Which operating mode does not have separate hydraulic lines for the T-54A?

The operating mode that does not have separate hydraulic lines for the T-54A is the manual retraction mode. This mode relies on a simpler mechanical system rather than an independent hydraulic system. In contrast, other modes such as gear extension, flap operation, and brake system utilize dedicated hydraulic lines due to the complexity and precision required for their operation.

In manual retraction, the emphasis is on direct mechanical operation, which simplifies the system and reduces potential points of failure associated with complex hydraulic lines. Therefore, understanding that manual retraction bypasses the need for separate hydraulic lines helps clarify the operating dynamics of the T-54A system.