Originally Posted by
Parapunter
The JAL accident IIRC was caused because the boeing engineers who repaired the aft pressure bulkhead used only one line of rivets instead of two & the pressurisation cycles led to stress cracking & eventual explosive decompression which ruptured all the hydraulic systems thus crippling the crews ability to fly the airplane.
Worst of all, the plane flew on for a while & in the wreckage, the rescuers found all kinds of final notes for loved ones that the pax had time to write in the certain knowledge they were about to die. A horrible crash that one.
Despite having lost practically all of the vertical fin and with zero hydraulics Captain Takahama (a JAL 20 year veteran) and his crew managed keep the crippled 747 airborne for some 30 minutes by using engine power alone to control the aircraft.
Perhaps even more disconcerting is the fact that the aircraft flew on for 7 years after the completion of the improper repair. The then-president of JAL resigned his post shortly afterwards and JAL, also staying true to traditional Japanese values, later admitted warning signs that something was amiss with the aft area of that aircraft were ignored. Various JAL flight/cabin crew had reported 'whistling sounds' emanating from the tailcone for several years prior to the loss of flight 123, but no detailed maintenance follow ups on the tail section were ever performed.
The repair ,had it been correctly accomplished should have lasted 10,000 cycles by Boeing estimates. According to records, the JAL 747 was already 2,000 cycles beyond that figure.