# NTSB MKC85FA182: Ronald Houk RD-1, N4741A, St. Charles, MO, August 13, 1985

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: August 12, 1985, 19:30 local (Aug 13, 1985, 00:30 UTC)
- Place: St. Charles, MO
- Coordinates: 38.790737, -90.510978 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.7907&lon=-90.5110&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 33851
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MKC85FA182
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/33851/pdf
- Page: https://openairdocs.org/ntsb/MKC85FA182

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - lubricating system - failure,partial (cause)
  - lubricating system,oil cooler - separation
  - propeller system/accessories,blade - overload
  - engine assembly,other - vibration
  - vertical stabilizer surface - overload
  - rotor system,main rotor blade - overload
- Loss of control - in flight, cruise
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE HOME BUILT GYROCOPTER WAS BEING FLOWN BY THE OWNER/BUILDER/DESIGNER WHO HAD AN AIRPLANE, SINGLE-ENG, LAND RATING. SHORTLY AFTER THE GYROCOPTER TOOK OFF, THE ENG WAS OPERATING AT A HIGH RPM WHEN A WITNESS HEARD A POP/NOISE. SUBSEQUENTLY, THE GYROCOPTER CRASHED IN A CORN FIELD ABOUT 1-1/2 MI FROM THE DEPARTURE POINT. THE MAIN WRECKAGE WAS FOUND INVERTED. ONE ROTOR BLADE, THE OIL COOLER & THE LEFT VERTICAL STABILIZER & RUDDER WERE FOUND 60 TO 150 FT FROM THE MAIN WRECKAGE. BOTH OF THE WOODEN PROP BLADES HAD SHATTERED. THE OIL COOLER HAD BEEN INSTALLED BELOW THE ENG & JUST FORWARD OF THE PROP. ITS UPPER SIDE HAD BEEN ATTACHED WITH A SINGLE SOLID MOUNT USING AN 'L' SHAPED ALUMINUM STRAP. ITS LOWER SIDE WAS FASTENED WITH A SEMIFLEXIBLE MOUNTING. THERE WAS EVIDENCE THAT THE UPPER MOUNT HAD FAILED & ALLOWED THE OIL COOLER TO MOVE AFT INTO THE PLANE OF ROTATION OF THE PROP BLADES. EXCEPT FOR THE OIL COOLER BRACKET, NO PRE- ACCIDENT MECHANICAL PROBLEMS WERE FOUND.

## Aircraft

- Registration: N4741A (not matched to a registry record)
- Reported make and model: RONALD HOUK RD-1
- Category: Gyroplane, amateur-built
- Serial number: 100
- Airframe hours: 2
- Engines: LYCOMING O-290-G 125 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: Ronald D. Houk
- Airworthiness certificate: Special, Experimental (Special)
- Airport: 3SL, St Charles City, runway 36, 3,800 × 75 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 27; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: front; toxicology performed; flight hours: 52 total, 2 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 160° at 13 knots
- Visibility: 4 statute miles
- Lowest ceiling: none
- Temperature: 90 °F, dew point 75 °F
- Altimeter: 29.00 inHg
- Observed at: STL, 12 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 19850812049819A](https://openairdocs.org/incident/19850812049819A), Aug 12, 1985: Amtrrd RD1, St Charles, MO, Destroyed. Oil cooler upper attachment bracket broke. Propeller blades struck cooler and uncontrollable impact resulted.

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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