This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

ATA/CPD Carnets Manual

Goods for which the EU will accept third country ATA carnets: spare parts and accessories

Goods Spare parts, accessories and equipment used for repair and maintenance, including overhaul and adjustment, of ATA carnet goods.
Conditions of use The goods being repaired, overhauled, and so on must be re-exported from the EU together with the temporarily imported parts.
Legislation Istanbul Convention ****; Commission Regulation 2454/93 Article 577