ACS Non-Destructive Testing (NDT) Methods 3

Question 1

What type of radiation is used in radiographic inspection of aircraft structural components?

Accepted Answer

X-rays or gamma rays

Answer

Radiographic inspection uses X-rays (from an X-ray tube) or gamma rays (from radioactive isotopes such as Iridium-192) to penetrate materials and expose a detector or film.

Question 2

On a radiographic film, a darker area (higher film density) typically indicates what about the inspected material?

Accepted Answer

A void, crack, or area of reduced material density allowing more radiation to pass through

Answer

Darker areas on radiographic film indicate that more radiation reached the film in those regions, which occurs where material density is lower — such as at voids, cracks, or inclusions of lower-density material.

Question 3

What is the purpose of a penetrameter (Image Quality Indicator, IQI) in radiographic testing?

Accepted Answer

To verify that the radiograph has sufficient sensitivity and quality to detect a defined minimum flaw size

Answer

An IQI/penetrameter is placed on the part during exposure; its visibility on the finished radiograph confirms that the technique has adequate sensitivity to detect the minimum required discontinuity size.

Question 4

Which NDT method is most appropriate for detecting delaminations in a carbon fiber reinforced polymer (CFRP) aircraft panel?

Accepted Answer

Ultrasonic testing (pulse-echo or through-transmission)

Answer

Ultrasonic testing is the preferred method for detecting delaminations in CFRP composites because delaminations create internal interfaces that reflect ultrasonic energy, and the method works on non-conductive materials.

Question 5

What is the primary radiation safety concern for technicians performing X-ray radiographic inspection?

Accepted Answer

Cumulative exposure to ionizing radiation increasing the risk of biological harm

Answer

Ionizing radiation (X-rays and gamma rays) can damage living tissue and DNA; cumulative occupational exposure is regulated by the NRC/OSHA, and technicians must use dosimetry badges and stay within annual dose limits.

(ACS) Airman Certification Standard Certified Mechanic Practice Test

(ACS) Airman Certification Standard Certified Mechanic Practice Test

ACS Non-Destructive Testing (NDT) Methods 3