Globally, an average of 150,000 planes take off and land at around 50,000 airports each day. With aircraft observing thousands of “cycles” (takeoff and landing) a year, rigorous periodic inspections are paramount. Every time an aircraft is pressurized, its wings and fuselage are stressed. The rivets, fasteners, and plates that make the airplane fatigue over time, given birth to incipient cracks around the fastener holes that might lead to bigger cracks and serious safety issues if not attended.
To ensure the aircraft’s reliability, non-destructive inspections are undertaken both during production and throughout the airplane’s lifespan. During maintenance and servicing, various parts of the plane are meticulously examined using a vast array of technics, spanning from visual (VT) to ultrasound (UT) to radiographic testing (RT). The most accurate methods can detect cracks and default as small as 0.04 inch.
In industrial radiography, silver films have been the norm for close to a century. However, in recent years, innovative companies such as Teledyne DALSA and Teledyne ICM have been introducing new digital systems that are revolutionizing the industry. The aerospace world is no exception as we see an increasing number of commercial airlines and military bodies embracing digital radiography (DR).
These organizations operate the switch from films to digital radiography based on factors such as exposure time, image quality, ease of use and costs.
Time component has always been a crucial factor in the aerospace industry. With GO-SCAN, the 49µ – 4×6 inch portable digital system developed jointly by Teledyne DALSA and Teledyne ICM, the exposure time required to get an image of a 20 mm aluminum plate with a constant potential generator such as the CP160B (Teledyne ICM), is less than a second, while it can take up to a minute with regular silver films. The digital process also bypasses the time it takes the operator to retrieve, treat, develop and finally interpret the film. This new technology does not only speed-up the exposure time but the entire radiographic operation as well.
When it comes to image quality, Digital Detectors Arrays (DDAs) are reaching new heights. With modes of digital radiographic image quality metrics such as the Contrast-to-Noise Ratio (CNR) and Signal-to-Noise Ratio (SNR) entering the industry, the quality of images obtained with digital systems are unmistakably becoming the new benchmark. In order to obtain an image quality matching specific American and International standards (ASTM – ISO), the Go-Scan system, for instance, takes and averages as many pictures as needed to match CNR and SNR levels dictated by those standards.
Radiographers around the world, and particularly in the aerospace industry, are well aware of the costs linked to disposables such as films and chemicals. Even though the initial investment might represent a barrier to the acquisition of such equipment, the ROI observed over a few months in terms of operating time, disposables costs, and storage is manifest.
While DR might seem a daunting technology at first, it becomes quickly clear to the operator that the learning curve is anything but steep. With user-friendly software like the one implemented in the Go-Scan, radiologists are able to interpret, analyze, and edit images directly next to the aircraft without having to go back to a lab for development and analysis.
With those image-editing software platforms, aerospace technicians are now able to easily detect defects such as porosity, water entrapment, crushed core, cracks, corrosion, inclusions and loose fittings in a matter of seconds and quickly archive and store those images and analyses in the system.
As the commercial and military aerospace industry is moving forward and adopting new technologies to better their performance, the manufacturers of Non-Destructive Evaluation solutions have to adapt to this rapidly changing industry and offer solutions tailored to those increasing needs and requirements.
Laurent Colson.
Marketing & Communication Manager at Teledyne ICM.