DPO Quality Control & Inspection 3 — Questions and Answers
Question 1: During an FMEA verification test, a single failure causes the DP system to lose all position reference inputs. This outcome indicates:
- The FMEA was correctly executed and the failure is acceptable
- A common cause failure exists that the FMEA failed to identify or mitigate (Correct answer)
- The test was conducted outside the approved trial procedure
- The vessel's DP class notation should be downgraded
Correct answer: A common cause failure exists that the FMEA failed to identify or mitigate
Losing all reference inputs from a single failure reveals a common cause vulnerability that should have been identified and eliminated during FMEA design.
Question 2: Which quality standard is specifically referenced for the competency assessment and certification of DP operators conducting inspections on DP equipment?
- ISO 9001:2015
- IMCA C 002 (The Competence Assurance and Assessment Standard) (Correct answer)
- STCW Manila Amendment requirements
- Class society DP notation requirements
Correct answer: IMCA C 002 (The Competence Assurance and Assessment Standard)
IMCA C 002 provides the industry standard framework for competence assurance and assessment of DP operators.
Question 3: An inspection finds that the DP system's consequence analysis software has not been updated to reflect a recent thruster modification. The MOST significant risk this creates is:
- Non-compliance with class survey requirements
- Incorrect worst-case failure predictions that could lead to operating in conditions beyond actual capability (Correct answer)
- Loss of DP class notation at next survey
- Increased fuel consumption during operations
Correct answer: Incorrect worst-case failure predictions that could lead to operating in conditions beyond actual capability
Outdated consequence analysis software can give operators false confidence by predicting capability that no longer reflects the vessel's actual configuration.
Question 4: During inspection of DP position quality, the DP operator notices one DGPS reference shows a standard deviation three times higher than the other two DGPS units. The correct quality control action is to:
- Accept all three inputs as the DP computer will weight them appropriately
- Immediately inhibit the suspect DGPS and investigate the cause (Correct answer)
- Reduce the position acceptance radius for that reference
- Notify the bridge watch officer and continue operations
Correct answer: Immediately inhibit the suspect DGPS and investigate the cause
A reference with significantly elevated standard deviation is unreliable and should be inhibited to prevent it from degrading DP position quality.
Question 5: A quality control inspection of change management records reveals a software patch was applied to the DP controller without a formal Management of Change (MOC) process. The PRIMARY concern is:
- The software patch may have voided the warranty
- Undocumented changes could introduce unknown failure modes not covered by the FMEA (Correct answer)
- The class society was not notified within the required timeframe
- Crew training records may not reflect the change
Correct answer: Undocumented changes could introduce unknown failure modes not covered by the FMEA
Bypassing the MOC process means the patch's effect on the FMEA-validated failure modes is unknown, potentially creating new single-point failures.
Question 6: When conducting a quality inspection of wind sensor data on a DP vessel, which error would most adversely affect DP performance in dynamic conditions?
- A fixed offset of 5° in wind direction measurement
- A delay of 15 seconds in wind speed update rate to the DP controller (Correct answer)
- Wind sensors mounted in a non-obstructed location
- Minor calibration drift of 2 knots in wind speed measurement
Correct answer: A delay of 15 seconds in wind speed update rate to the DP controller
A 15-second update delay means the DP feed-forward wind model is reacting to old conditions, reducing its effectiveness during rapidly changing wind.
Question 7: During an audit, a DPO discovers that consequence analysis was performed using 'worst-case' sea state, but actual operations regularly occur in more severe conditions. This quality gap means:
- Operations have been conducted safely and no action is required
- The vessel has been operating without knowing its true DP capability limits in those conditions (Correct answer)
- The consequence analysis must be repeated daily
- Class society approval is required before any further operations
Correct answer: The vessel has been operating without knowing its true DP capability limits in those conditions
Operating beyond the sea state used for consequence analysis means the actual worst-case failure scenario is unknown, creating an unquantified safety risk.
DPO Quality Control & Inspection 3
During an FMEA verification test, a single failure causes the DP system to lose all position reference inputs.
This outcome indicates: