DFT-400

Perform oil sampling analysis every 500 operating hours minimum; check for water content (max 500 ppm per ISO 4406 standard), particle contamination (ISO cleanliness code 15/13/10 minimum), and viscosity at 40°C

Conduct weekly visual inspections of all hydraulic lines, connections, and cylinder seals during operation; check relief valve discharge paths are clear; verify pressure at gauge within ±5% of design specifications per IMO resolution MSC.407(97)

Test rudder movement capability: verify rudder travel from -35° to +35° in less than 28 seconds at maximum loaded draft and service speed (per SOLAS II-1/29); conduct emergency steering drill every 3 months; verify control follow-up systems and non-follow-up lever engagement

Verify pump motor starts without load; test all bridge control positions and autopilot integration before departure (within 12 hours per SOLAS II-1/26); inspect motor cabling for moisture ingress; verify electrical isolation switches and emergency stop functionality

Measure rudder stock bearing clearance annually (tolerance 0.1-0.3 mm per ship class rules); inspect tiller arm bushings for wear; verify all mechanical connections are torqued to specification; ensure unobstructed full rudder travel with no binding or unusual noises