Investigation Summary
Ten minutes into the climb out of Shanghai, the flight crew heard an explosive sound from the lower middle section of the aircraft. This was the rupture of a high-pressure air bottle used for the emergency braking system. The force of the rupture was sufficient to sever 13 hydraulic system tubes and 2 emergency air brake tubes. This resulted in a total loss of hydraulic pressure, rendering the flaps and normal braking systems inoperative. The captain attempted to use backup hydraulics, but these had also been compromised by the initial rupture. During the emergency return, the crew faced a flaps-up landing, which necessitated a significantly higher approach speed. Compounding the situation, the damage to the air lines meant the emergency pneumatic brakes were also unavailable. Notably, the captain did not inform the cabin attendants that the aircraft was making an emergency landing, instead describing it as a 'minor issue' and stating they were simply returning to Shanghai. This lack of communication contributed to panic among passengers during the high-speed touchdown and subsequent overrun. The aircraft touched down fast on Runway 36 and, unable to decelerate within the available distance, overran the runway and stopway. The airframe sustained substantial damage as it came to rest in a ditch, but all 124 occupants survived the subsequent evacuation.
Final Conclusions
The investigation concluded that the primary cause was the rupture of the emergency brake air bottle due to corrosion and fatigue cracking. The bottle, constructed of 41xx steel, had developed six cracks, the largest of which was 1.9mm in a section only 2.3mm thick. These cracks were attributed to faulty production. The rupture caused extensive collateral damage to the aircraft's hydraulic and pneumatic lines, leaving the pilots without flaps or brakes. While the investigation noted that the copilot failed to notify the captain that the air bottle pressure gauge had dropped to zero, and the captain chose not to dump fuel to reduce landing weight, the final report focused on the mechanical failure and the lack of X-ray inspection requirements in the maintenance manual that might have detected the corrosion.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
57-year-old male
Systems & Failure Modes
Emergency Brake Air Bottle
A high-pressure vessel designed to provide pneumatic braking if hydraulic systems fail. Its rupture in this case acted like a localized explosion, destroying nearby lines.
Hydraulic System
The DC-8 uses hydraulic pressure for flap actuation and wheel braking. The rupture severed both the primary and backup lines, leaving the aircraft in a 'clean' (flaps up) configuration with no stopping power.
Interesting Facts
- 01The aircraft was a Douglas DC-8-61 manufactured in 1971 and had received maintenance just 13 days before the incident.
- 02There were 124 people on board, consisting of 113 passengers (104 of whom were Japanese) and 11 crew members.
- 03The air bottle rupture severed 13 hydraulic tubes and 2 emergency air brake tubes.
- 0439 people were injured during the runway excursion and evacuation; there were no fatalities.
- 05The captain was a highly experienced veteran with 14,862 flight hours and was the DC-8 Flight Crew Manager.
- 06The air bottle was made of 41xx steel and failed due to corrosion-induced cracking that was not detectable by standard visual maintenance checks.
Safety Actions & Advisories
Fleet-wide X-ray Inspections
The Japanese Ministry of Transport ordered Japan Airlines to conduct X-ray inspections of its entire DC-8 fleet to detect internal corrosion in air bottles that visual inspections could not identify.
Maintenance Manual Revision
The investigation highlighted that the existing maintenance manuals did not require X-ray inspections for these components, leading to updates in scheduled maintenance procedures.
Known Controversies & Unanswered Questions
Pilot Decision Making
Reference ↗Investigators and experts debated the captain's decision to land immediately without dumping fuel, which increased the landing speed, and the copilot's failure to report the zero-pressure reading on the air bottle gauge.