Aircraft Accident Investigation Report No. ACCID01/06
Aircraft Accident Investigation Report No. ACCID01/06
Aircraft Accident Investigation Report No. ACCID01/06
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CityU Professional Services Ltd<br />
Failure Analysis of a Towbar<br />
Department of Physics & Materials Science<br />
City University of Hong Kong<br />
The head assembly is made from a metal block, welded with two horizontal plates. The welded<br />
joint of the head assembly was first sectioned at an appropriate location, as shown in Figure 5-<br />
3(a). Grinding, polishing and etching were carried out as shown in Figure 5-3(b), so as to reveal<br />
the microstructure. Figures 5-4(a) and 5-4(b) show typical microstructures at welded joints.<br />
They both show good weld interfaces between weld metal and metal block or plate.<br />
(a) slice on the LHS for examination<br />
(b) polished and etched surface<br />
Figure 5-3 : Cross-section sample for examination of welded joints<br />
(a) bottom LH weld<br />
(b) top RH weld<br />
Figure 5-4 : SEM micrographs of welded joints<br />
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