NASA-LLIS-0856

Abstract

<strong>Description of Driving Event:</strong> <br>The SOFIA B747 upper rudder was dropped after it was removed from the tail of the aircraft and was in the process of being placed on a flat bed trailer. <br>Maintenance personnel attempted to rotate the removed rudder from the vertical to the horizontal position. This task was performed without the use of a holding/transport fixture as defined within the specific task job card and utilizing only two of the four attach points called out in the written procedures. Prior to removal, the procedures were reviewed and found adequate to perform this task. While the procedures addressed the equipment and the process for removal of the rudder, they did not address the process beyond installation of the vertical rudder on a dolly. Though telephone calls were made in an attempt to locate equipment required by the procedures, there was none available when the decision was made to proceed with the rudder removal. The production supervisor admitted responsibility for the decision to proceed without all of the equipment required by the procedures and he proceeded to transition the rudder from a vertical to a horizontal position. <br>The transition was attempted by unfastening the two harness support brackets on one side of the rudder. As the crew began the transition, the loading was multiplied by approximately 800 lbs. of counterweights on the rudder's leading edge, a condition for which the sling assembly and attach points were not designed to carry. Of the three bolts at the point of failure, one bolt stripped the threads on exit, another pulled the attachement receptacle through and out, and the third bolt pulled the attachment receptacle and surrounding structure loose from the rudder.