Practice Question

1.Suggest why ultrasound might be useful to an aircraft maintenance company.

The ultrasound waves can be used to detect cracks in the structure of metal aircraft. 

2. Ultrasound waves have been used to detect cracks in a metal structure. The oscilloscope screen has 5 peaks in it. Calculate how many cracks are present in the metal structure

5-2 = 3

Two of the peaks are due to transmission and end of the metal. So, there are 3 cracks in metal structure.

3. Explain how ultrasound is used to detect cracks in a metal structure.

Ultrasound wave passes through metal structure, part of the wave is reflected back at the boundary of crack. This causes a peak on the oscilloscope, which can then be seen.

4. Ultrasound waves travel through metal X at a speed of 7000m/s. The time scale on the oscilloscope is set to 0.00010 seconds per box. There is a difference of 4 boxes between the transmitted peak and the peak due to a crack. Calculate the depth of the crack.

Distance(depth) = speed x time

Time = 0.0001 x 4 boxes = 0.0004 seconds

Distance = 7000 x 0.0004 = 2.8m