Taiwan's Aviation Safety Council finds undetected poor repair work was to blame for China Airlines crash in 2002
Taiwan's Aviation Safety Council (ASC) has determined that the 2002 crash of a China Airlines (CAL) Boeing 747-200 was caused by structural breakup in midair. According to the final accident report, "radar data indicated that the aircraft experienced an in-flight breakup at an altitude of 34,900 feet, just before it reached its [intended] cruising altitude of 35,000 feet".
The breakup began with progressive failure "in the aft lower lobe section of the fuselage" starting from a fatigue crack that had propagated unseen beneath an improperly conducted tailscrape repair, says the ASC report. All 206 passengers and 19 crew perished in the 25 May 2002 accident when the wreckage plunged into the Taiwan Strait just off the main island. At the time of the accident the aircraft was completing its climb out from Taipei international airport bound for Hong Kong.
The 1m long metal fatigue crack believed to have begun the breakup process started with an event on 7 February 1980, when "the accident aircraft suffered a tail strike occurrence in Hong Kong". The aircraft was ferried back to Taiwan on the same day, unpressurised, and a temporary repair was conducted the day after. A permanent repair was conducted between 23 and 26 May. The report says: "The permanent repair of the tail strike was not accomplished in accordance with [Boeing instructions]...and the repair doubler did not extend sufficiently beyond the entire damaged area.
"Maintenance inspection of B-18255 did not detect the ineffective 1980 structural repair and the fatigue cracks that were developing under the repair doubler, "it says. "The crack would still not be detected if external high frequency eddy current had been used for structural inspection." The ASC has recommended that "a more effective non-destructive structural inspection method should be developed".
The report criticises CAL for not keeping proper maintenance records. The airline says it has "spared no effort" to improve its maintenance operations in recent years.
DAVID LEARMOUNT / LONDON
Source: Flight International
