Over several years, our engineers have inspected the same Local Exhaust Ventilation (LEV) system at an aerospace component facility. Despite repeated failures and serious control issues, the system had continued in use — routinely marked as “satisfactory” by an external insurance assessor.
The LEV in question was originally installed for the cleaning and refurbishment of aircraft brake assemblies — a process that historically involved asbestos-based friction materials.
System Description
The system consists of a small partial enclosure connected to a larger duct system that has been adapted and modified multiple times over the years.
One branch of the ductwork included a 100 mm flexible hose, which had been bagged off after becoming redundant. The partial enclosure itself exhibited negligible face velocities and failed basic smoke control tests, showing almost no capacity to capture or contain contaminants.
Observations
The face velocities were effectively zero, indicating total loss of containment.
A smoke test confirmed that airflow was not directed into the enclosure — instead, the contaminant spread freely into the operator’s breathing zone.
The ductwork alterations had never been re-balanced or re-commissioned.
The fan discharge terminated directly over a car park, creating the potential for re-entrainment and wider environmental exposure.
Given the system’s historical purpose (cleaning asbestos-containing brake dust), there is a realistic risk that asbestos particulate may have been discharged through this point in earlier years.
Root Cause
The ongoing issue stems from a lack of technical competency in previous testing and assessment.
The insurance assessor, while fulfilling a basic inspection role, had repeatedly passed the system as "good" — treating it as simply a duct and a fan, without understanding the airflow dynamics, capture velocities, or historical process hazards that underpin LEV performance.
This approach highlights a wider problem within the industry: LEV systems are too often judged visually, not functionally.
Outcome
Upon our full inspection and quantitative testing, the system was formally failed under COSHH Regulation 9 for inadequate control.
The company has now been advised to:
Decommission and isolate the system immediately.
Review the historical use of the LEV to assess any potential asbestos contamination.
Engage a competent LEV designer and tester for a full redesign and safe replacement.
Key Takeaway
This case underlines the critical need for competency in LEV testing and management.
Testing an LEV isn’t about ticking boxes or confirming that air is “moving.” It’s about understanding why that air is moving, what it’s controlling, and where it’s going.
When hazardous processes — particularly those with a history of asbestos exposure — are involved, that understanding becomes a legal and moral responsibility.