Thank you for choosing Aerospace-Aviation360 for Part Number 4889798 described as Line Checker, Windshield. To Troubleshoot Heater System & Components On Eyebrow & Clear-View Windows. 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.