The first CSeries test aircraft has re-entered a series of ground vibration checks less than a month after completeing first flight, Bombardier revealed today.

A nearly 3min clip posted on the company’s YouTube channel on 16 October provides the first update on the test programme since the first test aircraft (FTV-1) stopped flying on 3 October.

The video shows the FTV-1 test aircraft parked inside a hangar and covered in test instruments.

Alexandre Rathé, a structure dynamic engineer for Bombardier, says on the video that the aircraft is undergoing ground vibration testing.

The aircraft is suspended off the floor of the hangar to simulate a flight situation, he says. About 400 accelerometers attached to the airframe measure vibrations created by oscillations applied to areas such as the wingtips and the engine.

“Ultimately with the input that we’ve created we’ll be able to determine the modes of vibration of the aircraft,” Rathé says.

It was not immediately clear why the tests are necessary. Bombardier announced last June that the FTV-1 aircraft had completed ground vibration testing, a necessary step in clearing the aircraft for first flight. Bombardier has not responded to requests for an update on the test programme.

Rathé says the new round of tests will help the programme move forward.

“Some adjustments may be necessary on our finite element models,” Rathé says. “These [vibration] modes are very important from a dynamic point of view and they will predict the aircraft’s flight stability, so it’s very important to measure and model them properly.”

The CSeries completed the first flight test in Montreal one month ago, and has been airborne only two more times since.

Bombardier is targeting to complete airworthiness testing in 11 months, including about 2,500h of flight testing.