China Airlines Fire Possible Cause
Flight 120 Landed, an Inferno Erupted in Japan and 165 People Escape
The smoke is still smoldering and another aircraft has had a catastrophic accident. However, this one should not take long to evaluate. Here is why.
The History
Recently a Jetblue Airbus caught fire while on the ground near the hanger. Only mechanics were onboard however, the engine and wing suffered severe damage. Preliminary results are that there was an “electrical short…in a fuel vapor environment…” March 3rd 2001 a Thai Airways B-737 blew up on the ground at the gate because of an “electrical short…in a fuel vapor environment…” On May 11th 1990 a one year old Philippines Airlines B-737 blew up on the ground preparing for take off because of an “electrical short…in a fuel vapor environment…” Today China Airlines flight CI-120 was on an international flight from Taipei Taiwan to Naha Okinawa Prefecture in Japan. The flight was, by all means, normal until the last few minutes at the gate when it suddenly blew up. Already what probably happened is well known in aviation circles and an electrical short…in a fuel vapor environment…” is considered the prime culprit.*
The Facts
Flight CI-120 was a Boeing B737-800 Serial Number 30175 (Registration B-18616 built in 2002) that departed RCTP at 08:15 and arrived OKA at 10:31 (local time.) The one hours 16 minute flight had 157 passengers and 8 crew on board including 2 infants. 8 minutes after landing at Naha airport OKA (ICAO identifier ROAH) the flight arrived at parking stand #41. Several seconds later the flight burst into flames.
According to witnesses, the ground crew noticed fuel coming from under the center of the aircraft. It is known that the Captain ordered an emergency evacuation, the cabin crew (having doors still armed) immediately initiated the mass departure and all persons got out safely. Several minutes later there was an explosion under the #1 engine followed by an explosion under the #2 engine that completely engulfed the center section of the aircraft.
Preliminary Considerations
Incidents like this are not infrequent. “Extensive research…revealed that dangerous conditions in fuel tanks occur more commonly than had been believed, and that there are numerous potential sources of energy to ignite fuel tank vapors,” as told by National Transportation Safety Board acting Chairperson Carol Carmody in an August 8th 2001 NTSB Advisory Bulletin.
TWA 800, the official cause of this accident was “…an explosion of the center wing fuel tank resulting from ignition of the flammable fuel/air mixture in the tank. The source of ignition…was a short circuit…associated with the fuel quantity indication system.” This was the first official notification (in modern aircraft) of an “electrical short… in a fuel vapor environment!”
The official causes of both the Thai Airways and Philippines Airlines Boeing B-737s accidents were electrical shorts in fuel vapor environments. Numerous other accidents, having the same grounds, have happened over the years.
Examining the footage provided by Japanese Television FNN the trained eye will notice several very important things.
- The engine did not explode. The explosion came from under the engine (on the ground) where there was a fuel environment. An ignition source (the fire above) caused the fuel pool to ignite.
- The largest explosion was on the aircraft left side under the left center of the aircraft near the aft fuel boost pumps.
- The Commonwealth of Australia, following the US FAA, issued an Airworthiness Directive AD/737/226 for this model of Boeing 737-800. “This Directive requires, for some aeroplanes, installation of screws and spacers to secure the wire bundles for the aft fuel boost pumps** of the main fuel tanks….This action is necessary to prevent electrical arcing in a fuel leakage zone, which could result in an uncontrolled fire.”
- The aircraft’s left aft fuel boost pump is near the left aft wing root (where the left wing and main part of the aircraft body come together.)
- The COA, referencing the US FAA, issued Airworthiness Directive AD/B737/119 Amdt 1 “Since the issuing of FAA AD T98-11-52, the FAA has received additional reports of severe wear of fuel boost pump wiring on model 737 series aeroplanes….the FAA has expanded the inspection requirements to include aircraft that have accumulated between 20,000 and 30,00 hours total time in service.” While not specific for the accident model B-737, the airworthiness directive indicates that the problem has existed in all models of Boeing B-737s for some time.
- This aircraft had an estimated 14,000 hours prior to the flight.***
The preliminary information shows a classic problem that has existed for some time. The first evidence was with TWA 800 but today’s accident seems to follow the same pattern: electricity, electrical short circuits and a flammable fuel environment. Fortunately for all no loss of life occurred.
** Boost Pumps are the electrical pumps that move the fuel from the fuel tanks through fuel lines to the engines.
* Statements from NTSB Accident Database, foreign accident investigations and US State Department Notifications.
*** Based upon extrapolated data from the July 13th 2007 inspection of the #1 engine.
