R-Pro › Field cases › Air conditioning
Outdoor Fan Blade Crack/Break (Vibration → Shaft Imbalance → Motor Bearing Damage)
Likely causes
Blade fatigue crack or foreign object impact → immediate imbalance
Check: Power off and perform full visual blade inspection: hold up to light and check root-to-tip for cracks — replace if cracks are ≥0.5mm. Measure housing vibration during operation — ≤3mm/s is normal.
What to do: Replace blade: apply specified torque with torque wrench (typically 5–8N·m) to hub bolt. Static balance check: place on horizontal jig and verify weight deviation ≤10g. Simultaneously inspect motor bearing. On first startup after replacement, stand back ≥3m and observe 1 minute — flying broken blade is lethal.
Poor installation — hub bolt under-torqued causing slip and eccentric rotation
Check: Check hub bolt with torque wrench — if below specified torque (5–8N·m), tighten immediately. Check for slip marks (scratches) between blade hub and motor shaft.
What to do: Re-tighten to specified torque. If slip marks present, check hub or motor shaft for damage — replace parts if heavily damaged. Re-measure vibration after restart.
Before first startup in spring after winter shutdown, mandatory blade visual inspection — cold-temperature brittle fracture is common. Blades used outdoors for 5+ years risk UV-degraded surface cracks.
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