Abstract: The invention relates to a contamination recording apparatus (12) for recording contaminations in a flowing hydraulic fluid (10) to be examined in aircraft (11a), which comprises a conveying device (14) for conveying the flowing hydraulic fluid (10), a light source (34) for exposing the hydraulic fluid (10) flowing in the conveying device (14) to light (46), and a detection device (36) for recording a fraction of the light (46) absorbed by the exposed hydraulic fluid (10), the light source (34) being formed in order to emit light (46) having a wavelength in the near-infrared range. The invention furthermore relates to a hydraulic system (11) equipped with such a contamination recording apparatus (12) and to an aircraft (11a), and also to a method for recording contaminations in a hydraulic fluid (10) flowing in a hydraulic system (11) of an aircraft (11a).