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Aviation Accident

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NTSB Identification: CEN18FA259
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Saturday, July 07, 2018 in Chicago, IL
Aircraft: EUROCOPTER DEUTSCHLAND GMBH EC135P1, registration: N312SA
Injuries: 1 Serious, 2 Minor, 1 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

On July 7, 2018, about 2123 central daylight time, an Eurocopter Deutschland GMBH EC135 P1 helicopter, impacted terrain during an autorotation following a dual engine failure while maneuvering near Chicago, Illinois. The pilot and paramedic sustained minor injuries, the flight nurse sustained serious injuries, and the patient was not injured during the accident. The helicopter sustained substantial damage to the fuselage, tailboom, and main rotor blades. The helicopter was owned by Bennett Aviation, LLC, Elmhurst, Illinois, and operated by Pentastar Aviation Charter under the provisions of 14 Code of Federal Regulations Part 135 as an air ambulance flight. Night visual meteorological conditions prevailed at the time of the accident, and the flight was operated under a visual flight rules flight plan. The flight departed St. Mary Medical Center, Hobart, Indiana, at 2110, and was destined for Advocate Christ Medical Center, Oak Lawn, Illinois.

Preliminary satellite tracking and air traffic control information revealed the helicopter was traveling northwest from the St. Mary Medical Center on a direct route to Advocate Christ Medical Center about 1,000 ft above ground level. About 5 miles southeast of Advocate Christ Medical Center, the helicopter turned to the right after the pilot requested to return to the Gary, Indiana, airport. About 50 seconds later, the pilot declared a "mayday" and stated the helicopter was going down into a field. The helicopter came to rest upright in a grass area between the Interstate 94 and Interstate 57 interchange.

Surveillance video from a Chicago Transit Authority rail platform located adjacent to the accident site depicted the helicopter during the final phase of the autorotation and impact with terrain. The video showed a fire near the number 2 (right) engine during the autorotation. A explosion was observed after the impact with terrain.

Postaccident examination of the accident site revealed the initial impact was consistent with the fenestron skid cap contacting the terrain first, followed by the landing gear skids and fuselage. The left landing gear skid was separated and came to rest near the ground scar consistent with the fuselage. The fuselage was crushed upward, and the fenestron assembly was separated at the tailboom attachment location (see Figures 1 and 2). The pilot seat, paramedic seat, and flight nurse seat were found fully attenuated. Thermal damage was noted on the right engine and main transmission cowling. Both engines power turbine wheel blades were missing the outer halves of the blades. Multiple impact dents, consistent with the fractured turbine blades, were noted inside the exhaust stubs. The No. 1 engine had a 1/2" by 1/2" hole in the exhaust stub at the 2 o'clock position forward of the aft firewall, and the No. 2 engine had a 2" by 1" hole in the exhaust stub at the 11 o'clock position forward of the aft firewall.

The helicopter was equipped with an Outerlink IRIS video, voice, flight data, and satellite communications system. The IRIS equipment was removed and sent to the NTSB Vehicle Recorder laboratory for video, voice, and data extraction.