# NTSB CEN23LA383: Hiller UH-12A, N8178H, Mosby, MO, August 27, 2023

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 4 · Limited · Final report
- Date: August 27, 2023, 18:00 local (23:00 UTC)
- Place: Mosby, MO · On airport ramp area.
- Coordinates: 39.332508, -94.309648 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.3325&lon=-94.3096&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-hover: Loss of control in flight](https://openairdocs.org/ntsb-events/240)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Central Region
- Parties: FAA
- NTSB case key (mKey): 192949
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN23LA383
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192949/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192949
- Page: https://openairdocs.org/ntsb/CEN23LA383

## Probable cause

The pilot’s failure to maintain adequate rotor rpm which resulted in a loss of control and impact with terrain.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Hiller UH-12A, 1 case](https://openairdocs.org/ntsb-findings/01062050/cases.md?model=4360104), [All aircraft, 81 cases](https://openairdocs.org/ntsb-findings/01062050/cases.md)
- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Hiller UH-12A, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=4360104), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)
- [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Hiller UH-12A, 2 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=4360104), [All aircraft, 894 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Maneuvering-hover: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Hiller UH-12A, 3 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=4360104), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md)
- [Taxi: Ground collision](https://openairdocs.org/ntsb-events/200); cases with it: [Hiller UH-12A, 1 case](https://openairdocs.org/ntsb-events/200/sequence.md?model=4360104), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md)

## Analysis

The pilot reported that during a hover taxi, he inadvertently allowed the engine rpm to decrease. He increased the throttle, but the helicopter landed hard on its skids in the grass and the tail rotor impacted the ground. The ground strike resulted in substantial damage to the tail rotor blades and tailboom assembly. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The pilot noted that a better scan of the engine instruments could have prevented the accident.

## Aircraft

- Registration: [N8178H](https://openairdocs.org/aircraft/N8178H), registered now, S/N 178, built 1950 (OpenAirDocs)
- Reported make and model: HILLER UH-12A
- Registry model: [Hiller UH-12A](https://openairdocs.org/model/hiller-uh-12a) (registry code 4360104) (OpenAirDocs)
- Registry engine: [Franklin 6V-335 series](https://openairdocs.org/engine/franklin-6v-335-series) (registry code 27039, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 178
- Year built: 1950
- Airframe hours: 2850
- Engines: FRANKLIN 6V-335 SERIES 200 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Rotor Wing Nuts LLC
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 20, 2022
- Airport: GPH, Midwest National Air Center Airport, runway 18/36, 5,502 × 100 ft, asphalt
- Equipment: ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 69; injuries: none; private; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: basicmed, with waivers/limitations; last flight review May 5, 2023; seat: center; restraint: lap only; flight hours: 509 total, 21.8 in this make and model, 242.8 as pilot in command, 23.5 in the last 90 days, 0.7 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: 2,100 ft broken
- Temperature: 77 °F, dew point 55 °F
- Altimeter: 30.01 inHg
- Observed at: KGPH
- METAR: KGPH 272315Z AUTO 04007KT 10SM SCT047 SCT055 25/13 A3001 RMK AO2

## 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 20230827019679A](https://openairdocs.org/incident/20230827019679A), Aug 27, 2023: Hiller UH-12A, Mosby, MO, Substantial damage. The pilot was unable to maintain altitude during hover taxi and the tail boom struck the ground.

## Other investigations on N8178H (1)

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.

- [NTSB SEA71FYC42](https://openairdocs.org/ntsb/SEA71FYC42), Jun 11, 1971: Hiller UH12A (N8178H), Brooks, OR, destroyed, 1 fatal

## Docket (2 files)

The files NTSB released with the investigation on March 21, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192949. 2.5 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 534 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16716388&FileExtension=pdf&FileName=NTSB%206120%201%20Form_Redacted-Rel.pdf
- Photo array (item 2, PDF, 4 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16717173&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf

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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