FAA Powerplant Written Practice Test

What method is used to inspect a steel propeller hub for cracks?

1. Ultrasonic inspection

2. Magnetic particle inspection

3. X-ray inspection

4. Visual inspection

The correct answer is: Magnetic particle inspection

The recommended method for inspecting a steel propeller hub for cracks is magnetic particle inspection. This technique is particularly effective for detecting surface and near-surface discontinuities, such as cracks, in ferromagnetic materials like steel. During the process, a magnetic field is applied to the part being inspected. If there are any cracks or other defects, they will interrupt the magnetic field, resulting in the creation of magnetic particles that gather at the site of the discontinuity. This accumulation can then be visually analyzed to identify and determine the location and size of any cracks present. This method is preferred in aviation maintenance because it can quickly and accurately identify flaws that may affect the integrity and safety of the propeller. Other methods, such as ultrasonic and X-ray inspections, are also used in various scenarios but are generally more complex and less suitable for this specific application compared to magnetic particle inspection. Visual inspection, while useful, may not reliably detect all cracks, especially those that are not immediately visible on the surface.