Rolls-Royce Spey 555-15 is the baseline Spey 500-series turbofan model, distinct from the uprated 555-15H, 555-15N, and 555-15P variants. EASA.E.064 records a two-spool architecture with one five-stage low-pressure compressor and one twelve-stage high-pressure compressor, a 43.81 kN maximum take-off static rating, and a 42.12 kN maximum continuous rating under sea-level ISA test conditions. EASA.A.037 records the exact twin-engine F28 installation for Mark 1000/1000C, 2000, and 3000R/RC aircraft; lifecycle remains unknown because certification and continuing-airworthiness records do not establish current production or universal in-service status.