I posted to challenge the statement that corrosion was accelerated by the lake no more no less.

Ross

Well anybody who ever had structural repairs to do on RN aircraft will argue strongly that any water, except distilled, will accelerate corrosion. But then even distilled water once exposed to the atmosphere will take up compounds to make it act as an electrolyte, for that is the basis of the corrosion. This galvanic corrosion happens when dissimilar metals are immersed in an electrolyte. The dissimilar metals can be in different parts of a structure or within an exposed light alloy material. Light alloy, e.g. L72 (an Alclad), contains particles of copper, and other elements, at the grain boundaries which act like keys to lock the molecules of aluminium in the matrix and thus increase the UTS above that of aluminium. Alclad has outer layers of aluminium to inhibit corrosion. The surface of the aluminium exposed to the atmosphere develops an outer layer of oxide which is impermeable to further galvanic action.

Much time, and money, was spent in the prevention and removal of corrosion products on naval aircraft.

Front line, sea going RN heavy jets were assembled with special compounds used at mating faces to inhibit the ingress of moisture. ISTR that the first SHARs assembled had this protection omitted as the RAF did not require it and some rebuilding was required.

Back in late 1972 a GA11, WV381, to which I had fitted a Harley light mod, had a problem on take off from Lee, I was watching it take off having strapped in the pilot, done the necessary and saluted him out onto the peri’ track. The aircraft spent nearly 48 hours in the Solent. The late November weather was foggy, and only the fin tip was just visible above water and took a bit of locating. When lifted out the aircraft was placed in the AAIU (Air Accident Investigation Unit) also at Lee on Solent.

Some time later I had occasion to visit the aircraft, after considerable pressure on the AAIU management, as part of a survey of GA11 rear pressure bulkheads for a proposed new radio fit on the FRADU fleet, we wanted to fix a common position for the connector that was to be fitted in that bulkhead.

The aircraft was on jacks and trestles. As I climbed the ladder and looked into the cockpit I became aware of a loud crackling noise which at first was puzzling. Then it quickly dawned on me that it was the sound of magnesium alloy fittings, e.g., the grip of the control column and instrument panel supporting structures corroding away. The noise was unmissable it was that loud. Undercarriage struts and wheels were also of magnesium alloy.

Helicopters of 1950s and 1960s vintage had trouble obtaining an operational power to weight ratio so so had a more extensive magnesium alloy structure than heavy jets. Thus such aircraft were always more prone to corrosion. Also ISTR that the wing-rib forgings at the wing fold of aircraft such as the Sea Vixen were of magnesium alloy.