# NTSB SEA93LA105: Kaman HH-43F, N846D, Anatone, WA, May 12, 1993

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Limited investigation · Final report
- Date: May 12, 1993, 07:15 local (14:15 UTC)
- Place: Anatone, WA
- Coordinates: 46.079105, -117.26947 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.0791&lon=-117.2695&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report June 22, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 43019
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA93LA105
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43019/pdf
- Page: https://openairdocs.org/ntsb/SEA93LA105

## Probable cause

FATIGUE FAILURE OF THE ROTOR TRANSMISSION DRIVE SYSTEM, RESULTING FROM THE IMPROPER CERTIFICATION/APPROVAL OF THE AIRCRAFT MODIFICATION BY THE FEDERAL AVIATION ADMINISTRATION.

## Sequence of events

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

- Airframe/component/system failure/malfunction, hover
  - rotor drive system,main gearbox/transmission - fatigue (cause)
  - inadequate certification/approval, faa(organization) (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE CONVERTED MILITARY HELICOPTER WAS IN A HOVER LIFTING AN EXTERNAL LOAD OF LOGS WHEN THE MAIN ROTOR PYLONS SEPARATED IN FLIGHT, RESULTING IN AN UNCONTROLLED INVERTED DESCENT INTO THE GROUND. ON-SCENE EXAMINATION REVEALED THAT THE TRANSMISSION ROTOR INPUT GEAR SHAFT, P/N K774515-5F, HAD FRACTURED. SAFETY BOARD METALLURGICAL EXAMINATION SHOWED THAT THE FRACTURE WAS CHARACTERISTIC OF FATIGUE FAILURE, AND INDICATED REPETITIVE HIGH LOADS. THE FAA TYPE-CERTIFICATE, BASED ON MILITARY CONFIGURATION, LISTS THE APPROVED ENGINE AS 1100 SHP, AND THE EXTERNAL LOAD LIMIT AS 2,300 LBS. THE FAA HAD APPROVED INSTALLATION OF A 1400 SHP ENGINE, AND OPERATIONS WITH AN INCREASED EXTERNAL LOAD LIMIT OF 4,000 LBS.

## Aircraft

- Registration: [N846D](https://openairdocs.org/deregistered/N846D-1995-12-01), registration cancelled 1995-12-01, S/N 581846 (OpenAirDocs)
- Reported make and model: KAMAN HH-43F
- Registry model: [Kaman HH-43F](https://openairdocs.org/model/kaman-hh-43f) (registry code 4800708) (OpenAirDocs)
- Category: Helicopter
- Serial number: 58-1846
- Airframe hours: 7266
- Engines: LYCOMING T53-L-13B 1400 horsepower turbo shaft
- Damage: Destroyed
- Fire: On-Ground
- Flight: Other work use, Part 133
- Operator: Woody Contracting, Inc
- Registered owner: Robert & Sharon Woody
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, April 27, 1993, 42 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; commercial, flight instructor; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 18,970 total, 3,051 in this make and model, 18,051 as pilot in command, 344 in the last 90 days, 113 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 130° at 8 knots
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 64 °F, dew point 46 °F
- Altimeter: 29.00 inHg
- Observed at: LWS, 26 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 19930512013379A](https://openairdocs.org/incident/19930512013379A), May 12, 1993: Kaman HH43F, Anatone, WA, Destroyed, 1 fatal. Main rotor drive shaft failed during external load lift. Rotor assembly separated. Load was 800 lbs over load limit

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.