Irish Steve
31st Aug 2005, 18:34
This may be old new, if so, my apologies, it's only just been forwarded to me.
SCARY
"On May 25 2002, 1529 Taipei local time (Coordinated Universal Time, UTC 0729), China Airlines (CAL) Flight CI611, a Boeing 747-200 (bearing ROC Registration Number B-18255), crashed into the Taiwan Strait approximately 23 nautical miles northeast of Makung, Penghu Islands of Taiwan, Republic of China (ROC). The aircraft was on a scheduled passenger flight from Chiang -Kai-Sheik (CKS) International Airport, Taipei, Taiwan, to Chek Lap Kok International Airport, Hong Kong, China. All 206 passengers and 19 crewmembers sustained fatal injuries." "There are 6 finding related to the probable causes:
Based on the recordings of CVR and FDR, radar data, the dado panel open-close positions, the wreckage distribution, and the wreckage examinations, the ASC concludes that the in-flight breakup of CI611, as it approached its cruising altitude, was highly likely due to the structural failure in the aft lower lobe section of the fuselage.
The ASC found evidence of fatigue damage in the lower aft fuselage centered about STA 2100, between stringers S-48L and S-49L, under the repair doubler near its edge and outside the outer row of securing rivets. Multiple Site Damage (MSD), including a 15.1-inch through thickness main fatigue crack and some small fatigue cracks were confirmed.
Residual strength analysis indicated that the main fatigue crack in combination with the MSD were of sufficient magnitude and distribution to facilitate the local linking of the fatigue cracks so as to produce a continuous crack within a two-bay region (40 inches).
Analysis further indicated that during the application of normal operational loads the residual strength of the fuselage would be compromised with a continuous crack of 58 inches or longer. Although the ASC could not determine the length of cracking prior to the accident flight, the Council believes that the extent of hoop-wise fretting marks found on the doubler, and the regularly spaced marks and deformed cladding found on the fracture surface suggest that a continuous crack of at least 71 inches in length, a crack length considered long enough to cause structural separation of the fuselage, was present before the in-flight breakup of the aircraft.
The ASC found that the 15.1-inch crack and most of the MSD cracks initiated from the scratching damage associated with the 1980 tail strike incident in Hong Kong, which the repair was not accomplished in accordance with the Boeing SRM, as the damaged skin in that area was not removed (trimmed) and the repair doubler did not extend sufficiently beyond the entire damaged area to restore the structural strength.
Prior to the occurrence, the operator's maintenance inspection of B-18255 did not detect the ineffective 1980 structural repair and the fatigue cracks that were developing under the repair doubler. "
The full report can be found here (http://www.asc.gov.tw/asc_en/news_list_2.asp?news_no=194)
SCARY
"On May 25 2002, 1529 Taipei local time (Coordinated Universal Time, UTC 0729), China Airlines (CAL) Flight CI611, a Boeing 747-200 (bearing ROC Registration Number B-18255), crashed into the Taiwan Strait approximately 23 nautical miles northeast of Makung, Penghu Islands of Taiwan, Republic of China (ROC). The aircraft was on a scheduled passenger flight from Chiang -Kai-Sheik (CKS) International Airport, Taipei, Taiwan, to Chek Lap Kok International Airport, Hong Kong, China. All 206 passengers and 19 crewmembers sustained fatal injuries." "There are 6 finding related to the probable causes:
Based on the recordings of CVR and FDR, radar data, the dado panel open-close positions, the wreckage distribution, and the wreckage examinations, the ASC concludes that the in-flight breakup of CI611, as it approached its cruising altitude, was highly likely due to the structural failure in the aft lower lobe section of the fuselage.
The ASC found evidence of fatigue damage in the lower aft fuselage centered about STA 2100, between stringers S-48L and S-49L, under the repair doubler near its edge and outside the outer row of securing rivets. Multiple Site Damage (MSD), including a 15.1-inch through thickness main fatigue crack and some small fatigue cracks were confirmed.
Residual strength analysis indicated that the main fatigue crack in combination with the MSD were of sufficient magnitude and distribution to facilitate the local linking of the fatigue cracks so as to produce a continuous crack within a two-bay region (40 inches).
Analysis further indicated that during the application of normal operational loads the residual strength of the fuselage would be compromised with a continuous crack of 58 inches or longer. Although the ASC could not determine the length of cracking prior to the accident flight, the Council believes that the extent of hoop-wise fretting marks found on the doubler, and the regularly spaced marks and deformed cladding found on the fracture surface suggest that a continuous crack of at least 71 inches in length, a crack length considered long enough to cause structural separation of the fuselage, was present before the in-flight breakup of the aircraft.
The ASC found that the 15.1-inch crack and most of the MSD cracks initiated from the scratching damage associated with the 1980 tail strike incident in Hong Kong, which the repair was not accomplished in accordance with the Boeing SRM, as the damaged skin in that area was not removed (trimmed) and the repair doubler did not extend sufficiently beyond the entire damaged area to restore the structural strength.
Prior to the occurrence, the operator's maintenance inspection of B-18255 did not detect the ineffective 1980 structural repair and the fatigue cracks that were developing under the repair doubler. "
The full report can be found here (http://www.asc.gov.tw/asc_en/news_list_2.asp?news_no=194)