# NTSB MIA93LA125: Hiller UH-12C, N46937, Sarasota, FL, May 20, 1993

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: May 20, 1993, 16:18 local (20:18 UTC)
- Place: Sarasota, FL
- Coordinates: 27.250808, -82.380973 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=27.2508&lon=-82.3810&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 3, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 33271
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA93LA125
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/33271/pdf
- Page: https://openairdocs.org/ntsb/MIA93LA125

## Probable cause

THE PILOT-IN-COMMAND'S IMPROPER APPLICATION OF THE FLIGHT CONTROLS DURING AN AUTOROTATIVE LANDING, RESULTING IN AN IN-FLIGHT COLLISION WITH WIRES AND TERRAIN. CONTRIBUTING TO THE ACCIDENT WAS THE IMPROPER INSPECTION OF THE ENGINE FUEL SYSTEM (CARBURETOR) BY MAINTENANCE PERSONNEL, RESULTING IN A CONTAMINATED CARBURETOR AND A PARTIAL LOSS OF ENGINE POWER WHILE IN CRUISE FLIGHT.

## Sequence of events

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

- Loss of engine power(partial) - nonmechanical, cruise - normal
  - fuel system,carburetor - contamination (contributing factor)
  - maintenance,service bulletin/letter - not performed, other maintenance personnel (contributing factor)
  - maintenance,inspection - not performed, other maintenance personnel (contributing factor)
- Forced landing, descent - emergency
- In flight collision with object, descent - emergency
  - object - wire,static
  - flight controls - improper use of, pilot in command (cause)

## Analysis

THE COMMERCIAL PILOT WAS IN CRUISE FLIGHT AT ABOUT 400 FEET AGL WHEN HE OBSERVED A SUDDEN DROP IN ENGINE RPM FOLLOWED BY AN INCREASE IN RPM. THE PILOT INITIATED A FORCED LANDING BY ENTERING AN AUTOROTATION. DURING THE DECELERATION THE HELICOPTER COLLIDED WITH POWER LINES AND CRASHED. REVIEW OF THE HELICOPTER LOGBOOKS REVEALED THE CARBURETOR FLOAT ASSEMBLY HAD NOT BEEN CHANGED, AND NUMEROUS SERVICE BULLETIN PROCEDURES PERTAINING TO THE MA 4-5 CARBURETOR HAD NOT BEEN PERFORMED. DISASSEMBLY INSPECTION OF THE CARBURETOR REVEALED THE CARBURETOR WAS CONTAMINATED. SAND WAS PRESENT IN THE CARBURETOR BOWL, THE FUEL INLET ASSEMBLY WAS DIRTY AND THE PUMP PLUNGER ASSEMBLY WAS RUSTY.

## Aircraft

- Registration: N46937 (not matched to a registry record)
- Reported make and model: HILLER UH-12C
- Category: Helicopter
- Serial number: 862
- Airframe hours: 4308
- Engines: FRANKLIN 6V335 210 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Jocher, Arthur H.
- Registered owner: Jocher, Arthur H.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 10, 1993, 12 hours before
- Departed: NONE
- Destination: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 2,068 total, 158 in this make and model, 1,099 as pilot in command, 61 in the last 90 days, 22 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 260° at 9 knots
- Lowest ceiling: none
- Temperature: 82 °F, dew point 70 °F
- Altimeter: 29.00 inHg
- Observed at: SRQ, 2 nm away

## 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 19930520014619A](https://openairdocs.org/incident/19930520014619A), May 20, 1993: Hiller UH12C, Sarasota, FL, Substantial damage. Surging engine. Struck wires on precautionary landing. Sand,dirt and rust in carburetor. Service bulletin not done.

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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