Checks 'might have prevented' crash

Weakness suspected of causing CAL 747-200 loss was not spotted when routine corrosion tests were neglected

Adherence to a standard maintenance programme might have prevented the May 2002 in-flight structural failure of a China Airlines (CAL) Boeing 747-200 (B-18255), Taiwan's Aviation Safety Council (ASC) has now revealed. The ASC shows the airline failed to perform a raft of corrosion-prevention tests required under a Taiwan CAA-approved maintenance programme.

The ASC, still investigating the fatal crash, says that "at the time of the accident, there were 16 items overdue and not implemented". Another 13 scheduled inspections due in the late 1990s had also been performed late, the ASC says, one by more than a year.

The checks - mainly interior and exterior fuselage inspections, as well as wing and complete tailplane inspections - were due to be carried out at four-, five-, six- or eight-year intervals.

Of the 16 items not checked before the crash, eight were due in November 1999 and eight in November 2001. Of the 13 corrosion prevention and control programme items deferred, one due in November 1997 was eventually performed in December 1998, while the remaining 12 were due in November 1998 but were carried out in January 1999. The accompanying table shows the discrepancy between the four-yearly schedule and the actual performance of the corrosion prevention and inspection to the interior of B-18255's fuselage bilge. The last check was delayed by 13 months.

The ASC has not yet definitely linked the late or incomplete checks to the crash, but it reported earlier in the investigation that studies of some recovered aircraft wreckage indicated there were pre-existing cracks in the rear fuselage. The agency expects to publish a final report before the end of the year, but a draft of it has already been sent to interested parties.

All 225 people on board the 22-year-old 747-200 died in the 25 May 2002 crash. On a flight from Taipei to Hong Kong the aircraft broke up 20min after take-off as it was nearing its cruising level, and four main sections were recorded on radar falling into the Taiwan Strait. When it released a factual summary of events last year the ASC said the investigation team had found "no evidence in the areas of air traffic services, weather, flight operations, and powerplant that can be related to the causal factors of this accident...The investigation team also found no evidence of fire, smoke, explosives, external forces or any security related matters that are relevant to this accident."

NICHOLAS IONIDES / SINGAPORE

Source: Flight International