NTSB Identification: CHI82FA304
14 CFR Part 91: General Aviation
Accident occurred Thursday, August 12, 1982 in WISCONSIN DELLS, WI
Probable Cause Approval Date: 08/12/1983
Aircraft: HILLER UH12L4, registration: N3748Z
Injuries: 1 Serious,1 Minor,1 Uninjured.
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.
DURING CLIMB, AT ABOUT 200 FT AGL, THE M/R LOST RPM. DURING AUTOROTATION THE ENG RPM INCREASED BEYOND THE RED LINE WHEN THE PLT ADDED POWER. THE HELICOPTER MADE A HARD LANDING IN A RESIDENTIAL AREA. INSPECTION OF THE MERCURY CLUTCH REVEALED THAT THE EXTERIOR SURFACE OF THE CLUTCH DRUM EXHIBITED EVIDENCE OF EXCESSIVE OVERHEATING. THE INSIDE SURFACE OF THE DRUM SHOWED SEVERE GLAZING & DISCOLORATION IN THE CLUTCH SHOE WEAR AREA. THERE WERE ALSO SEVERAL CRACKS IN THE CLUTCH DRUM. THE HOUSING BEARING JOURNAL HAD EXPERIENCED SEVERE PITTING. THERE WAS ALSO SEVERE WEAR IN THE BEARING JOURNAL AREA. THE CLUTCH SHOES SHOWED SIGNIFICANT GLAZING & SURFACE CRACKING, & WERE SEVERELY WORN.
The National Transportation Safety Board determines the probable cause(s) of this accident to be:ROTOR DRIVE SYSTEM,CLUTCH ASSEMBLY..WORN
The National Transportation Safety Board determines the probable cause(s) of this accident to be:ROTOR DRIVE SYSTEM,CLUTCH ASSEMBLY..FAILURE,TOTAL
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