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NTSB Report
March 16, 1986 · Hiller 12E · N90475
Poterville, CA
Overview
Report Status
Preliminary report
Event Type
Accident
Date
March 16, 1986
Injury Outcomes
No injuries (1 uninjured)
Location
Poterville, CA
Aircraft
Hiller 12E
Tail Number
N90475
Operator
Mark Shepard
Injuries
None
Aircraft Damage
Substantial
NTSB Number
LAX86LA142
A HILLER 12E HELICOPTER LANDED HARD AFTER AN ENG FAILURE. THE ACFT WAS ENROUTE TO ANOTHER FIELD SITE AT APRX 100 FT AGL AND 40 KTS IAS. THE ENG QUIT ABRUPTLY AND THE ROTOR RPM DECAYED 100 RPM. THE ACFT WAS ABOUT 2,000 POUNDS GWT AT THE TIME OF THE ACCIDENT AND THE AUTOROTATIONAL RPM WAS RIGGED FOR THE MAXIMUM GWT OF 3,100 POUNDS. THE ENG MAIN CASE WAS CRACKED IN THE VICINITY OF CYL #6. DURING THE ENG TEARDOWN #6 PISTON, CONNECTING ROD AND ONE RODCAP BOLT CAME OFF WITH THE CYL. ONE ROD BOLT WAS BROKEN AND THE NUT WAS STILL ATTACHED TO THE BROKEN END. THE OTHER ROD BOLT WAS UNBROKEN AND THE NUT WAS MISSING.
Full Narrative
A HILLER 12E HELICOPTER LANDED HARD AFTER AN ENG FAILURE. THE ACFT WAS ENROUTE TO ANOTHER FIELD SITE AT APRX 100 FT AGL AND 40 KTS IAS. THE ENG QUIT ABRUPTLY AND THE ROTOR RPM DECAYED 100 RPM. THE ACFT WAS ABOUT 2,000 POUNDS GWT AT THE TIME OF THE ACCIDENT AND THE AUTOROTATIONAL RPM WAS RIGGED FOR THE MAXIMUM GWT OF 3,100 POUNDS. THE ENG MAIN CASE WAS CRACKED IN THE VICINITY OF CYL #6. DURING THE ENG TEARDOWN #6 PISTON, CONNECTING ROD AND ONE RODCAP BOLT CAME OFF WITH THE CYL. ONE ROD BOLT WAS BROKEN AND THE NUT WAS STILL ATTACHED TO THE BROKEN END. THE OTHER ROD BOLT WAS UNBROKEN AND THE NUT WAS MISSING.
Flight
Event TypeAccident
Event Time10:02 PST
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftHiller 12E
Tail NumberN90475
Aircraft CategoryHeli
DamageSubstantial
OperatorMark Shepard
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · VO-540-B1A · Reciprocating · 305
Seats3
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 38 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind225° @ 5 kt
Visibility30 sm
CeilingNone
Temperature / Dew Point61 F / 0 C
Altimeter0
Weather SourcePILO