AARON KARP / WASHINGTON DC
Boeing will provide a kit by mid-2004 to modify the elevator control systems of the 148 McDonnell Douglas DC-8s in service, following recommendations from the investigation into the crash of an Emery Worldwide DC-8 in February 2000.
In a report published last week, the US National Transportation Safety Board recommended that Boeing be required to redesign DC-8 elevator control tab installations after concluding that an elevator control tab, disconnected as a result of maintenance failures, caused the DC-8 freighter to crash shortly after take-off from Sacramento, California, killing all three crew.
"The probable cause of the accident was a loss of pitch control resulting from the disconnection of the right elevator control tab caused by the failure to properly secure and inspect the attachment bolt," says the NTSB. The safety board adds that Boeing should redesign DC-8 elevator control tabs so that any control tab disconnecting from its pushrod does not lead to catastrophic failure.
Due to this "improper" maintenance, says the NTSB, the bolt "migrated out of the [crank] fitting, allowing the control tab to disengage from its pushrod and shift to a trailing edge down position. When the aerodynamic forces increased as the aircraft accelerated during the take-off roll, the right elevator control tab crank fitting contacted the disconnected pushrod, restricting that control tab's further trailing edge up movement and leaving it in an extreme trailing edge down deflection."
Source: Flight International
