What happened
During the extension of the landing gear for touchdown, the flight crew reported experiencing a loud and very noticeable jolting of the aircraft. Shortly after this event, they observed that a portion of the right main gear had punctured the upper surface of the right wing. The crew subsequently declared an emergency and completed an uneventful landing.
The investigation
An examination of the aircraft revealed that the right main gear actuator support link, part number 65-19657-5, had become corroded and failed. Following this failure, the outboard end of the main gear actuator beam punctured the upper wing panel. Additionally, a hydraulic line was severed, which disabled the 'A' hydraulic system.
Findings
Maintenance records from the previous aircraft owner erroneously indicated that in 1971, the failed part had been replaced with a newer link assembly, part number 19657-11. This newer assembly did not require inspection. Consequently, the required inspections specified in Airworthiness Directive 68-17-01, regarding the failed link, had not been complied with by the new owner. Boeing had issued a service bulletin (727-32-306) which recommended that link assemblies with part number 19657-5 (as well as -4, -8 & -13) be removed from service and discarded.