TC reported loud bang sound at TDM +8. SM (AMK) took cab ride on T220 and confirmed no abnormalities . ~~~~~ Checked #3565 vertical dampers and torsion arms ok. Checked and found #3565 bogie 1 lateral damper oil leaking. Not: 2227581 raised to RSW for #3565 bogie 1 lateral damper c/o. Downloaded ER on PTU006. No fault code observed on Tims. Observed impact marking on #3565 end mask. Checked by Joshua. 09/12/20.