NTSB Identification: CHI88FA190.
The docket is stored on NTSB microfiche number 40175.
Accident occurred Tuesday, August 02, 1988 in BRACEVILLE, IL
Probable Cause Approval Date: 01/31/1990
Aircraft: MCDONNELL DOUGLAS 269B, registration: N9522F
Injuries: 2 Fatal.

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.

AT 1903 CDT ON 8/2/88, THE FLT DEPARTED AURORA, IL, ON A LOCAL FISHING TRIP. AT APRX 1930, IT WAS SEEN IN THE VICINITY OF CARBON HILL, IL. WHEN IT DID NOT RETURN FROM THE FISHING TRIP, A SEARCH WAS INITIATED. IT WAS FOUND ON 8/4/88 WHERE IT CRASHED NEAR A COOLING LAKE NEAR A NUCLEAR POWER PLANT. AN EXAM OF THE WRECKAGE REVEALED THE HELICOPTER HAD IMPACTED IN A NEAR VERTICAL DESCENT. THERE WAS EVIDENCE THE HELICOPTER WAS IN AN UPRIGHT ATTITUDE WHEN IT CRASHED. DRG IMPACT, THE CRUSH LINE MOVED UPWARD FROM THE SKIDS INTO THE BOTTOM OF THE CABIN. THE SEATS & TAILBOOM FAILED IN A DOWNWARD DIRECTION. ALL OF THE MAIN ROTOR BLADES REMAINED ATTACHED TO THE MAIN ROTOR HEAD ALTHOUGH THEY HIT THE GROUND DRG IMPACT. NO PREIMPACT PART FAILURE OR MALFUNCTION OF THE AIRFRAME OR ENG WAS FOUND DRG THE INVESTIGATION.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

CONDUCTING MANEUVERING FLIGHT THE PIC FAILED TO MONITOR THE HELICOPTER SYSTEMS AND ALLOWED THE MAIN ROTOR RPM TO DECAY TO THE POINT WHERE IT WOULD NOT PRODUCE ENOUGH LIFT TO SUSTAIN FLIGHT.

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