Selected by Westland

Citation

(1998), "Selected by Westland", Anti-Corrosion Methods and Materials, Vol. 45 No. 1. https://doi.org/10.1108/acmm.1998.12845aab.001

Selected by Westland

Methods

Selected by Westland

It is reported that GKN Westland have chosen the Sifco Selective Plating Process and specified it as a technique to provide fast effective protection from wear and corrosion for specific applications on both Lynx and Sea King helicopters. Six Sifco work stations have seen purchased and training provided to more than 30 technicians in the use of the Sifco Process. This will ensure a quick and effective response to specific work requirements and can be implemented from many locations worldwide.

All airframes require protection from the elements and the resulting corrosion. When metals are exposed through wear or machining a new protective film must be re-instated as soon as possible.

With many Lynx and Sea King helicopters operating with naval forces the salt laden atmosphere accelerates corrosion of any exposed metal surfaces especially in the high humidity of tropical and sub-tropical regions.

Components such as the Lynx's tail cone forks, pylon lugs and their bushes are typical of the parts that require the application of the Sifco Process, whether they are being repaired or replaced. These components provide the hinge assembly for the tail section. As a result of vibration in operation the original cadmium plating is removed and the bushes worn, exposing bare metal to the risk of corrosion.

The GKN Westland approved Sifco Selective Plating Process being applied to the tail rotor section of a Lynx helicopter

The Sifco Process will apply Sifco's own Cadmium LHE solution to provide a speedy and easily executed remedy, rebuilding the original bush bores and end faces to as new tolerances and surface specification. Alternatively if new bushes are required the bores will be machined to an over size tolerance to allow for in situ plating, rebuilding the bores to exact dimensional requirements whilst providing high wear resistance and corrosion protection.

As a result of the success of using the Sifco Process on the Lynx. Westland have also specified the process for Sea King helicopters in similar applications involving airframe lug bores and spot faces. However, selective sulphuric anodising is necessary in these applications to provide the corrosion protection to the selected areas.

In addition to proving the process, supplying equipment and training, it was necessary for Sifco to develop special tooling to enable the process to be applied in situ to the specific surfaces and maintain a high level of operational hygiene.

Using the special anodes and sealing, flow through solution delivery is used to optimise the operation whilst ensuring the solutions are effectively contained within the work area on the Lynx. However, anodising using the Sifco Process required on Sea King uses solutions in a gel form and therefore is easily controlled with no spillage or wastage.

The Sifco process of selective plating is a specialist system developed specifically to provide the localised deposition of a wide range of metals onto metal from solution for a wide variety of reasons.

We are informed that GKN Westland has now written the Sifco Process into their procedures as the provider of equipment, accessories and solutions.

Sifco is a leader in the development of the selective plating process and equipment which is approved and specified by most of the worlds civil and military aircraft manufacturers and operators.

Briefly, the Sifco Process deposits metal on metal from solution by passing a DC electric current from the postive terminal of the power pack through an anode which also applies the metal solution, to the workpiece. The workpiece is connected to the negative terminal to become the cathode. Maintaining relative movement between the anode and the area being treated, metal is deposited with a full molecular bond to the base metal. To create an anodic film the tools and equipment remain the same only the electric current is reversed.

Details are available from Sifco Selective Plating Ltd, 38 Walkers Road, Moons Moat North, Redditch, B98 9HD. Tel: 01527 68008.