Non Destructive Testing

At Deltair, we have a dedicated N.D.T. department specialising in Magnetic Particle Inspection (MT), Fluorescent Penetrant Inspection (PT) and Eddy Current Inspection (ET). We hold full D1 approval for ALL aircraft components that require NDT. We currently carry out NDT inspections on new manufactured components for several of the worlds largest Aerospace manufacturing companies.

Magnetic Particle Testing

Magnetic particle inspection (MPI) is a non-destructive testing (NDT) process for detecting surface and subsurface discontinuities in ferrous materials. The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. Direct magnetization occurs when the electrical current is passed through the test object and a magnetic field is formed in the material. Indirect magnetization occurs when no electrical current is passed through the test object, but a magnetic field is applied from an outside source. The magnetic lines of force are perpendicular to the direction of the electrical current which may be either alternating current (AC) or some form of direct current (DC) (rectified AC).

The presence of a surface or subsurface discontinuity in the material allows the magnetic flux to leak. Ferrous iron particles are applied to the part. The particles may be dry or in a wet suspension. If an area of flux leakage is present the particles will be attracted to this area. The particles will build up at the area of leakage and form what is known as an indication. The indication can then be evaluated to determine what it is, what may have caused it, and what action should be taken if any.

Eddy Current Procedures

During the overhaul of Hartzell type propellers, a procedure of NDT
(non-destructive testing) is carried out using specialist equipment. Deltair to date have used a sub-contractor company for this procedure which with the added burden of freight is expensive and time consuming.

Deltair recently purchased the new piece of equipment to enable the eddy current procedure to be carried out in-house during the overhaul of Hartzell type propeller blades.

In addition to the equipment, the qualification of the personnel is very important and it is mandatory that Deltair work to the letter of their approvals. Level 2 qualification is required by our Inspection operatives to carry out this inspection work.

The result of this specialist training will be a lowering of costs for each Hartzell type propeller overhaul. Deltair are also looking at the possibility of using these unique skills to carry out the procedure for other propeller overhaul shops.

Flourescent Penetrant Inspection

In Fluorescent Penetrant Inspection (FPI) or Liquid Penetrant Inspection (LPI) the surface of a part is saturated with a dye. The dye is cleaned off and a developer is applied to the part, drawing out any dye that has penetrated imperfections such as cracks, to reveal surface irregularities. Our skilled inspection technicians use ultraviolet and white-light inspection booths to examine and record these defects.

Fluorescent Penetrant Inspection or Liquid Penetrant Inspection is most often used with non-magnetic metals including titanium, magnesium and aluminium; however it can be applied to ferrous alloys if desired