FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

If the piston return spring broke in a brake master cylinder, the correct answer is C - The brakes would drag. This is because without the return spring functioning properly, the piston would not fully retract after brake application, causing the brake pads to remain in contact with the rotor. As a result, the brakes would drag, leading to increased friction and potential overheating of the braking system.

Option A is incorrect because if the brakes were to lock up, it would indicate a different issue, such as a seized brake caliper or a malfunctioning anti-lock braking system.

Option B is not the correct answer because if the brakes were not operating, there would be no braking force applied when the brake pedal is depressed.

Option D is not the correct answer as the vehicle stopping immediately suggests a sudden and abrupt halt, which is not directly caused by a broken piston return spring in the brake master cylinder.