On July 19, 1989, United Airlines Flight 232 was cruising blandly along on autopilot at thirty-seven thousand feet a seven-foot number one fan disk broke into two big pieces, unleashing a sleeting storm of metal parts which severed the planes unprotected hydraulic lines—a "design flaw" in the DC-10. Flight 232 crashed, killing 112 of the 296 onboard. According to author Laurence Gonzales, the titanium fan disk, known as #00385, had a "deadly flaw," a "fatigue crack" possibly due from stresses induced in the disc during manufacturing in 1971.

Gonzales writes:

Every time an engine bearing fan disc 00385 was started, the crack grew a bit more, elongating outward from the bore toward the rim and the dovetail slot where the number 10 blade was attached. When the fatigue crack had grown to about one inch long and half an inch deep, the disk was ready to let go on the next flight. That flight took place July 19, 1989.

Fan disc 00385 received fluorescent penetrant inspection in 1972, 73, 76, 82, and 88. When Gonzales asked Nicholas Cherolis, an engineer for General Electric, if someone should have seen the crack in 00385, he said, "Ah. That's the tragic thing. Somebody's probably losing sleep over that."

Possible Preaching Angles: (1) Integrity; Character—The "fatigue flaws" in our character will also lead to our downfall. (2) Rest; Sabbath—Our literal "fatigue flaw"—that is, our inability to get rest—will lead to cracks in our lives.