The fuselage of the Aloha Boeing failed, despite the fact that it was designed and built to well proven rules. Why? The whole industry had become complacent about maintenance and particularly about the durability of old aircraft. To put this in perspective the accident aircraft was nineteen years old, older no doubt than the cars driven by most of the passengers. The aircraft had operated for 35,496 hours, in other words it had actually been up in the air for a total of four years. The aircraft had taken off 89,680 times, that means each flight had averaged only about 25 minutes. Every 25 minutes the skin, the frames and the joints had been stretched as the fuselage had been pumped up to maximum pressure. How could the airlines and their mechanics have become complacent about their planes while treating them like this?

Boeing was concerned about its old aircraft in general terms, it too was complacent about the fuselage. This was because of a naive faith in a concept called the "lead crack". Boeing engineers believed that if the fuselage did crack anywhere, a single "lead crack" would grow along the skin until it reached a fuselage frame, then it would turn at right angles and a triangular shaped tear would blow out and safely dump fuselage pressure. Boeing is a close knit company and when an idea like this takes hold it becomes accepted as gospel. It went unchallenged by most of the FAA. The British and Australian authorities never accepted the concept but needed an accident to prove them right.(Lessons from Aloha: Martin Aubury)