Thank you for choosing Aerospace-Aviation360 for Part Number 4750073 described as Tester, Engine Fire Detector, Portable. For Troubleshooting Edison System (Discrimination Type). 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.