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4.2.1 General

(1) The blade to be tested shall be arbitrarily selected from the blades that have already been produced.

It may be the first blade produced.

(2) The blade to be tested shall be compliant with the design documentation (drawings and specifications)

that are submitted to DNV GL for certification. If local reinforcements (e.g. in the area of the load introduction zones) are necessary, this shall be agreed with DNV GL prior to testing.

(3) The blade should not be painted in order to allow for proper inspection throughout the entire test

campaign, unless specified and agreed otherwise for special purposes.

4.2.2 Test blade manufacturing

(1) The manufacturing specification for the test blade shall be documented in an as-built condition. The

documentation shall include reference to:

— blade type (name) and production number (id number, serial number) — revision of work instructions and drawings used during manufacturing — type and batch number for all materials where traceability is required — identification of worker teams responsible for each individual operation — registrations used as basis for quality control

— repairs carried out during or after the manufacturing.

(2) The manufacturing of the test blade shall be evaluated regarding the representativeness of the type to

be certified. The level of inspection has to be agreed between the manufacturer and DNV GL, and a complete and traceable production record for the test blade has to be reviewed prior to the testing. Any modifications on the test blade, including local reinforcements for load introduction, shall be documented and approved.

section [4.6], and if the effect of this tip removal on the structural behaviour of the blade and on the measurements is accurately evaluated.

4.2.3 Damage and repairs

(1) Since the test blade shall be representative for the series production, repairs which most frequently

occur during production may be applied to the test blade for validation purposes. Such repairs shall comply with the requirements of section 8, and shall be applied at areas which are sufficiently loaded; it may be required to apply increased test loads in order to account for uncertainties related to such validation.

(2) Manufacturing defects and tolerances frequently occurring during production may be applied to the test

blade for validation purposes (e.g. in connection with section [3.5.6], the related partial reduction factors from section [2.5], and section [5.5]). Such defects and tolerances shall be introduced to the blade structure at areas which are sufficiently loaded; it may be required to apply increased test loads in order to account for uncertainties related to such validation.

(3) If repairs are applied following structural damages suffered during testing, they shall be carried out in

accordance with the requirements of section 8, and evaluated according to section [4.14.3].

4.2.4 Variations in materials, design, or manufacturing methods of the

blade

(1) Full scale testing shall be carried out for all new blade types.

(2) Full scale testing shall also be carried out in case of major changes in materials, design, or

manufacturing. The following shall be considered as major changes in this respect:

— substitution of material types (such as: replacing polyester resin by epoxy resin; replacing glass fibres by carbon fibres; replacing balsa wood by PVC foam)

— major changes in structural design (such as: modified laminate or sandwich lay-up; modified ply thicknesses; modified adhesive joint design)

— changes in the geometry (such as: modified blade contour; modified shear web positioning; modified spar cap widths)

— changes in manufacturing processes (such as: replacing hand lay-up by resin infusion techniques; changes in surface preparation for adhesive joints).

(3) In case a new blade type is based on a previous blade type that has been fully tested, the scope of full

scale testing may be reduced, provided that the new blade type is the result of adjustments, improvements, or minor changes with regard to the previous blade type, or that it can be considered as part of the same blade family. E.g., a reduced scope of testing may be accepted in the following cases:

— changes affecting only those areas of the blade which are not within the scope of testing as per section [4.6], e.g. a modified blade tip shape

— substitution of a material under the same material specification (such as changing to an alternative material supplier), provided that this is properly accounted for during material qualification

— minor changes in the manufacturing processes (such as adjustments in curing cycles), provided that this is properly accounted for during material qualification (as per section [3.2.1] (3), and in connection with section [3.3.1] (3)).

Even in the case of major changes as per paragraph (2) above, a reduced scope of testing may be justified, e.g. in the following cases:

— if the changes only affect a limited area of the blade, and if it can be demonstrated that, on a previously tested blade, similar areas (i.e. similar in terms of materials, design, and manufacturing) have been sufficiently loaded

— if it can be demonstrated that the changes improve the blade strength, without significantly modifying the overall structural response and internal load distribution of the blade (such as: adding some layers to the lay-up, or replacing the sandwich core materials by a stiffer one).

tests, the pre- or post-fatigue static bending tests, or any sub-sets of these (e.g. number of test directions); or may include complete suppression of any of these. A reduced testing scope may also include intermediate level testing as per section [2.6.3]. In contrast, the scope of mass properties and natural frequency tests should not be reduced.

(5) Any reduction in the scope of testing according to paragraph (3) above shall be properly justified by

evaluating the changes in materials, design, or manufacturing with regards to the following aspects: — overall structural response of the blade, i.e. bending stiffness

— overall strain level and margins in the areas affected by the changes

— any observations from previous full scale blade testing (such as damages, or deviations from model predictions) in the affected areas.

(6) Any reduction in the scope of testing according to paragraph (3) above shall be agreed with DNV GL

prior to testing.