During post-flight checks, evidence of substantial fuel leak was noted from LH engine. Apparent source was at the top of the combustion case including evidence of combustion, external to the engine, forward of the firewall. Further damage on upper engine mount, fuel manifold and adjacent components as well as evidence of high temperatures on engine frames noted. No report of any fire warning, nor any evidence of fuel leak during pre-flight checks. Leak was traced to secondary fuel manifold adjacent to the number 10 fuel nozzle. Investigation continuing. P/No: 31024692.