The aircraft’s certification flight-test was performed by aircraft MSN1888, which completed the program in 370 flight test hours and 132 flights since its first flight in November 2018.
From the published TCDS we can tell Airbus applied for the A330-800 type certificate back on 25th July 2014, more than five years ago.
The A330-800 is part of the A330neo family. It is equiped with Rolls-Royce Trent 7000 engines, a 3D-optimised wing and new Sharklets using lighter composite materials. Together these features bring a reduction in fuel consumption of 25%, compared with older-generation aircraft such as the Boeing 767.
Certified initially with a maximum take-off weight (MTOW) of 242 tonnes, for a range capability of 7,500 nautical miles, the A330-800 will typically seat 220 to 260 passengers in three classes, or 406 travellers in a single-class high-density configuration.
To date, the A330neo Family has 337 firm orders from 22 operators.
However, the A330-800 sales have remained poor; according to Wikipedia, only a total of 14 orders have been received from Kuwait Airways, Uganda National Airlines and one undisclosed customer.
Operationally, the A330neo shares a common pilot type-rating with the larger A350 XWB; which facilitates a lower flight training cost and higher pilot productivity.