Yes, real parts CAN be 3D printed and even used successfully.
The printing is the easy part.
The extensive testing and validation that it will actually work as intended and in your situation is the hard part.
Skip that hard part, especially for anything that flies, and you are risking lives, both those in the air and on the ground.
Seriously, just because the specs on the label say X and other docs say the running temperature is Y, does NOT mean it will work. Take the measurements in your situation, test the thing extensively on the ground.
Then, maybe, it'll be worth flying. Or, you'll be there after some hours of testing saying: "good thing I didn't try to fly with this", and still have a usable aircraft.
The printing is the easy part.
The extensive testing and validation that it will actually work as intended and in your situation is the hard part.
Skip that hard part, especially for anything that flies, and you are risking lives, both those in the air and on the ground.
Seriously, just because the specs on the label say X and other docs say the running temperature is Y, does NOT mean it will work. Take the measurements in your situation, test the thing extensively on the ground.
Then, maybe, it'll be worth flying. Or, you'll be there after some hours of testing saying: "good thing I didn't try to fly with this", and still have a usable aircraft.
Edit: missing words, clarity.