Thank you for choosing Aerospace-Aviation360 for Part Number 4753881 described as Line Checker, Windshield Heater System. Used To Troubleshoot And Function Check The Anti-Icing System. See Application Chart On Drawing. by Mcdonnell Douglas. This is an ASAP Semiconductor owned and operated website. We are a leading supplier of aircraft tooling parts. You have 24/7 x 365 access to our diverse product database with the fastest lead times in the industry.