The investigation of fin plate of MiG-29 aircraft made of aluminium alloy D19 using conventional ultrasonic testing (A-Scan System) / Siti Nur Hasanah Hamzah.

The attachment of the fin plate of MiG-29 aircraft was inspected by using conventional ultrasonic testing method. Ultrasonic non-destructive testing, also known as ultrasonic NDT or simply UT, is a method of characterizing the thickness or internal structure of a test piece through the use of high frequency sound waves. The frequencies, or pitch, used for ultrasonic testing are many times higher than the limit of human hearing, most commonly in the range from 500 KHz to 20 MHz. Ultrasonic testing was significant for quality assessment and evaluation of the critical part component in aircraft such as the fins without altering or damaging the material under the test. Pulse echo technique is the most common technique used in ultrasonic testing which make used the phenomenon that sound waves travel in straight line and are reflected by an obstacles placed in their way. The effects of different probes frequency (5MHz, 10 MHz and 20MHz) were observed by analyzing the signal produced from the ultrasonic test set being used. Higher frequency probes have shorter wavelength and this will increase the sensitivity to locate the defect in the test material. Therefore, for a thin material as the fin plate it was recommended to use a higher frequency since it promotes a shorter wavelength into the test material being inspected. Since the type of material and couplant used have severe affects on the testing results, therefore the material and the type of couplant used were kept constant throughout the inspection. Throughout the testing, fin plate made of aluminium alloy D19 and couplant (petroleum grease) were used to ensure the different variables affecting the result of the testing.