The Helicopter With Radioactive Blades
Summary
Hackaday details the CH-53 Sea Stallion’s blade health monitoring system that uses a small amount of radioactive Strontium-90 (Sr-90) in the Inflight Blade Monitoring System (IBIS) to detect cracks. The article explains how the system avoids wiring through the rotor by using a radioactive indicator read by a cockpit Geiger counter, notes that older blades relied on nitrogen-filled, pressurized spars, and mentions that newer designs employ fiber-optic sensing while the radioactive approach remains in some models. It also touches on safety considerations and disposal concerns, with reader comments discussing radiation risk and historical context.