# NTSB DEN85LA052: Cessna 172, N9033H, Ft. Collins, CO, December 30, 1984

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: December 30, 1984, 07:35 local (14:35 UTC)
- Place: Ft. Collins, CO
- Location: 40.5853° N, 105.0844° W: Placed by OpenAirDocs: center of Fort Collins, CO, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=40.5853&lon=-105.0844&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16617
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85LA052
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16617/pdf
- Page: https://openairdocs.org/ntsb/DEN85LA052

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - engine assembly,crankshaft - inoperative (cause)
- Forced landing, descent - emergency
- Hard landing, landing - flare/touchdown
  - terrain condition - rough/uneven

## Analysis

THE PLT REPORTED THAT UPON ARRIVAL AT FORT COLLINS, AND WHILE AT CRUISE ALTITUDE, THE ENG SUDDENLY LOST POWER. DURING THE EMERGENCY DESCENT MANEUVERING HE LOST SIGHT OF THE AIRPORT AND LANDED IN A PLOWED FIELD. POST CRASH EXAMINATION OF ENG REVEALED THE CRANKSHAFT ACCESSORY DRIVE GEAR INDEPENDENTLY ROTATED FROM THE CRANKSHAFT. THE RETAINING DOWEL, P/N STD-1065, WAS FOUND SHEARED. THE RETAINING BOLT WAS BACKED OUT 5 OR 6 TURNS. THE SAFETY CLIP WAS IN PLACE AND FUNCTIONAL, BUT NOT ENGAGED.

## Aircraft

- Registration: N9033H (not matched to a registry record)
- Reported make and model: CESSNA 172
- Category: Airplane
- Serial number: 17265909
- Airframe hours: 3584
- Engines: LYCOMING O-360-E20 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Charles Beck
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, September 29, 1983
- Departed: APA, ENGLEWOOD, CO
- Destination: 3V5, FORT COLLINS, CO
- Flight plan: VFR
- Airport: 3V5, Downtown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 146 total, 29 in this make and model, 65 as pilot in command, 6 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 45 °F, dew point 16 °F
- Altimeter: 30.00 inHg

## 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 19841230069009A](https://openairdocs.org/incident/19841230069009A), Dec 30, 1984: Cessna 172M, Ft Collins, CO, Substantial damage. Accessory drive gear retaining dowel sheared. Gear operates mags and valves. Engine quit, landed, nosed onto back.

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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