A Piper M-series airplane used by ZeroAvia as a flying testbed for its hydrogen propulsion system crashed on April 29, 2021, after electrical power was lost to both of its motors, according to a just-released final report from the UK Air Accident Investigation Branch (AAIB). The report notes that an emergency procedure to clear an inverter lockout proved to be ineffective and that the company failed to carry out an investigation of previous loss-of-power incidents also caused by inverter lockouts during three flights before the accident near Cranfield Airport in England.
In their summary of factors contributing to the nonfatal accident, in which the aircraft was badly damaged after a crash landing in a field, AAIB investigators said ZeroAvia’s flight-test team did not review the risk assessment of the testing following the loss of propulsion on previous flights. “Ad hoc changes were made to the flight test plan, including the position where the electrical power source was switched, without the knowledge of the competent person,” they concluded.
“We have embedded key learnings into both our organizational culture and structure, as well as our future technical designs,” the California-based startup said.
The report was published as ZeroAvia prepares to make the first test flight of its fuel cell-based powertrain on a Dornier Do-228 later this week from its UK base at Kemble.
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