NTSB Identification: CHI90FA118.
The docket is stored on NTSB microfiche number 42572.
Accident occurred Saturday, April 28, 1990 in SOUTHFIELD, MI
Probable Cause Approval Date: 12/14/1992
Aircraft: SIKORSKY S-58F, registration: N871
Injuries: 1 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.

THE HELICOPTER WAS HOVERING IN PLACE DURING A ROOFTOP EQUIPMENT REMOVAL OPERATION WHEN IT ABRUPTLY DESCENDED ONTO THE STRUCTURE FROM WHICH THE LIFT WAS BEING MADE. IT THEN NOSED OVER THE STRUCTURE & IMPACTED APRX 10 FT BELOW ON THE ROOF OF THE 15TH FLOOR. THE WORKERS HEARD NO VERBAL WARNING FROM THE PILOT. ACOUSTICAL ANALYSIS OF A VIDEO REVEALED THAT DURING THE DESCENT THERE WAS A STEADY INCREASE IN ENGINE, M/R, AND T/R RPM. POST MORTEM EXAM OF THE PILOT REVEALED FOCAL ATHEROSCLEROSIS 50% LEFT AND RIGHT CORONARY ARTERY, LEFT ANTERIOR DESCENDING, AND LEFT CIRCUMFLEX. THE PILOT & CREW HAD OPERATED TOGETHER AS A TEAM FOR 18 YRS & THE CREW STATED THAT THE PILOT, WITH NO EXCEPTIONS, HAD ALWAYS NOTIFIED THEM BY RADIO WHEN UNEXPECTED OCCURRENCES CAUSED PREMATURE RELEASES.

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

A LOSS OF CONTROL DUE TO PHYSICAL INCAPACITATION FOR UNKNOWN REASON(S).

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