I bought recently from a family this helmet but I can't recognize the insigna. This helmet belonged to a French soldier having a Captain rank:
In 1948, Captain 6° Bataillon de Tirailleurs Sénégalais,
In 1950-1951 Captain du Bataillon colonial de Saigon Cholon and
In 1951, Captain 31° Bataillon de Marche de Tirailleurs Sénégalais.
A friend of mine told me that the insigna colors could match with the 3rd South Vietnamese recognition squadron. To my opinion, this soldier may have taken part in the 2 WW and then been sent to Indochina.
Best regards. Georges.