# NTSB LAX86LA142: Hiller 12E, N90475, Poterville, CA, March 16, 1986

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 16, 1986, 10:02 local (18:02 UTC)
- Place: Poterville, CA
- Coordinates: 35.960647, -118.919982 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.9606&lon=-118.9200&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 25093
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX86LA142
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/25093/pdf
- Page: https://openairdocs.org/ntsb/LAX86LA142

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - engine assembly - failure,total (cause)
  - engine assembly,connecting rod - failure,total (cause)
- Hard landing, landing - flare/touchdown
  - autorotation - poor, pilot in command (contributing factor)

## Analysis

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.

## Aircraft

- Registration: N90475 (not matched to a registry record)
- Reported make and model: HILLER 12E
- Category: Helicopter
- Serial number: 2366
- Engines: LYCOMING VO-540-B1A 305 horsepower reciprocating
- Damage: Substantial damage
- Flight: Positioning, Part 91
- Operator: Mark Shepard, doing business as Shepard Sprayers
- Airworthiness certificate: Special, Restricted (Special)

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 38; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 6,700 total, 600 in this make and model, 6,500 as pilot in command, 100 in the last 90 days, 60 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 225° at 5 knots
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 61 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19860316032729A](https://openairdocs.org/incident/19860316032729A), Mar 16, 1986: Hiller UH12E, Porterville, CA, Substantial damage. Engine failure due to a broken cylinder connecting rod bolt. Made a hard landing in an open field.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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