Karel Abraham hoped to use this week's pair of MotoGP tests to experiment with set-up and rebuild his confidence, after scoring just once in the opening five rounds.
Instead the Cardion AB Ducati rider suffered heavy falls at both Catalunya (Monday) and Aragon (Wednesday).
It is feared that the second accident has left the Czech rider with two broke fingers, putting his participation in next weekend's British MotoGP at Silverstone in doubt.
"We were unlucky, as in Barcelona [when Abraham fell on his out-lap on the damp track] the fall was partly my fault, but not here,” Abraham told the official MotoGP website. "Something happened with the bike, which we are trying to understand."
He added: "Actually we were doing well, but now with a hand in this conditions and the bike being destroyed, we are forced to stop the test early. Really bad luck. Now on Friday, once the hand's swelling goes down, we will perform new tests to assess my recovery time."