Representative case · 03
Yaw hunting: the nacelle swings back and forth
In gusty wind the nacelle keeps reversing; rhythmic knocking, hourly yaw count far above neighbours.
Representative case. This page describes a fault pattern that is common in the field, as a diagnostic sequence. It does not describe a specific wind farm, turbine or date; numbers are examples only and limits vary by turbine type. On your own turbine the OEM instructions, LOTO procedure and safety rules apply; work near energised equipment is for authorised personnel only.
Symptom
In gusty wind the nacelle keeps reversing; rhythmic knocking, hourly yaw count far above neighbours.
What was measured
Wind direction signal offset and noisy compared with neighbours; yaw brake residual pressure below its lower limit.
Root cause
A loose wind vane, weak brake holding and late bearing lubrication — together.
Fix and verification
Vane tightened and realigned, brake leak fixed and pressure set, bearing lubricated.
Lesson
Hunting rarely has a single cause; check sensors and mechanics before suspecting parameters.
Full version
The complete diagnostic sequence — possible causes table, step-by-step checks, maintenance checklist and common mistakes — is in the Turkish version of this case.