Installation of a Nite Sign Model H47B-1 Electronic Aireal Billboard.\nDATA REQUIRED:\n(1)\tNite Sign Drawing A1B, N/C dated November 18, 1978, or later "FAA Approved" revision.\n(2)\tFAA Approved Rotorcraft Flight Manual Supplement to Enstrom Helicopter Model F-28C/280 dated December 1, 1978, or later "FAA Approved" revision. View PDF on drs.faa.gov ↗

The STC PDF is authoritative: installation instructions, ICA requirements and limitations.