NZDF Assessment and Repair of ANZAC Frigate Propeller Blades

5 ANZAC Frigate Propeller Blades were sent to Allied Industrial Engineering to be assessed and then repaired. AIE performed specialist 3D scanning on each individual blade. The blades were 3D Scanned and following this the mesh data was overlaid and deviation analysis undertaken to ascertain significant differences in the shape of the blades. The deviation analysis was accurate down to 0.02mm.

Each blade was compared to the others in the set and to the manufacturer’s drawing to ensure they were not bent or warped.

Each blade was individually balanced in a custom designed balancing jig to ensure when the set was bolted to the propeller hub the risk of significant vibration was eliminated. Crack testing was also carried out on the blades at AIE’s premises.

The effectiveness of the Prairie Air Emission Hole System was tested to ensure the holes on the leading edges of the propeller blades were not blocked. These holes help reduce the hydrodynamic noise which originates at the propeller.

It was found that the mating and sealing surfaces of where the blades mount to the propeller hub were not satisfactory. This had the potential to result in oil leakage from the propeller hub. By machining these surfaces to the required specifications, this issue was put to rest.

Once the repair was completed the set of blades was returned to the NZDF Rotable Spares Store.