Manufacturing problems always end up on the designer’s desk
A designer of light aircraft was asked by an aircraft builder to design a single turbo prop aircraft, which was to be used for an air ambulance service between small islands off a coastal area. The aircraft was designed and then built by aircraft manufacturers.
Following delivery, the end user discovered small cracks in the hull of the aircraft. The aircraft was repeatedly returned to the builder for repairs, but the cracks continued to reappear on the hull. Eventually, the end user decided to claim against the manufacturer for supplying a defective product.
In turn, the manufacturer claimed that there was nothing wrong with the build quality of the aircraft, but rather that it had been designed badly. The designer was therefore brought into the proceedings as a third party defendant (along with various other parties including the propeller manufacturers and the hull manufacturers). Upon investigation, it became apparent that the cracks were caused by excessive vibrations in the hull.
Various theories for the vibrations were considered, but the most likely explanation was that the propeller was at fault due to unforeseen frequency resonations. This was something that the designers had considered and tested for, and they provided their calculations. However, as the hull was a completely new design, it did not resonate as had been predicted. Therefore, it was clear that the designer had not been negligent in the provision of his service to the manufacturer. Furthermore, there were certain reservations concerning both the weld quality of the hull by the manufacturer and the actual build quality of the hull material itself.
ITIC defended the designer successfully.