# NTSB DEN93LA068: Cessna 172N, N4829E, Livermore, CO, June 11, 1993

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 10, 1993, 19:20 local (Jun 11, 1993, 01:20 UTC)
- Place: Livermore, CO
- Coordinates: 40.869796, -105.369697 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.8698&lon=-105.3697&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report November 19, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18295
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN93LA068
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18295/pdf
- Page: https://openairdocs.org/ntsb/DEN93LA068

## Probable cause

A PARTIAL POWER LOSS WHEN THE ROCKER BOX FOR ONE CYLINDER DISENGAGED.  A FACTOR WAS:  UNSUITABLE TERRAIN FOR A FORCED LANDING.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, cruise - normal
  - engine assembly,rocker arm/tappet - disengaged (cause)
- Forced landing, descent - emergency
  - terrain condition - none suitable (contributing factor)
- On ground/water collision with object, landing - roll
  - object - fence post

## Analysis

WHILE ON A LOCAL AREA PERSONAL FLIGHT, THE ENGINE RPM DROPPED FROM 2,300 TO 1,400 RPM FOLLOWED BY ENGINE VIBRATION. THE PILOT ELECTED TO LAND ON THE ONLY ROAD IN THE AREA WHICH CONTAINED A 40 DEGREE RIGHT TURN ALONG THE LANDING ROLL PATH.  AS THE AIRCRAFT NEGOTIATED THE TURN, THE RIGHT WING STRUCK A FENCE POST AND THE AIRCRAFT SPUN INTO A DITCH. EXAMINATION REVEALED A FAILURE OF THE RIGHT FORWARD CYLINDER VALVE ROCKER BOX EXHAUST STUD WHICH BACKED OUT AND PREVENTED THE INTAKE VALVE FROM WORKING PROPERLY.

## Aircraft

- Registration: [N4829E](https://openairdocs.org/deregistered/N4829E-1996-03-02), registration cancelled 1996-03-02, S/N 17271668 (OpenAirDocs)
- Reported make and model: CESSNA 172N
- Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs)
- Category: Airplane
- Serial number: 17271668
- Airframe hours: 3925
- Engines: LYCOMING O-320-H2AD 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Northern Colorado Air Charter, doing business as Ncac
- Registered owner: Northern Colorado Air Charter
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 5, 1993, 60 hours before
- Departed: 3V5, FT.COLLINS, CO
- Destination: 3V5
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; military, private, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 1,645 total, 23 in this make and model, 24 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 110° at 8 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 73 °F, dew point 37 °F
- Altimeter: 30.00 inHg
- Observed at: FNL, 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 19930610022869A](https://openairdocs.org/incident/19930610022869A), Jun 10, 1993: Cessna 172N, Livermore, CO, Substantial damage. Lost power. Wing struck post while landing on a road. Rocker box stud backed out. Inop exhaust valve bent push rod.

## Other investigations on N4829E (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 FTW94FA034](https://openairdocs.org/ntsb/FTW94FA034), Nov 15, 1993: Cessna 172N (N4829E), Fort Collins, CO, destroyed. Probable cause: POWER LOSS DUE TO THROTTLE LINKAGE DISCONNECT. FACTORS WERE MISSING COTTER KEY, IMPROPER MAINTENANCE, AND THE LACK OF SUITABLE TERRAIN FOR THE FORCED LANDING.

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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