Part B - Certificates and approval requirements 
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• Functional tests and test of the safety system 
• Corrosion protection 
• Check for damage 
A test report shall be prepared after completion of the commissioning inspection 1 '. 
6.5 Periodical inspections 
6.5.1 General 
The entire system (turbine and support structure) shall be inspected in detail as part of the periodical 
inspections. A specific checklist for the facility and site shall be prepared for the test on the basis of the 
technical documents, and shall also contain the evaluation criteria. The intervals for recurrent tests shall 
be defined. Periodical inspections shall be performed annually on 25% of the offshore wind farms of an 
offshore wind farm, so that all offshore wind turbines will have been inspected after each block of four 
years. Central structures such as the transformer substation shall be inspected annually, whilst deviation 
from the annual inspection is permitted for other individual structures. The inspection shall be performed 
by suitable experts. 
6.5.2 Evaluation criteria for the periodical inspections 
The evaluation criteria for periodical inspections shall be defined with regard to the structure and site. 
6.5.3 Documents of the offshore wind turbines to be tested 
The following documents at least shall be inspected as part of the periodical inspections: 
• Test reports or certification reports with all appendices and supplements 
• Construction approval 
• Operating permit 
• Operating instructions 
• Commissioning report 
• Filled-in technical maintenance specifications for the offshore wind farm including the support struc 
ture and scour protection (maintenance logs) 
• Reports on previous recurrent tests or condition inspections 
• Certificate of the oil quality 
• Documentation of modifications/repairs made to the installation and, if necessary, approvals 
6.5.4 Scope of the periodical inspections 
A visual inspection of the installation shall be performed involving inspection of the individual installation 
components including the rotor blade and the underwater structure as well as the scour protection from 
immediate proximity, the underwater structure shall be inspected by divers or with a camera mounted 
on a remotely operated vehicle (ROV). The points to be inspected shall be cleaned or exposed as re 
quired. 
1) Note: Commissioning inspection is important not just from the perspective of reliability and safety of the offshore wind tur 
bine. Following commissioning, the standard procedure is for ownership and responsibility to be transferred from the manu 
facturer to the operator/owner. Checking the condition of the system provides a certificate from an independent body stating 
that the offshore wind turbine is in correct condition.