UV-A in Aerospace Non-Destructive Testing

The aerospace sector operates under some of the most stringent quality assurance requirements of any industry, and non-destructive testing (NDT) is central to maintaining the integrity and airworthiness of components, assemblies and structures throughout their working life. UV-A radiation plays a critical role in two of the most widely used NDT methods in aerospace: Fluorescent Penetrant Inspection (FPI) and Fluorescent Magnetic Particle Inspection (FMPI).

In Fluorescent Penetrant Inspection, components are coated with a fluorescent penetrant fluid that is drawn into surface-breaking defects by capillary action. Following the application of a developer, the component is examined under UV-A radiation (typically at 365 nm) in a darkened inspection booth. Defects are revealed as bright fluorescent indications against the dark background, enabling inspectors to detect cracks, porosity and other surface discontinuities that would be invisible under white light.

Fluorescent Magnetic Particle Inspection follows a similar principle, applying a fluorescent magnetic ink to components under an applied magnetic field. Discontinuities in ferromagnetic materials are revealed as fluorescent particle accumulations under UV-A illumination. Both processes are conducted to strict procedural standards and customer-specific process specifications.

NDT inspectors in aerospace routinely work within UV-A inspection booths for extended periods, often conducting multiple inspection cycles per shift. The UV irradiance levels required by process standards (typically a minimum of 1,000 μW/cm²) at the inspection surface, mean that inspectors can be exposed to significant UV-A levels over the course of a working day, particularly where lamp positioning, working distances and booth design are not optimised from a safety perspective.

Legal Obligations Under the Control of Artificial Optical Radiation at Work Regulations 2010

The CAOR 2010 Regulations place clear and enforceable obligations on aerospace employers and NDT service providers. The fact that a UV-A inspection booth is necessary for the process does not remove the obligation to manage the risks associated with the UV radiation it produces – it simply means that risk must be assessed, quantified, and controlled.

In the context of aerospace NDT, compliance with the Regulations requires:

• A formal risk assessment of UV-A exposure for all personnel who enter or work within inspection booths, including inspectors, technicians and supervisors.
• Measurement of UV irradiance at relevant working positions within the inspection environment, and calculation of personal daily exposure against the statutory ELVs.
• Assessment of existing control measures (including booth design, lamp positioning, PPE and administrative controls) to determine their effectiveness in limiting exposure.
• Provision of information and training to workers, including operators, inspectors and anyone who may be present in a UV-A inspection area.
• Documentation of the assessment process, findings, control recommendations and training records, available for inspection by the HSE or a client’s safety auditors.

In the aerospace sector, where organisations are subject to customer and regulatory audits as well as HSE inspection, the absence of documented UV exposure assessments and worker training is an increasingly identified compliance gap – one that can attract enforcement action and jeopardise the ability to retain customer approvals.

Health Risks from Occupational UV-A Exposure in NDT Environments

The perception that UV-A is inherently safer than UV-B or UV-C is a persistent misconception in NDT environments. While the acute effects of UV-A exposure (such as photokeratitis) are generally less likely to occur than those of shorter wavelengths, the long-term health risks associated with sustained occupational UV-A exposure are significant and deserve serious attention.

• Eye effects — UV-A penetrates more deeply into the eye than UV-B, reaching the lens and potentially the retina. Long-term occupational exposure is associated with an increased risk of cataract formation, and acute high-intensity exposure can cause photokeratitis and photoconjunctivitis.
• Skin effects — repeated UV-A exposure causes cumulative damage to skin at the cellular level, accelerating photo ageing and increasing the long-term risk of skin cancer, including melanoma.

NDT inspectors who spend significant portions of their working day inside UV-A inspection booths may be among the most highly exposed workers in any sector. Without actual measurement of the UV-A levels in their working environment, and without understanding how those levels translate into personal daily exposure, it is simply not possible to determine whether existing controls are adequate or whether individuals are at risk.

How Arden Ultraviolet Can Help

Arden Ultraviolet has extensive experience working with aerospace organisations, including major OEMs, MRO providers and Tier 1 suppliers. We understand the specific demands of NDT environments — the process requirements, the inspection standards, the customer expectations and the health and safety obligations — and we provide practical, independent support to help organisations meet all of them.

Our services for aerospace NDT operations include:

• On-site UV Exposure Assessment — measurement of UV-A irradiance levels within inspection booths and at other relevant working positions, assessment of personal daily exposure for inspectors and other personnel, and comparison against the statutory ELVs, with a written report and compliance statement suitable for audit purposes.
• UV Risk Management Training for safety managers, NDT leads and those responsible for UV processes within your organisation — covering the applicable legislation, the health effects of UV-A radiation, and the principles of effective risk management.
• UV Hazard Awareness Training for NDT inspectors and other personnel who work with or in the vicinity of UV-A inspection equipment.
• UV equipment and PPE assessment – independent evaluation of existing UV lamps, measurement of irradiance output, and verification that protective eyewear provides appropriate attenuation at the specific wavelengths used in your process.

Whether you operate a single FPI line or a large-scale MRO facility with multiple inspection stations, we can provide the evidence-based assessment and training your organisation needs to demonstrate compliance and protect your people.