Complex sentence: The program was delayed several times, at first due to underestimating the developmental complexity and manufacturing learning curve of the production composite construction, and later due to the technical difficulties of correcting a pitch damping problem and developing the stall-warning system.
Split into simpler sentences: The program was delayed several times, at first due to underestimating the developmental complexity and manufacturing learning curve of the production composite construction. And later due to the technical difficulties of correcting a pitch damping problem and developing the stall-warning system.