⚠️ Disclaimer: These tasks are guidelines only. They do not include lockout/tagout (LOTO), energy isolation, or other safety requirements. Review and verify suitability for your specific equipment and application. Add all required safety procedures per your company's policies and regulatory requirements before use. You are responsible for the safe and appropriate execution of all maintenance activities.
Centrifugal and radial fans fail one skipped task at a time. Blade buildup throws the wheel out of balance. Bearings run dry because nobody tracked the last grease interval. Belts run glazed because tension gets eyeballed instead of measured. None of these are dramatic failures — they're just quiet deterioration that compounds until something loud happens.
This checklist covers the essential PM tasks for centrifugal and radial fan equipment — structured for field technicians executing the PM and maintenance managers building or auditing the program.
For the full picture on what actually kills fans and what your PM should be catching, start with industrial fan and blower preventive maintenance.
How to Use This Checklist
Record findings with specificity — not just a checkmark. "Bearing temp elevated" tells you nothing six months from now. "Bearing housing at 195°F, ambient 72°F — up from 178°F last PM" tells you exactly where you are in the failure curve.
Trend everything you measure. A single data point is a snapshot. Three data points is a pattern. A pattern is what justifies a corrective work order before the failure.
Know what a real finding looks like. "Belt tension OK" is a checkbox answer. "Belt deflection measured at 9/16" on a 14" span — OEM spec is 7/16", scheduled for replacement" is a finding. Write the second kind.
Field Checklist — Critical Tasks
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect fan housing exterior for cracks, dents, corrosion, or damage. Confirm access panels and guards are secure. | Every PM | MEC |
| Inspect fan wheel (impeller) for buildup, corrosion, erosion, or visible damage. Clean buildup from blades — uneven buildup causes imbalance and vibration. | Monthly | MEC |
| Inspect flexible duct connections and inlet/outlet collars for tears, gaps, or loose clamps. A leaking connection reduces system performance and can draw unfiltered air. | Quarterly | MEC |
| Verify damper blades (if installed) open and close fully and move freely without binding. Check linkage for wear or looseness. | Semi-Annually | MEC |
| Inspect shaft coupling (if direct-drive) for wear, cracking, or misalignment. Check set screws for tightness. | Semi-Annually | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Listen for abnormal noise during operation — bearing rumble, rattling, rubbing, or high-pitched squealing. Note any changes from last PM. | Every PM | MEC |
| Check drive motor for overheating — feel housing temperature or use an IR thermometer. Verify motor is within normal operating temperature. | Every PM | MEC |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect fan belt(s) for wear, cracking, glazing, or fraying. Check belt tension — deflection should be per nameplate or OEM spec. Adjust or replace as needed. | Monthly | MEC |
| Inspect sheaves/pulleys for wear, side-wall grooving, or misalignment. Verify belt is tracking in the center of the sheave groove. | Monthly | MEC |
Lubrication
| Task | Freq | Type |
|---|---|---|
| Lubricate fan shaft bearings per manufacturer specification — correct grease type, quantity, and interval. Do not over-grease. | Quarterly | MEC |
Electrical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect motor electrical connections at the terminal box for tightness, corrosion, or heat damage. Tighten any loose terminals. | Annually | ELE |
Reference Checklist — Full Task Library
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect fan housing exterior for cracks, corrosion, loose panels, or physical damage. Confirm all access covers, guards, and inlet screens are secure and undamaged. | Every PM | MEC |
| Inspect fan wheel (impeller) for blade buildup, corrosion, erosion, or cracking. Clean blades evenly — uneven buildup causes imbalance. Note any blade damage and flag for engineering review if structural. | Monthly | MEC |
| Inspect inlet cone or bell mouth for clearance to the fan wheel. Excessive gap increases turbulence and reduces efficiency. Verify clearance is within OEM tolerance. | Monthly | MEC |
| Inspect fan mounting base and isolation mounts (if installed) for cracks, deterioration, or loose anchor bolts. Anti-vibration mounts that have failed will transmit vibration into the structure. | Semi-Annually | MEC |
| Inspect flexible duct connections at fan inlet and outlet for tears, separation, or loose clamps. Check duct work for visible disconnects, air leaks, or loose supports in the immediate vicinity. | Quarterly | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Observe fan during operation for abnormal noise — bearing rumble, blade rub, belt squeal, or rattling components. Document and compare to previous PM observations. | Every PM | MEC |
