1. Hydraulic Fluid Loss: The hydraulic system relies on the integrity of its pipelines. Failure can occur due to pipe fatigue from vibrations or from excessive pressure not properly relieved by relief valves. Poor maintenance and corrosion can also weaken pipelines. When a pipeline ruptures, the hydraulic oil is lost, leading to a complete loss of steering power.
2. Pump Failure: The hydraulic pump is the heart of the system. Failure can stem from electrical issues such as a motor's "single phasing," which can burn out the motor, or from problems with cables and contactors. Mechanical failures, such as worn-out bearings, can also cause the pump to seize. In either case, the inability of the pump to move hydraulic fluid results in a loss of steering.
3. Air or Vapor Lock: Unlike a physical component failure, this is a systemic issue. If air or vapor becomes trapped in the hydraulic fluid, it can form an air lock or vapor lock. Because air is compressible, it prevents the hydraulic fluid from transmitting pressure effectively. This leads to sluggish, inaccurate steering or a complete inability to move the rudder to the desired angle, effectively causing a loss of steering control.

• Design: The "single-failure" concept and 100% redundancy are fundamental design principles. This means that if one system fails, a second, equally capable system can take over without any loss of function. Purging points are also strategically placed to remove trapped air or vapor. To prevent the standby pump from "motoring," a block valve or a pawl and ratchet mechanism is fitted. This prevents hydraulic fluid from back-driving the idle pump.
• Operation: During normal operation, crews should regularly check that the pawl and ratchet mechanism is functional and not jammed. In the event of a telemotor feedback failure, the system can often be operated using a non-follow-up steering mode from the wheelhouse, bypassing the faulty feedback loop.
• Maintenance: Regular maintenance is key. This includes the timely overhaul of pumps to check for bearing damage and other issues. The integrity of the electrical systems, including cables and contactors, must be maintained. Regular checks for corrosion on pipelines and structural components are also vital to prevent failures.

An irreparable failure of the steering telemotor, which transmits the steering command from the bridge, can be bypassed to allow the vessel to make port.

Shift control from bridge to local/emergency steering in steering gear compartment.

Disconnect/isolate failed telemotor and operate steering gear by:

• local hand lever,
• non-follow-up push buttons,
• trick wheel (depending on design).

-Establish continuous communication between bridge and steering flat by telephone/radio.

-Bridge gives helm orders; steering flat executes using local rudder angle indicator.

-Reduce speed, avoid congested waters, and use pilot/tug assistance when approaching port.

-If necessary, use engines/thrusters (especially on twin-screw ships) to assist maneuvering.