Bell or airbus helicopter do not make the seats
They are third party components like this one by "zodiac aerospace"
certified:
FAA 14 CFR Part27: Airworthiness Standards. Transport Category Aircraft
EASA CS-27 : Certification Specifications and Acceptable Means of Compliance for Large Rotorcraft
ETSO/TSO-C127a : Technical Standard Order – Rotorcraft, transport airplane, and normal and utility airplane seating system,
ETSO/TSO-C114 : Technical Standard Order – Torso Restraint system
SAE AS8049 : Performance standard for seat in civil rotorcraft, transport aircraft, and general aviation aircraft
SAE AS8043 : Aircraft Torso Restraint system
DO-160G : Environmental Conditions and Test Procedures for Airborne Equipment
As an OEM would make sense not to bother with all that certification process, and buy it all made.