| Check drive motor housing temperature using an IR thermometer. Record the reading and flag if significantly above ambient or above nameplate rating. | Every PM | MEC |
| Measure and record motor operating current on all applicable leads using a clamp meter. Compare to nameplate FLA — flag sustained readings above 90% of FLA. | Every PM | ELE |
| Verify fan rotation direction is correct relative to housing scroll and discharge orientation. A fan running backwards delivers significantly reduced flow and pressure. | Annually | ELE |
| Review and trend all recorded data from this PM cycle — motor current, housing temperature, vibration readings, bearing condition, belt condition. Document any deteriorating trends and initiate corrective action if indicated. | Annually | MEC |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect fan belt(s) for cracking, glazing, fraying, or visible wear. Measure belt deflection and compare to OEM specification — typically 1/64" per inch of span. Replace any belt showing hard cracking or glazing. | Monthly | MEC |
| Inspect sheaves and pulleys for groove wear (U-shaped groove profile indicates wear), side-wall damage, or surface scoring. Verify belt is tracking centered in the groove. Replace sheave if groove wear exceeds 1/8". | Monthly | MEC |
| Check fan shaft for radial and axial play by hand with fan de-energized and LOTO applied. Excessive movement indicates bearing wear. Compare to previous readings and flag if looseness has increased. | Quarterly | MEC |
| Verify inlet/outlet damper blades (if installed) operate through full open/close travel without binding. Inspect linkage, pivot pins, and actuator connection for wear, looseness, or corrosion. | Quarterly | MEC |
| Perform sheave/pulley alignment check using a straightedge or laser alignment tool (belt-drive units). Misaligned sheaves accelerate belt wear and increase bearing load. | Semi-Annually | MEC |
| Measure and record fan housing vibration at the bearing housings using a vibration meter or pen. Record in/s peak velocity. Flag any single measurement above 0.2 in/s or increasing trend. | Semi-Annually | MEC |
| Inspect shaft coupling (direct-drive configurations) for wear, cracking, or rubber element degradation. Check set screws for tightness. Verify coupling is within OEM misalignment tolerance. | Semi-Annually | MEC |
Lubrication
| Task | Freq | Type |
|---|---|---|
| Lubricate fan shaft bearings per manufacturer specifications — verified grease type (do not mix), correct quantity, and interval. Over-greasing a sealed bearing is a common failure cause. Record grease type, quantity, and date. | Quarterly | MEC |
Electrical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect all electrical connections at the motor terminal box — check for tightness, corrosion, heat discoloration, or chafed insulation. Re-torque terminals per OEM spec. | Annually | ELE |
| Perform insulation resistance (megger) test on motor windings per IEEE 43. Record and trend results — a reading below 1 MΩ (or a significant drop from baseline) warrants investigation. | Annually | ELE |
Failure Modes This Checklist Targets
Impeller Imbalance from Blade Buildup Process material — dust, lint, debris — accumulates on fan blades unevenly. The resulting imbalance creates vibration that accelerates bearing wear and fatigues the shaft. Cleaning blades evenly every PM is the check that prevents this.
Bearing Failure from Lubrication Errors Both under-greasing and over-greasing kill bearings. Under-greasing starves the rolling elements. Over-greasing in a sealed bearing packs the cavity and forces lubricant past the seal, leaving the bearing dry while looking well-maintained. Tracking grease type, quantity, and interval — every time — is how this gets caught.
Belt Wear and Drive Failure A glazed belt slips. A belt running on a worn sheave groove sheds cords. Either way, the fan runs at reduced speed or stops entirely. Measuring deflection instead of guessing at tension, and inspecting sheave groove profile, is the difference between catching it before it fails and replacing it after.
Motor Overheating from Overloading or Airflow Restriction A clogged inlet, a restricted duct, or a damper that won't open fully puts more load on the motor than it was sized for. The current reading and temperature check catch this before the thermal protection trips and takes the circuit down.
Structural Looseness from Isolation Mount Deterioration Isolation mounts absorb vibration. When they fail — rubber degrading, mounts compressing fully, anchor bolts backing out — the vibration transfers into the structure and into the bearing housings. The inspection catches this before it becomes a resonance problem.
Fan Running in Reverse After any electrical work, phase reversal puts the fan running backwards in the scroll housing. It moves air. Just not much of it. And the housing and bearings are loaded in a direction they weren't designed for. The rotation verification task catches this — it takes five minutes and gets skipped constantly.
