A method of using non-destructive ultrasonic test equipment to assess the integrity of an adhesive bond between a flange extender of a structural web assembly of a wind turbine blade and a shell (30, 31) of a wind turbine blade, the structural web assembly comprising: a web member having a web portion and a flange portion extending away from the web portion, wherein the web member comprises a heel of substantially curvilinear form located between the web portion and the flange portion; and a flange extender integrated with the flange portion of the web member, wherein a first section of the flange extender overlies the flange portion and a second section of the flange extender extends past the heel and away from the web portion of the web member; the method comprising: using non-destructive ultrasonic test equipment to identify first and second target surfaces of the structural web assembly, wherein the first and second target surfaces are spaced from one another by an intermediate region in which it is not possible to positively identify any surface using the non-destructive ultrasonic test equipment, wherein positive identification of the first and second target surfaces is indicative of a good integrity bond in the intermediate region, and wherein positive identification of only one, or neither, of the target surfaces (16, 45) is indicative of a poor integrity bond in the intermediate region; wherein the first target surface is identified as being an inner surface of the flange portion of the structural web assembly and the second target surface is identified as being an inner surface of the flange extender; and wherein the intermediate region is identified as corresponding to the vicinity of the heel of substantially curvilinear form of the structural web assembly. a web member having a web portion and a flange portion extending away from the web portion, wherein the web member comprises a heel of substantially curvilinear form located between the web portion and the flange portion; and a flange extender integrated with the flange portion of the web member, wherein a first section of the flange extender overlies the flange portion and a second section of the flange extender extends past the heel and away from the web portion of the web member; the method comprising: using non-destructive ultrasonic test equipment to identify first and second target surfaces of the structural web assembly, wherein the first and second target surfaces are spaced from one another by an intermediate region in which it is not possible to positively identify any surface using the non-destructive ultrasonic test equipment, wherein positive identification of the first and second target surfaces is indicative of a good integrity bond in the intermediate region, and wherein positive identification of only one, or neither, of the target surfaces (16, 45) is indicative of a poor integrity bond in the intermediate region; wherein the first target surface is identified as being an inner surface of the flange portion of the structural web assembly and the second target surface is identified as being an inner surface of the flange extender; and wherein the intermediate region is identified as corresponding to the vicinity of the heel of substantially curvilinear form of the structural web assembly. using non-destructive ultrasonic test equipment to identify first and second target surfaces of the structural web assembly, wherein the first and second target surfaces are spaced from one another by an intermediate region in which it is not possible to positively identify any surface using the non-destructive ultrasonic test equipment, wherein positive identification of the first and second target surfaces is indicative of a good integrity bond in the intermediate region, and wherein positive identification of only one, or neither, of the target surfaces (16, 45) is indicative of a poor integrity bond in the intermediate region; wherein the first target surface is identified as being an inner surface of the flange portion of the structural web assembly and the second target surface is identified as being an inner surface of the flange extender; and wherein the intermediate region is identified as corresponding to the vicinity of the heel of substantially curvilinear form of the structural web assembly.