As you certainly know, normally A/C engineers should wear epaulettes as Pilots And Cabin Crew, Those Epaulettes have Golden Stripes seperated by Brown / Purple Stipes:
1 Stripe- Apprentice
2 Stripes- A+C Mechanic
3 Stripes- Licensed Technician
4 Stripes- Crew Cheif / Station Engineer
you can find somes here