DPO Quality Control & Inspection 2 — Questions and Answers
Question 1: During a DP Annual Trial, which document must be referenced to confirm all tests are conducted as originally approved?
- Vessel's Safety Management System manual
- FMEA proving trial procedure approved by the class society (Correct answer)
- IMO MSC Circular 645 checklist
- Manufacturer's commissioning report
Correct answer: FMEA proving trial procedure approved by the class society
Annual DP trials must follow the FMEA proving trial procedure approved by the class society to ensure consistency and validity.
Question 2: A reference system is found to have a consistent 2-meter offset during position quality inspection. The FIRST corrective action should be to:
- Switch to an alternative reference system immediately
- Check and update the antenna offset values in the DP system configuration (Correct answer)
- Increase the position acceptance radius in DP settings
- Log the discrepancy and continue operations
Correct answer: Check and update the antenna offset values in the DP system configuration
A consistent positional offset typically indicates incorrect antenna offset or lever-arm values entered in the DP configuration.
Question 3: When inspecting DP thruster feedback signals, which condition would indicate a quality control failure requiring immediate investigation?
- Thrust demand lagging thrust feedback by 1–2 seconds
- RPM feedback indicating 5% below demanded RPM under load
- Pitch feedback reading opposing the demanded direction (Correct answer)
- Minor azimuth deviation of 2° from demanded heading
Correct answer: Pitch feedback reading opposing the demanded direction
Pitch feedback reading in the opposite direction to demand indicates a critical signal inversion fault that could cause uncontrolled thrust.
Question 4: Under IMCA M 166 guidelines, how frequently should a full DP capability plot be verified against actual vessel performance?
- Every voyage
- Every 5 years during dry-dock
- Annually or after significant changes to the vessel's DP equipment or structure (Correct answer)
- Only following an incident report
Correct answer: Annually or after significant changes to the vessel's DP equipment or structure
IMCA M 166 recommends re-verifying DP capability plots annually or whenever major changes affect vessel performance or equipment.
Question 5: During inspection of a DP vessel's UPS (Uninterruptible Power Supply), which test verifies quality of autonomous power bridging for DP continuity?
- Load bank test simulating full thruster demand
- Transfer test timing the switchover from mains to UPS under DP control system load (Correct answer)
- Short-circuit protection relay trip test
- Insulation resistance test of UPS output cables
Correct answer: Transfer test timing the switchover from mains to UPS under DP control system load
The transfer test measures the actual switchover time under DP system load, confirming the UPS provides seamless power bridging without DP controller restart.
Question 6: A quality audit of the DP logbook reveals that consequence analysis was not performed before a critical lift operation. This represents a failure of:
- The maintenance management system
- The pre-operation risk assessment and DP operational planning process (Correct answer)
- Class society survey requirements
- The FMEA documentation update cycle
Correct answer: The pre-operation risk assessment and DP operational planning process
Consequence analysis is a mandatory element of DP operational planning; its omission is a failure of the pre-operation risk assessment process.
Question 7: When inspecting DP gyrocompass quality, what is the primary indicator that a compass is providing unreliable heading data to the DP system?
- Heading drift of more than 0.5° per hour
- Discrepancy of more than 1° between two independent gyrocompasses (Correct answer)
- Gyrocompass precession rate exceeding manufacturer specification
- A difference of more than 2° between gyro heading and GPS COG
Correct answer: Discrepancy of more than 1° between two independent gyrocompasses
A heading discrepancy exceeding 1° between independent gyrocompasses signals a potential fault and requires investigation before DP operations.
DPO Quality Control & Inspection 2
During a DP Annual Trial, which document must be referenced to confirm all tests are conducted as originally approved?