§61.159 Aeronautical experience: Airplane category rating.
(a) Except as provided in paragraphs (b), (c), and (d) of this section, a person who is applying for an airline transport pilot certificate with an airplane category and class rating must have at least 1,500 hours of total time as a pilot that includes at least:
I think this can be any Category
(5) 250 hours of flight time in an airplane as a pilot in command, or as second in command performing the duties of pilot in command while under the supervision of a pilot in command, or any combination thereof, which includes at least—
(i) 100 hours of cross-country flight time; and
(ii) 25 hours of night flight time.
This has to be in an Airplane.
(c) A commercial pilot may credit the following second-in-command flight time or flight-engineer flight time toward the 1,500 hours of total time as a pilot required by paragraph (a) of this section:
(1) Second-in-command time, provided the time is acquired in an airplane
So Second in Command time must be in an Airplane to be counted towards the 1500 total time.
Does this mean that all of my helicopter Co-Pilot, Dual and Other time does not count towards the 1500h total?
Yes, except that "Dual" means what? In FAA parlance you can log PIC time while receiving dual instruction if you are the sole manipulator of the controls.