On August 20, 2007, a Boeing 737-800, registered B18616, operated by China Airlines flight CI120 took off from Taiwan Taoyuan International Airport on a regularly scheduled Flight 120 of the company, and landed at Naha Airport.
At about 10:33, immediately after the aircraft stopped at Spot 41, fuel that was leaking from the fuel tank on the right wing caught fire and the aircraft was engulfed in flames.
There were 165 people on board China Airlines flight CI120, consisting of the Captain, seven other crewmembers, and 157 passengers (including two infants). Everyone on board was evacuated from the aircraft and there were no dead and wounded. The aircraft was badly damaged and destroyed by fire, leaving only part of the airframe intact.
10:26:52 The Aircraft landed (touched down) on Runway 18.
10:27:14 The Aircraft began turning left on the runway to enter Taxiway E6.
10:27:49 The No. 5 slat began retracting while the Aircraft was in transit from Taxiway E6 to Taxiway A5.
10:28:09 The No. 5 slat retracted completely after the Aircraft entered Taxiway A5.
10:31:36 The Aircraft turned to the right to leave Taxiway A1 and aligned its nose with the Aircraft Stand Lead-in Lines for Spot 41.
10:31:57 China Airlines flight CI120 stopped (zero ground speed) in Spot 41
10:32:00 Engine shutdown procedures were performed for both engines.
10:32:44 A ground crew member switched on the interphone on the Aircraft’s nose.
About 10:32:53 Fire broke out somewhere in an area aft of the No. 2 (right) engine and spread to the right wing leading edge near the No. 5 slat and the apron surface below the No. 2 engine.
About 10:33 Several air traffic controllers (hereinafter referred to as “the Controllers”) the airport traffic control tower (hereinafter referred to as “the Tower”) saw black smoke and confirmed a fire on the Aircraft on the ITV monitors (showing images from the airport monitoring cameras).
10:33:05 The assistant maintenance engineer reported the fire breaking to the Captain over the interphone (saying, “Cockpit, Ground, Number Two Engine Fire!”).
10:33:42 Having received the fire report, the Captain visually confirmed himself black smoke and informed the cabin crew of the emergency situation, saying, “Attention! Crew On Station!”
10:33:52 The Captain of China Airlines flight CI120 instructed the cabin crew to prepare for an evacuation, saying, “Crew… uh… prepare for evacuation.”
10:33:58 The Controller (the coordinator) started simultaneous reporting of the fire over the crash phone*2 to the three relevant departments: the command room (hereinafter referred to as “the Fire Command Room”) of the No. 1 Naha Office of the Air Safety Foundation (hereinafter referred to as “the Airport Fire Station”) building, the Air Traffic Services Flight Information Officer (hereinafter referred to as “the Flight Information Officer”), and the Air Self-Defense Force Base Operations (hereinafter referred to as “the BOPS”).
10:34:12 The Controller reported the fire to the Aircraft.
About 10:34:24 Evacuation began with the first person on Evacuation Slide (hereinafter referred to as “Slide”) 3R4.
About 10:34:25 Slide 1L was deployed.
About 10:34:32 Slide 1R was deployed.
About 10:34:36 Slide 3L was deployed
About 10:34:37 Evacuation began on Slide 1R. About 10:34:47 Evacuation began on Slide 3L.
10:34:47 JTA Flight 602 (Boeing 737-400, registered JA8597) landed on Runway 18.
10:34:49 The APU fire extinguisher lever was pulled and rotated.
10:34:55 CVR came to a stop.
About 10:35 Two fire engines and one water truck (hereinafter referred to as “the airport fire engines”) of the Airport Fire Station left the garage. An off-duty staff of the Naha City Fire Department Headquarters, who was near the airport, reported the fire to the Headquarters office (hereinafter referred to as “The Naha City Fire Department”).
10:35:15 Simultaneous reporting over the crash phone ended.
About 10:35:42 Evacuation on Slide 1R was completed.
China Airlines flight CI120 : watch the video of the accident !source : Aviation Accident Database youtube channel ©
10:35:46 JTA Flight 602 made initial contact with the ground controller at Taxiway E4.
10:35:49 The ground controller cleared JTA Flight 602 to taxi to Spot 27.
10:35:55 The No. 2 airport fire engine (call sign “No. 2 Hoan Bosai”) called the Tower over the MCA (multi-channel access system) radio (saying, “This is No. 2 Hoan Bosai. Over”) (first recorded communication) but there was no response to the call. (During the time around this call, the airport fire engines were at a stop, facing JTA Flight 602, which was on its way from Taxiway E4 to Taxiway A3.)
