Japan's Aircraft Accident Investigation Commission officially concluded that the rapid decompression was caused by a faulty repair by Boeing technicians after a tailstrike incident during a landing at Osaka Airport in 1978. The rear bulkhead of the plane had been repaired with an improperly installed doubler plate, compromising the plane's airworthiness. Cabin pressurization continued to expand and contract the improperly repaired bulkhead until the day of the accident, when the faulty repair failed, causing a rapid decompression that ripped off a large portion of the tail and caused the loss of hydraulic controls to the entire plane.