Propeller flaw faulted for Vertical’s Aug. 9 eVTOL air taxi plunge

UK air taxi developer Vertical Aerospace has revealed the cause of the August 9 crash of its VX4 electric vertical takeoff and landing (eVTOL) prototype aircraft, and said it has already begun moving toward resumed test flights and planned certification in 2026.

London-based Vertical announced the results of its internal investigation into the incident, during which its prototype air taxi sustained considerable damage during a stress test hover flight when it dropped from what witnesses said was a height of about 20 feet to the tarmac. The relatively rapidly obtained findings stated the cause was “a fault with a propeller” that led to the eVTOL coming down hard during the tethered trial.

Read: Vertical’s laconic response to air taxi crash will only add to its woes

As virtually all companies tend to do in managing troubling events, Vertical presented its results in a forward-looking manner. It noted the early generation eVTOL component responsible for the problem had “already been redesigned prior to the incident,” with the update to the system slated for implementation “ahead of the next phase of testing” of the prototype air taxi.

Vertical stated that up to that point, “(p)erformance targets were generally exceeded by 10-30% during hover and low speed flights” during VX4 air taxi testing since they began last September. It also noted that the eVTOL’s incident arose during trials specifically designed to challenge the craft under exceptional conditions, and “understand how the aircraft performed outside of its expected operating conditions before the aircraft’s planned retirement.”

The startup has submitted its findings to the UK’s Air Accidents Investigation Branch (AAIB) for independent inquiry, and awaiting what it expects to be confirmation of its results is moving ahead with its plans to develop the plane toward expected 2026 certification and launch. 

As part of that effort, Vertical said it has already commenced assembly of “a second significantly more advanced full-scale VX4 prototype,” with that demonstrator eVTOL expected be completed early next year. A full-scale, flight-approved version of that air taxi is slated to take to the skies in the second half of 2024.

Read: UK air taxi maker Vertical reveals first untethered eVTOL test flight

Despite the truly bad PR (and, it must be said, less than ideal transparency Vertical demonstrated) as news of the air taxi crash circulated earlier this month, company CEO Stephen Fitzpatrick is still enthusiastic about the VX4 eVTOL’s broader fortunes.

“We are pleased with our flight test progress to date and the data, insights, and invaluable learnings we have collected,” Fitzpatrick said. “While a fault of any sort is disappointing, it is not wholly unexpected at this stage of testing a novel aircraft. I am pleased that as a result of our expert team we have isolated the cause of the fault and been able to provide the AAIB with our report within 14 days of the incident. Our planned second upgraded prototype, which will include most of our top tier partners’ technology, will have us in the air early next year and we remain on track for our certification timelines”.