What happened
On April 15, 2019, at 0351 EDT, a Bell 206-L1+ helicopter, registration N395AE, was performing an emergency medical services flight near the Fairview Park Hospital Heliport (48GA) in Dublin, Georgia. The crew, consisting of a pilot, flight nurse, and paramedic, intended to transport a patient from Macon to Augusta.
After completing a preflight inspection and a normal engine start, the pilot transitioned the aircraft into a hover and prepared for an altitude over airspeed takeoff. As the helicopter began to accelerate and gain climbout speed, the pilot heard a loud report from the engine deck area, followed by a clicking noise. The helicopter immediately began to descend, impacting the ground and bouncing before coming to rest upright. The pilot was not injured, and there were no fatalities or other injuries among the crew.
The investigation
Post-accident examination of the aircraft showed that the skids were spread and the vertical fin had been severed by contact with the main rotor blades. Fuel samples showed no signs of water or debris, and the engine intake was clear of foreign objects.
During the examination of the Rolls Royce M250-C30P engine, investigators found that the compressor module's diffuser had separated into two sections, exposing the vanes. A metallurgical examination by the NTSB Materials Laboratory determined that the ring section had separated through the braze joint at the forward interfaces of the vanes. The study revealed that the braze joints were compromised by incomplete filler metal wetting; specifically, orange paint was found on the vane cross-sections where the braze metal had failed to bond to the base metal.
Records indicated the diffuser was a parts manufacturing approval (PMA) component. The manufacturing history of the part was unavailable due to the 10-year record retention policies of the involved companies. The diffuser had been installed in the engine approximately 13 years prior and had accumulated 5,763.1 hours of use since its installation.