The explanations offered on this thread largely track with the info generated during restoration of Doug Champlin's gorgeous N.28 in Arizona. The Type 28 was the first Nieuport design produced in numbers that was not a sesquiplane/V-strutter. Despite the novelty of the 28 configuration within the Nieup. organization, there was insufficient testing of the design, and there were also questions about quality of material and workmanship. In any case, the leading-edge extension was source of the problem rather than
EVR's oft-quoted report fingering the fabric attachment.
Builder/restorer/test pilot Jim Appleby opined that a properly arranged 28 could be safely dived at 200 mph.