Guide vane, brass-coloured · 9 cm

This guide vane stands out: instead of grey it is golden beige, the aerofoil tapers to a wedge, and the head is a transverse T-bar with a bearing eye.

Inside a jet engine's compressor, rotating and stationary blade rows alternate. The stationary ones — the stator vanes — straighten the air for the next stage. Some of them are adjustable: they sit in bearings and are turned together by a ring, so the compressor works as cleanly at idle as it does at full power. That is why this piece has an eye with a bore at its head, where the lever engages, and a spigot on the reverse that runs in the casing.

The golden-beige tone is not paint but sits in the metal — either a temper colour from running hot, or a protective coating of the kind applied to compressor parts. Which of the two cannot be said without testing. What is certain: the tone is even across the whole piece and does not wipe off.

Which engine this came from is not known. There are no papers with it, and apart from its shape nothing identifies the type. The material cannot be named without testing either: compressor blades use titanium, steel or a nickel alloy depending on the stage. What is certain is in the key facts — the rest stays open.

• Length 9 cm
• Golden beige, even, not painted
• T-shaped head with oval bearing eye
• Wedge-shaped, slender aerofoil
• Metal, alloy undetermined
• Loose single piece, no stand

Used, well preserved. The golden-beige surface is continuous, with fine scratches and a few darker patches at the head. Edges undamaged, bearing eye clear, no distortion.