Q. During a Chandelle, your student has the proper high pitch attitude at the 90 degree point but loses it before finishing the maneuver at the 180 degree point.
What is wrong and how are you going to correct the problem?

A. Your student probably has not continued to increase back elevator pressure after reaching the 90 degree point.  Remember, the airspeed is continuing to decrease, resulting in a decrease in control effectiveness.  If the back elevator pressure remains constant after reaching the 90 degree point, at about the 135 degree point, the pitch attitude will start to decrease as the elevator becomes more less effective.  More back elevator pressure will have to be applied from the 90 degree to the 180 degree point to maintain the high pitch attitude.  Since the airspeed is continuing to decrease, more control deflection of the elevator will be necessary to get the same response, hence, more back elevator pressure is required to maintain the same attitude throughout the second half of the maneuver.