FFP55375_01011990 FFP50508_01011900 FFP50512_01011900 FFP52744_01071999 FFP50510_01011900 FFP52724_01071999 FFP55355_01011990 FFP55058_01011990 FFP60833_01012000 FFP60793_01012004 FFP60963_01012000 FFP60964_01012000 FFP60606_01011990 FFP60607_01011990
A quick search on My Oracle support revealed some articles with similar errors for 11i:
Applied Patch 9062727 (11i.Hr_pf.K.Delta.5) And Left With FFP<######> Invalid Packages [ID 1096417.1]
The above article pointed to this article:
How to compile fast formula from the server (via FFXBCP) (Doc ID 167689.1) and I executed this command:
$ FFXBCP apps/apps 0 Y %% %%
Log filename : L5826316.log
Report filename : O5826316.out
All the FFP invalids were resolved after executing the above command.