Alternating Current Field Measurement Testing for the inspection and monitoring of in-service Armoured Vehicles
Alternating Current Field Measurement project results in 168 man hour reduction per vehicle which incorporates a fleet of 27 vehicles. This equates to a total saving of 4,536 hours across the contract and provides access to permanent inspection data files for the fleet of vehicle models.
Tru-Tec NDT led the proposed inspection regime for the in-service assessment for a fleet of Armoured Vehicles operated and serviced by the Ministry of Defence.
The vehicles requiring inspection undergo prolonged and exceptionally demanding training simulations at the British Army Training Unit Suffield (BATUS) based in Canada.
BATUS is the United Kingdom’s live training simulations/exercises where the vehicles are subjected to live firing and movement stresses for periods of over six months which is conducted in demanding temperatures and ground conditions. This is implemented to train staff to maintain, repair and use the specified equipment.
At the end of the BATUS Training regime the vehicles are returned to the Ministry of Defence for repairs and in-house inspection services before being re-released for further simulations.
Previously the non-destructive testing surface methods utilised included Liquid Penetrant Testing (PT) and Magnetic Particle Testing (MT). These methods required the full removal of military grade coating which encapsulated the examination areas resulting in additional coating removal processes, and re-application which incurred costly and time-consuming procedures totaling 168 man hours per military vehicles.
The project team approached the private industry to find companies competent in new advanced technologies to reduce costs and time. Tru-Tec NDT certified and competent in advanced NDT methods proposed Alternating Current Field Measurement (ACFM) as the chosen surface inspection method.
The benefits of ACFM include the ability to size the length and depth of surface breaking discontinuities, minimal surface preparations are required and can be applied over coatings to establish surface breaking discontinuities thus reducing the downtime associated with coating removal and reapplication.
Armoured vehicles which are fabricated from wrought material and cast material can demonstrate spurious indications when utilising conventional Eddy Current Testing (ET), however due to the innovative system and probe updates within the ACFM unit, the lift off effect is minimalised when carrying out inspections, resulting in a smoother scan pattern with minimal spurious indications resulting in the reduction of false calls.
ACFM equipment records, stores the inspection data, and scan plan which is beneficial for creating an initial inspection footprint. This footprint can be recalled for assessment with subsequent inspections and to reciprocate the inspection regime whilst on training and live firing situations. This is a useful tool to monitor discontinuities that have been detected but not repaired, allowing the vehicle to be put back into service and defect propagation to be assessed and monitored.