Difference Between Audit and Survey

1. What Is a Survey?

• A survey focuses on future activity so that the equipment continues to work until the next survey.
• It focuses on the physical status of the machinery.
• It focuses on hardware.
• A survey of the entire system is possible — equipment survey, main engine performance survey, boiler survey, etc.
• Example: in a survey of a fire pump, the surveyor will check the satisfactory repair of the pump and that the noted deficiency has been removed.

Who Carries Out Surveys:

• Classification society surveyors — for class surveys (hull, machinery, boilers, tailshaft, etc.).
• Administration / Flag State or recognised organisation — for statutory surveys and certificates.
• Port State Control officers — for port State inspections on operational requirements.

2. What Is an Audit?

• An audit forecasts the past activity, then detects the fault and ensures proper corrective action.
• It focuses on system operation, procedures, documentation and software.
• It always looks at the system.
• Example: an auditor will check the satisfactory repair of a pump and will enquire, find and analyse when the pump was last inspected and why the deficiency was not found before the survey.

Who Carries Out Audits:

• ISM auditors (internal and external) — for the Safety Management System.
• The company / DPA — internal audits and management reviews.
• Flag State / recognised organisation — DOC and SMC verification (ISM).

The key question. The defining question of an audit is: "Why was the fault not found before?" An audit does not stop at the physical defect — it traces back through the planned maintenance, procedures and records to find the management-system reason the defect was missed.

3. Key Differences

One-line answer. Survey = hardware (physical condition of machinery for future operation); Audit = software/system (procedures, documentation and records, looking back to find why a fault occurred and ensure corrective action).

4. Examples & How They Work Together

Worked Example — A Fire Pump:

• Survey: the surveyor attends the fire pump, checks that the repair is satisfactory and that the deficiency noted earlier has been removed.
• Audit: the auditor also sees that the pump is now repaired, but then enquires when the pump was last inspected and why the deficiency was not found before the survey.
• The audit therefore examines the planned maintenance system, records, procedures and responsibilities that should have detected the defect.

How They Complement Each Other:

• The survey finds the physical defect and verifies the repair.
• The audit finds the systemic reason the defect existed or was missed and drives corrective and preventive action.
• Together they keep the ship safe: the survey keeps the hardware working, the audit keeps the management system working.

Surveyor asks: "What is the difference between an audit and a survey?" Answer: Survey = physical/hardware + future activity; Audit = system/procedures/documentation + past activity. Give the fire-pump example to make it clear.

5. Chief Engineer Survey of Machinery Items & Scope (CMS Scheme)

Continuous Machinery Survey (CMS) & Chief Engineer Authorization:

Under the Continuous Machinery Survey (CMS) system operated by major Classification Societies (such as Lloyd's Register, DNV, ABS, ClassNK), the 5-year special survey cycle for machinery is divided into manageable increments. Approximately 20% of all machinery items are surveyed each year so that all machinery items are thoroughly examined within the 5-year cycle.

To provide operational flexibility during voyages, Classification Societies permit a qualified Chief Engineer (holding a valid Class 1 / Chief Engineer Unlimited Certificate of Competency) to survey designated machinery items during regular overhauls at sea or in non-surveyor ports, subject to formal Society approval.

Work carried out under Chief Engineer authorization remains confirmatory: the attending Class Surveyor still performs a visual audit of the item at the next port where a surveyor attends.

The machinery items a Chief Engineer may survey cover four groups:

Auxiliary Diesel Engines

Complete overhaul inspection of cylinder heads, inlet/exhaust valves, fuel injectors, pistons, piston rings, cylinder liners (wear calibration), gudgeon pins, top-end and bottom-end bearings (clearance calibration via lead wire or plastic gauge), and camshaft driving gear.

Auxiliary Pumps & Motors

Centrifugal and positive displacement auxiliary pumps: seawater circulating pumps, fresh water cooling pumps, bilge pumps, general service pumps, ballast pumps, fire pumps, lube oil pumps, and fuel oil transfer pumps (impellers, casings, shafts, wear rings, and bearings).

Starting Air Compressors

Main and auxiliary air compressors: low-pressure and high-pressure pistons, piston rings, cylinder walls, suction and delivery valve assemblies, intercoolers, aftercoolers, and crankcase running gear.

Heat Exchangers & Auxiliary Systems

Plate and shell-and-tube heat exchangers: main engine lube oil coolers, jacket water coolers, central coolers, steam condensers, and fuel oil heaters (cleaned, tube plates inspected, pressure tested for leakage).

Warning — Items Explicitly EXCLUDED from Chief Engineer Survey

These items must be surveyed by the attending Class Surveyor only, never by the Chief Engineer:

• Main Engine Running Gear: Main engine crankshaft, bedplate, main bearings, thrust bearing, and crosshead bearings (unless specially authorized under an approved Condition Based Maintenance / CBM scheme).
• Boilers & Steam Plant: Internal water-steam spaces and safety valve setting of main, auxiliary, and exhaust gas economisers.
• Steering Gear: Hydraulic actuators, hunting gear, telemotor controls, and emergency tiller arrangements.
• Tailshaft & Propeller: Stern tube bearings, seals, and propeller fastening.
• Ship's Bottom Openings: Sea inlet chests, ship-side overboard valves, and distance pieces.
• Electrical Switchboard Protections: Generator preferential trips, reverse power relays, and air circuit breakers.

Mandatory Chief Engineer Documentation & Verification Protocol:

1. Pre-Planning: Verify the component is due or eligible for CMS survey in the Class Survey Status report and Planned Maintenance System (PMS).
2. Dimensional Calibrations: Meticulously measure and record all critical engineering dimensions: micrometer readings of liner bore diameter at top, middle, and bottom (transverse and longitudinal); micrometer readings of piston skirt and ring groove clearances; feeler gauge or lead-wire clearances of connecting rod bearings; and crankshaft web deflections.
3. Photographic Evidence: High-resolution photographs with date/time stamps showing: the component in opened condition, parts cleaned for inspection, etched part/serial numbers, micrometer/feeler gauges taking readings, and new replacement parts installed.
4. Retention of Replaced Components: Worn or replaced components (e.g. scored bearing shells, worn piston rings, damaged valve spindles) must be cleaned, tagged, and retained in the engine room for physical examination by the attending Class Surveyor at the next port.
5. Formal CMS Log & Endorsement: The Chief Engineer enters detailed findings and measurements into the official Classification Society CMS Report and vessel PMS. When the ship reaches a port where an exclusive Class Surveyor attends, the surveyor audits the documentation, inspects the retained parts, witnesses running tests, and officially credits the survey item in the society's register.