Lancaster Conservation Progress Report - March, April & May

A diverse range of conservation work has been done on the Lancaster during the last 2 months.

The structural elements of the undercarriage have been dismantled, cleaned and repainted.

G for George undercarriage
Undercarriage Oleopneumatic struts before treatment

Undercarriage Oleopneumatic struts
Undercarriage Oleopneumatic struts after cleaning, treatment and repainting

Work is presently continuing on the wheels. The surface of the tyres is being treated to repair handling damage, and incorrectly applied paint is being removed from the brake hubs and wheels. These will soon be repainted in the correct colours.

All four of the Rolls-Royce Merlins have had their internal coolant passages flushed. Two of the Merlins have now been chemically treated, rinsed and dehumidified1. Soon, a vapourising corrosion inhibitor2 will be added to the water tanks and the radiator/water system will be sealed. Although the engines are largely complete, the work of locating small missing items like sparkplugs and wiring fittings continues.

Rolls-Royce Merlin engine
Rolls-Royce Merlin engine having its coolant system flushed of deposits

Rolls-Royce Merlin engine
Rolls-Royce Merlin engine being dehumidified after flushing to prevent corrosion

The port wing and centre-rear fuselage are currently undergoing treatment. The inboard wing roots4, taboo ring5 and tail-gunner's ammunition tracks, which were damaged in the 50's, have been repaired.
Historical photographs and manufacturers documentation are being used in conjunction with spot rubbing3 to locate the original camouflage and aircraft identification markings. This means that for the first time in 60 years, George can be accurately returned to the paint scheme and markings it had while in active military service.

Spot rubbings on the port wing
Spot rubbings on the port wing to find the original camouflage

Chalkline marking out the position of the 1943 "ARG" markings
Chalkline marking out of the position of 1943 "ARG" markings on starboard side of fuselage

Andrew Pearce
Large Technology Objects Conservator,
Australian War Memorial

Glossary

[1] Dehumidify

Dehumidification means to remove all the moisture from a sealed airspace. In order for corrosion reactions to take place, water is needed. Dehumidifying stops this being able to happen.

[2] Inhibitor

An inhibitor is a chemical compound that prevents corrosion from occurring. A vapourising inhibitor can be enclosed in a sealed space and will flow through the system as a gas and coat the exposed surfaces of the metallic parts.

[3] Spot Rubbing

This is an investigative technique used to locate original markings which have been subsequently covered with newer layers of paint. Fine-grained abrasive paper is used to rub a small hole in the paintwork down to the original metal surface. Every layer of paint appears as a concentric ring of colour on the edge of the spot, with the oldest colours being nearest to the metal.

[4] Wing Root

This is the most inboard section of a wing where it touches the aircraft fuselage. The joint between wing and fuselage is commonly covered with a cloth sealing strip or a metal fairing to smooth the airflow.

[5] Taboo Ring

In the First World War, the guns mounted on aircraft were moved manually. With the advent of hydraulically and electrically powered turrets in the Second World War, it was discovered that a gunner could drive the gun barrels into the side of the fuselage damaging either the aircraft or the guns. The taboo ring fitted to the upper turret of the Lancaster prevents this. As the guns are moved, the small wheels protruding from the turret just below the guns operate a switch when they hit the curved track on the taboo ring. This switch operates the hydraulic system and elevates the guns, thereby ensuring a collision cannot occur.