Aloha 243 — Corrosion and Fatigue Tore the Roof Off a 737 in Flight

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.