About 10:35:58 Evacuation on Slide 3R ended.
About 10:36 Fire engines of the Fire Fighting Sub-squadron, Civil Engineering Squadron, Air Base Group, 83rd Air Wing, JASDF (hereinafter referred to as “the JASDF Fire-fighting Squad”) left the garage.
About 10:36:00 Evacuation on Slide 3L ended.
About 10:36:02 The First Officer began his escape through the right-hand side window of the cockpit using an evacuation assist rope.
About 10:36:06 Evacuation on Slide 1L ended.
About 10:36:11 The first explosion occurred on the right wing.
About 10:36:12 The First Officer, still on the rope, fell to the ground due to the blast of the explosion.
10:36:15 The Tower called the ANA No. 2 tug vehicle over the MCA radio. (Note: The ANA No. 2 tug vehicle was not in the group to communicate with the Tower.)
About 10:36:20 The Captain of China Airlines flight CI120 escaped through the right-hand cockpit window using an evacuation assist rope.
10:36:24 The No. 2 airport fire engine made the second call to the Tower over the MCA radio, saying, “This is No. 2 Hoan Bosai. Over.” There was no response to the call.
10:36:31 The ANA No. 1 tug vehicle called the Tower over the MCA radio.
About 10:36:54 The second explosion occurred below the right wing or around the bottom of the fuselage.
About 10:37 The Naha City Fire Department dispatched the first group of fire engines.
10:37:11 The third explosion occurred around the bottom of the Aircraft.
10:37:42 The ground controller instructed JTA Flight 602 (on Taxiway A2) to hold at the No. 4 stop line.
10:38:17 The Tower made the first call to the airport fire engines over the MCA radio, but there was no response to the call.
About 10:38:25 The No. 6 airport fire engine began discharging fire-extinguishing foam from a point aft of the Aircraft on the right side (in Spot 41).
About 10:38:26 The fuselage bent at around the wing location, and its tail portion touched the ground.
10:38:58 The No. 2 airport fire engine began discharging fire-extinguishing foam from a point forward of the Aircraft (in Spot 41).
About 10:39:48 The right wing tilted down and its tip slowly came in contact with the ground surface.
10:39:50 The Tower made the second call to the airport fire engines over the MCA radio, but there was no response to the call.
About 10:40 The Naha City Fire Department dispatched the second group of fire engines.
About 10:42 The JASDF fire-fighting squad’s fire engines began fire-fighting operations in Spot 41.
10:43:45 The Tower made the third call to the airport fire engines over the MCA radio, but there was no response to the call.
About 10:44 The Naha City Fire Department’s fire engines began fire-fighting operations in Spot 41.
10:57:28 The No. 5 airport fire engine (water truck) called the Tower over the MCA radio for permission to use the fire hydrant near the runway.
About 11:37 Fire-fighting operations of China Airlines flight CI120 were completed.
It is considered highly probable that the accident of China Airlines flight CI120 occurred through the following causal chain: When the Aircraft retracted the slats after landing at Naha Airport, the track can that housed the inboard main track of the No. 5 slat on the right wing was punctured, creating a hole. Fuel leaked out through the hole, reaching the outside of the wing. A fire started when the leaked fuel came into contact with high-temperature areas on the right engine after the Aircraft stopped in its assigned spot, and the Aircraft burned out after several explosions.
With regard to the cause of the puncture in the track can, it is certain that the downstop assembly having detached from the aft end of the above-mentioned inboard main track fell off into the track can, and when the slat was retracted, the assembly was pressed by the track against the track can and punctured it.
With regard to the cause of the detachment of the downstop assembly, it is considered highly probable that during the maintenance works for preventing the nut from loosening, which the Company carried out on the downstop assembly about one and a half months prior to the accident based on the Service Letter from the manufacturer of the Aircraft, the washer on the nut side of the assembly fell off, following which the downstop on the nut side of the assembly fell off and then the downstop assembly eventually fell off the track.
It is considered highly probable that a factor contributing to the detachment of the downstop assembly of China Airlines flight CI120 was the design of the downstop assembly, which was unable to prevent the assembly from falling off if the washer is not installed.
With regard to the detachment of the washer, it is considered probable that the following factors contributed to this: Despite the fact that the nut was in a location difficult to access during the maintenance works, neither the manufacturer of the Aircraft nor the Company had paid sufficient attention to this when preparing the Service Letter and Engineering Order job card, respectively. Also, neither the maintenance operator nor the job supervisor reported the difficulty of the job to the one who had ordered the job.