"They're going to repair the engine of the plane."
Translation:Ils vont réparer le moteur de l'avion.
if it is "airplane (or plane) engine (or motor)" i am wondering why there is an article and not just "d'avion. if i am correct that this is a noun modifying (not "possessing") a noun, then usually the article is not included. probably i will be long gone before someone offers an answer.