#TITLE_ALTERNATIVE#

• Main Author: S. SYAHIED FAUZY (NIM : 13606056); Pembimbing: Dr. Djarot Widagdo (ITB); Dr. Tatacipta Dirgantar, M.
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/16510
• Institution: Institut Teknologi Bandung

Boeing 737-400 PK-GWQ experienced a hydraulic loss just before the flaps were operated on a flight from UPG to BIK on January 15, 2010. The aircraft successfully landed but when in the middle of the runway, nose wheel steering couldn’t be operated. The crew found that the ground spoiler actuator has failed and caused the hydraulic fluid <br /> <br /> <br /> <br /> come out of the actuator. Spoiler actuator housing has broken into two parts on the thread area which is connected to the actuator nut. Actuator failed at 43,453 FH or 31,752 FC (Time Since New) and has never been removed before. The failed spoiler actuator was investigated to determine the root cause of failure. To support the analysis, visual <br /> <br /> <br /> <br /> inspection, stereomicroscopy, chemical analysis, fractography, metallography, hardness testing, and load-stress analysis were conducted. Based on chemical test result and hardness testing, this actuator housing is made from Aluminum Alloy 7075-T73. The evidence showed that the fracture was initiated from thread root and propagated radially. Beach mark was clearly observed at fractured surface as indication of fatigue failure. Multiple crack and small area of final fracture indicate that stress concentration is relatively high and occur at low stress. Metallographic examination showed that the thread is manufactured by machining. Compared to thread manufacturing by forging process, it has lower fatigue strength and has higher stress concentration. Load analysis showed that the dominant load comes from the hydraulic actuator. Stress analysis concluded that the weakest area is at the thread root between the first and the second thread. Those areas coincide with the location where the fracture was found. <br /> <br /> <br /> <br /> Component manufacturer are expected to modify geometry and manufacturing process of housing thread to reduce the level of stress concentration at the thread root area. Aircraft <br /> <br /> <br /> <br /> maintenace company is expected to be aware of this component at 25.000-32.000 FC due to the failure began in a location that is difficult to be detected.