AK20I means 80% nitric acid + 20% N2O4 + Iodine passivant
AK = Azotna Kislota = Nitric Acid in
NASA
Similar to AK20I
AC - Alternating Current
AC - Assembly Complete
ACBM - Active Common Berthing Mechanism
ACC - Aft Cargo Carrier
ACCA - Automatic Cloud Cover Assessment
ACCMS - Advanced Checkout, Control, and Maintenance System
ACCS - Advanced Checkout and Control System
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