There are "Nrm" and "Roughmet" files too, so it's necessary to make sure these line are available in the lua file for the chosen F-14 skin.
For the pilot:
{"HB_F14_EXT_PILOT_HELMET", 0 ,"HB_F14_EXT_PILOT_HELMET",false};
{"HB_F14_EXT_PILOT_HELMET", 1 ,"HB_F14_EXT_PILOT_HELMET_Nrm",false};
{"HB_F14_EXT_PILOT_HELMET", ROUGHNESS_METALLIC ,"HB_F14_EXT_PILOT_HELMET_RoughMet",false};
For the RIO:
{"HB_F14_EXT_RIO_HELMET", 0 ,"HB_F14_EXT_PILOT_HELMET",false};
{"HB_F14_EXT_RIO_HELMET", 1 ,"HB_F14_EXT_PILOT_HELMET_Nrm",false};
{"HB_F14_EXT_RIO_HELMET", ROUGHNESS_METALLIC ,"HB_F14_EXT_PILOT_HELMET_RoughMet",false};
Make sure to replace only helmets for skins that you've downloaded in this session for your SAVED GAMES folder. Avoid messing with your root folder.