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NTSB Report

January 2, 1988 · Hiller UH-12E · N400AH

Vernal, UT

Overview

Report Status

Preliminary report

Event Type

Accident

Date

January 2, 1988

Injury Outcomes

No injuries (3 uninjured)

Location

Vernal, UT

Aircraft

Hiller UH-12E

Tail Number

N400AH

Operator

Dynamic Aviation

Injuries

None

Aircraft Damage

Substantial

NTSB Number

DEN88LA046

THE COMMERCIAL PLT AND TWO PASSENGERS WERE SURVEYING A ROAD ROUTE IN MOUNTAINOUS TERRAIN. AT CRUISE, THE PILOT NOTICED A DROP IN MANIFOLD PRESSURE, FOLLOWED BY A LOSS OF OIL PRESSURE. THE PLT REPORTED THAT THE ENGINE QUIT. AN AUTOROTATION TO A SNOW COVERED ROAD RESULTED IN A HARD LANDING. THE MAIN ROTOR BLADES SEVERED THE TAIL BOOM AND THE LANDING SKIDS COLLAPSED. A POST ACCIDENT ENGINE TEAR DOWN REVEALED EVIDENCE CONSISTENT WITH CONNECTING ROD FAILURE. THE NUMBER FIVE ROD BEARING HAD DISINTEGRATED AND THE ROD END CAP HAD BROKEN IN SERVICE. THE DAMAGED ROD END CAP AND CONNECTING ROD WERE EXAMINED FOR FAILURE MODE DETERMINATION. THE METALLURGIST'S FACTUAL REPORT STATES THAT THE ROD SHOWS FRACTURE DETAILS CHARACTERISTICS OF HIGH CYCLE FATIGUE.

Full Narrative

THE COMMERCIAL PLT AND TWO PASSENGERS WERE SURVEYING A ROAD ROUTE IN MOUNTAINOUS TERRAIN. AT CRUISE, THE PILOT NOTICED A DROP IN MANIFOLD PRESSURE, FOLLOWED BY A LOSS OF OIL PRESSURE. THE PLT REPORTED THAT THE ENGINE QUIT. AN AUTOROTATION TO A SNOW COVERED ROAD RESULTED IN A HARD LANDING. THE MAIN ROTOR BLADES SEVERED THE TAIL BOOM AND THE LANDING SKIDS COLLAPSED. A POST ACCIDENT ENGINE TEAR DOWN REVEALED EVIDENCE CONSISTENT WITH CONNECTING ROD FAILURE. THE NUMBER FIVE ROD BEARING HAD DISINTEGRATED AND THE ROD END CAP HAD BROKEN IN SERVICE. THE DAMAGED ROD END CAP AND CONNECTING ROD WERE EXAMINED FOR FAILURE MODE DETERMINATION. THE METALLURGIST'S FACTUAL REPORT STATES THAT THE ROD SHOWS FRACTURE DETAILS CHARACTERISTICS OF HIGH CYCLE FATIGUE.

Flight

Event TypeAccident

Event Time15:30 MST

Nearest Airport0nm N

Runway0

Runway Length0

Runway Width0

Flight Plan FiledNone

Aircraft FireNo

Aircraft ExplosionNo

Aircraft

AircraftHiller UH-12E

Tail NumberN400AH

Aircraft CategoryHeli

DamageSubstantial

OperatorDynamic Aviation

Operating RulePart 91

Engines1

Engine TypeReciprocating

Engine DetailsLycoming · TIVO-540-A2A · Reciprocating · 315

Seats4

People & Injuries

Injury SummaryNo injuries (3 uninjured)

Fatal0

Serious0

Minor0

Uninjured3

Total3

Crew 1Age 35 · Second Class

Conditions

ConditionsVMC

LightDaylight

Wind230°

Visibility50 sm

CeilingNone

Temperature / Dew Point5 C / 0 C

Altimeter0

Observation Time16:48

Weather SourcePILO

500 – Data service is offline

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January 2, 1988 · Hiller UH-12E · N400AH

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