At 13:46 Hawaii time on 28 April 1988, Aloha Airlines Flight 243 — a 19-year-old Boeing 737-297 climbing through 24,000 feet between Hilo and Honolulu — suffered an explosive decompression in which roughly 18 feet of the upper fuselage skin and structure peeled away in flight; chief flight attendant Clarabelle “C.B.” Lansing was swept overboard and never recovered, eight people were seriously injured, and the cause was not a bomb, a bird, or pilot error but fatigue cracking and crevice corrosion that had linked along a cold-bonded lap joint until the cabin tore open like a tin. The aircraft, registration N73711, had flown about 89,680 pressurization cycles — among the highest of any 737 in service — on Aloha’s short inter-island hops, and each cycle had loaded the joint that failed.
The fracture began at the longitudinal lap joint along stringer S-10L, on the upper row of rivets where the upper fuselage skin overlaps the lower. The joint had been assembled with a cold-bonded epoxy-scrim adhesive intended to share the pressurization load across the bonded area rather than through the rivets alone. When that bond disbonded — a known defect in early 737 production — salt-laden humid air entered the gap, crevice corrosion attacked the faying surfaces, and the entire hoop load funneled into the rivet holes. There, the countersunk “knife-edge” rivet design left a thin, sharp lip of metal at each hole, an ideal site for fatigue cracks to initiate. Cracks formed at many adjacent holes at once.
This was multiple-site damage: not one large crack growing slowly toward a detectable size, but dozens of small subcritical cracks, each individually below the inspection threshold, growing in parallel along the rivet row. When the ligaments between them failed, the cracks linked instantaneously into a single running fracture and a “flap” of fuselage unzipped. The National Transportation Safety Board, in report AAR-89/03, fixed the probable cause as the failure of Aloha’s maintenance program to detect the disbonding and fatigue damage at S-10L — a detection failure, not merely a structural one. The metal had behaved exactly as fracture mechanics predicted; the system meant to catch it had not. Inspections ran at night under poor lighting, crews were untrained to find disbonds, a Boeing service bulletin and an FAA Airworthiness Directive on the books had a scope too narrow to mandate the joint that failed, and a passenger had seen a crack while boarding and said nothing. Aloha 243 became the founding case of the aging-aircraft era in commercial aviation.
At about 18:30 on 27 March 1980, in the Ekofisk oil field of the Norwegian North Sea roughly 320 km east of Dundee, the semi-submersible platform Alexander L. Kielland lost one of the five columns supporting its accommodation deck, listed heavily within seconds, and capsized completely within roughly twenty minutes; 123 of the 212 people aboard died, making it the deadliest accident in Norwegian offshore history. The cause was not the storm, though a gale was blowing. It was a fatigue crack that had grown from a 6 mm fillet weld — the weld attaching a hydrophone fitting to one diagonal brace — until that single brace, called D-6, parted and threw an overload onto the remaining structure.
The Kielland was a Pentagone-type rig: a pentagonal pontoon ring carrying five vertical columns, each column tied into the truss by a web of horizontal and diagonal tubular braces. It had been built in France and delivered in 1976 as a mobile drilling unit, but by 1980 it was working as a “flotel,” a floating accommodation block bridged alongside the Edda 2/7C production platform and housing oilfield crews off shift. Column D was held to the frame by six braces. The disaster turned on the fact that those braces were not redundant: when D-6 failed, the load it had carried redistributed onto the other five, which overloaded and tore away in rapid succession by plastic collapse. Column D, no longer restrained, broke off. With a fifth of its support gone, the rig flooded asymmetrically, heeled past recovery, and turned over.
The fracture origin was traced with forensic precision by the Norwegian commission of inquiry. On brace D-6 a small flange plate carrying a hydrophone — a sonar instrument used in position-keeping — had been welded on with a poor-quality 6 mm fillet weld during fabrication. The weld had bad penetration, a poor bead profile, and lamellar tearing in the underlying plate; cracks were present essentially from the day the rig was built. Cyclic wave loading drove a fatigue crack around the circumference of that weld and then into the wall of the brace itself. By the night of the capsize the sound steel remaining across the D-6 section was less than half its original area. The brittle, salt-painted fracture surfaces later showed beach marks recording years of crack growth that no inspection had ever caught.
The evacuation compounded the structural failure into a mass casualty: with the rig already heeling toward 30 to 35 degrees, most lifeboats could not be released from their falls under the list and wind, and one came down upside down. The commission’s 1981 finding was unambiguous — a high-cycle fatigue fracture, initiated at a defective non-structural weld, propagating through a structure with no redundancy to absorb the loss of one member.
At 15:16 on 19 July 1989, cruising near 37,000 feet over north-central Iowa, the tail-mounted No. 2 engine of United Airlines Flight 232 — a McDonnell Douglas DC-10-10 carrying 296 people from Denver to Chicago — disintegrated without warning; 44 minutes later the crippled airliner broke up on landing at Sioux Gateway Airport, killing 112 and leaving 184 alive. The cause was not bird strike, pilot error, or fire. It was a single high-cycle fatigue crack that had grown for years from a metallurgical defect buried in the bore of one titanium fan disk, until the disk burst and threw high-energy fragments through every hydraulic line on the aircraft at once.
The disk was the stage-1 fan rotor of a General Electric CF6-6D turbofan, a forged Ti-6Al-4V component roughly a metre across spinning at takeoff and climb power. Embedded in its bore, dating to the original titanium melt, was a “hard-alpha” inclusion — a brittle, low-ductility region where the casting had absorbed roughly 2.07 percent nitrogen by weight against a specified maximum near 0.02 percent. Sitting in the most highly stressed part of the disk, around a tiny cavity within it a fatigue crack initiated and crept outward, one spin-up and spin-down at a time, through some 17,000 flight cycles of revenue service.
Because the DC-10’s three independent hydraulic systems all routed lines through the tail in the arc swept by a bursting tail engine, the uncontained debris severed all three at once and drained every drop of fluid. The crew — captain Alfred Haynes, first officer William Records, second officer Dudley Dvorak, and off-duty check airman Dennis Fitch, who worked the wing throttles by hand — flew an aircraft with no working flight controls to a runway on differential thrust alone. The forensic verdict in NTSB report AAR-90/06 was unambiguous: a fatigue fracture from a hard-alpha inclusion, missed by six successive fluorescent-penetrant inspections, compounded by hydraulic architecture with no protection against a total loss. The survival of 184 of 296 was attributed almost entirely to the airmanship of a crew flying a configuration the manufacturer had never deemed survivable.