Flt Lt Montree Jumrieng, Thai Airways International's vice-president of the technical department, said the department plans to change from being a cost-centred unit to a profit-centred unit.
It plans to increase outside customers to 50% of total services.
The department currently provides most of its services to THAI carriers.
The technical department expects it can generate anual income of up to 50 billion baht by 2020, up from the current 9 billion baht.
Of the current total, 8 billion comes from THAI.
Flt Lt Montree said the department plans to transform the THAI unit in 2015 with an investment of 10 billion baht and expand its business to include more outside customers, including hangar expansions at Suvarnabhumi airport.
The business expansion plan is in line with the expansion of low-cost airlines and carriers' maintenance needs and repair services in the region.