For the first test flight of an aircraft, it's quite common to test a very limited set of parts of the aircraft, and retracting the gear might not be on that li

For the first test flight of an aircraft, it's quite common to test a very limited set of parts of the aircraft, and retracting the gear might not be on that list. Also, if the gear is left down, then that's one less thing that could go wrong while the pilot is still getting used to an aircraft with a very different feel to anything they have flown before.