# NTSB CEN20CA334: Hughes 369, N104SU, Delia, KS, August 5, 2020

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 4 · Data collection · Final report
- Date: August 5, 2020, 17:45 local (22:45 UTC)
- Place: Delia, KS
- Coordinates: 39.259998, -95.988609
- Nearby events: https://openairdocs.org/map.md?lat=39.2600&lon=-95.9886&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-low-alt flying: Miscellaneous/other](https://openairdocs.org/ntsb-events/900)
- 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
- NTSB case key (mKey): 101782
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20CA334
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101782/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101782
- Page: https://openairdocs.org/ntsb/CEN20CA334

## Probable cause

Foreign object damage sustained to the main rotor blades due to aerial tree trimming.

## Findings

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

- [Main rotor system: main rotor blade system](https://openairdocs.org/ntsb-findings/01046210): Aircraft › Aircraft propeller/rotor · Damaged/degraded (probable cause); cases with it: [Hughes Helicopters HUGHES 369D, 6 cases](https://openairdocs.org/ntsb-findings/01046210/cases.md?model=4470706), [All aircraft, 60 cases](https://openairdocs.org/ntsb-findings/01046210/cases.md)
- [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Hughes Helicopters HUGHES 369D, 4 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=4470706), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md)

## Sequence of events

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

- [Maneuvering-low-alt flying: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Hughes Helicopters HUGHES 369D, 9 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=4470706), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md)

## Analysis

While conducting an aerial tree-trimming flight with an external load aerial saw, the pilot heard a loud “thump” and felt a collision. A heavy vibration was felt, and the pilot landed in a nearby cornfield without further incident. Upon landing substantial damage was found to the main rotor blades with embedded pieces of tree bark and vegetation found in the blades. The pilot reported that there were no mechanical malfunctions that contributed to the accident. The aerial saw was suspended about 120 ft below the helicopter. The operator noted that this distance is normally adequate to prevent foreign object damage (FOD) to the main rotor blades.

## Aircraft

- Registration: [N104SU](https://openairdocs.org/aircraft/N104SU), registered now, S/N 670151D, built 1977 (OpenAirDocs)
- Reported make and model: HUGHES 369 (D)
- Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs)
- Registry engine: [Rolls-Royce 250-C20B](https://openairdocs.org/engine/rolls-royce-250-c20b) (registry code 54385, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 670151D
- Year built: 1977
- Airframe hours: 9856.3
- Engines: Rolls-Royce 250-C20B 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: External load, Part 133
- Operator: Signature Utility, doing business as Signature Utility Services LLC
- Registered owner: Signature Utility
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, July 9, 2020, 34.9 hours before
- Departed: Delia, KS
- Destination: Delia, KS
- Equipment: Electronic flight bag or handheld device, ADS-B, Satellite tracking device, Handheld GPS, Onboard weather

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; injuries: none; private, commercial; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review January 10, 2019; seat: left; restraint: 3-point; flight hours: 5,260 total, 3,230 in this make and model, 5,160 as pilot in command, 75 in the last 90 days, 30 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 120° at 8 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 59 °F
- Altimeter: 29.98 inHg
- Observed at: KTOP, 20 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 20200805009889A](https://openairdocs.org/incident/20200805009889A), Aug 5, 2020: Hughes 369D, Delia, KS, Substantial damage. On 08/05/2020, at 1745 CDT, a Hughes 369D, N104SU, registered to [privacy data omitted], (5U2L) was conducting airborne vegetation management by sawing trees…

## Docket (2 files)

The files NTSB released with the investigation on July 29, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101782. 3.0 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 12 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11509711&FileExtension=pdf&FileName=NTSB%20Form%206120%20ca334_Redacted-Rel.pdf
- Photo array (item 2, PDF, 1 page, 1 photo, 236 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11510224&FileExtension=pdf&FileName=Docket%20Photo-Array%20CEN20CA334-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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