the elevator.
With the under side of the fuselage and the under side of the elevator facing up, glue the two pieces together.
Make sure the two pieces are fully seated to each other. (This step is wrong. Don
’
t install the lower
horizontal fuselage here. Please install the lower fuselage after the landing gear installation.)
If so, squareness should be really close, double check with a tape measure by measuring from elevator
tips to the wing tips.