For anyone who still remember the Y-20 2.5G destructive test and wing breaking at 120%. I just watched a video of an airline pilot talking about Boeing-777X development.
At about 15:58, he said that the wing broke at
148% (goal being 150%, 2.5G ) of its
limit load (aka ultimate load)
, the
limit load is the
maximum load that the aircraft can
legally experience.
This means that there are two load limits:
limit load(ultimate load) and
maximum operational load. Limit load is the goal (breaking point) of the 2.5G destructive test. Maximum operational load is the design specification that aircraft is allowed to pull many Gs in operation. So the final goal of 2.5G destructive test is 150% of the maximum operational load. The breaking at 120% is in reference of this 150%, in the middle of reaching 150%.
In case of Boeiing-777X, reaching 148% is deemed good enough not to necessitate a further test but with stated fixing measures. For Y-20 at 120%, I would assume further test was done untill reaching 150% (2.5G), as the engineer said in the video "this time we aim at 120%".
Regarding the CCTV report, I don't think the reporter made any mistake, it is just that the relationship of the professional terms were not presented (not that they should after all it isn't a lecture).