# NTSB DEN90LA098: Cessna 310B, N6641B, Elizabeth, CO, April 21, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 21, 1990, 17:00 local (23:00 UTC)
- Place: Elizabeth, CO
- Coordinates: 39.359973, -104.600952 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.3600&lon=-104.6010&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report September 28, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17923
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90LA098
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17923/pdf
- Page: https://openairdocs.org/ntsb/DEN90LA098

## Probable cause

THE PILOT'S ATTEMPT TO TAKEOFF WITH A KNOWN DEFICIENCY AND THE PARTIAL FAILURE OF THE PROPELLER FEATHERING SYSTEM.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - propeller system/accessories,feathering system - failure,partial
  - precautionary landing - performed, pilot in command(cfi)
- Airframe/component/system failure/malfunction, takeoff - initial climb
  - propeller system/accessories,feathering system - failure,partial (cause)
  - operation with known deficiencies in equipment - attempted, pilot in command (cause)
  - propeller system/accessories,dome - cracked
- Loss of control - in flight, takeoff - initial climb
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - open field
  - terrain condition - rough/uneven

## Analysis

THE COMMERCIAL, (CFI), PILOT WAS PERFORMING A TRAINING FLIGHT. DURING SINGLE ENGINE TRAINING, THE LEFT PROPELLER BEGAN AN UNCOMMANDED RETURN TO FLAT PITCH. THE CFI TOOK THE CONTROLS, MADE A PRECAUTIONARY LANDING, AND INSPECTED THE PROPELLER. AFTER AN EXTENSIVE RUNUP, THE CFI ELECTED TO ATTEMPT A TKAEOFF FROM A NEARBY DIRT ROAD. DURING INITIAL CLIMB, AT 20 FEET AGL, THE LEFT PROPELLER WENT INTO FLAT PITCH, CAUSED THE PLANE TO YAW TO THE LEFT, THE LEFT WING DROPPED AND THE PLANE LANDED HARD, WITH THE GEAR RETRACTED. THE LANDING GEAR, BOTH WINGS, AND THE GUSELAGE WERE BENT AND TWISTED. THE LEFT PROPELLER DOME SHOWED EVIDENCE OF OIL LEAKAGE OVER A PERIOD OF TIME. THE LEFT ENGINE CONTAINED 3 QUARTS OF OIL, WHICH WAS BELOW THE MINIMUM LEVEL. ONE PROPELLER BLADE ON THE LEFT ENGINE HAD A BROKEN PITCH CHANGE LINK. THE DOME WAS EXTENSIVELY CRACKED AND HAD BEGUN TO DISINTEGRATE.

## Aircraft

- Registration: [N6641B](https://openairdocs.org/deregistered/N6641B-2015-05-04), registration cancelled 2015-05-04, S/N 35741, built 1958 (OpenAirDocs)
- Reported make and model: CESSNA 310B
- Registry model: [Cessna 310B](https://openairdocs.org/model/cessna-310b) (registry code 2074208) (OpenAirDocs)
- Registry engine: [Continental O-470 series](https://openairdocs.org/engine/continental-o-470-series) (registry code 17026, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 35741
- Airframe hours: 4625
- Engines: CONTINENTAL O-470-M 240 horsepower reciprocating
- Damage: Substantial damage
- Fire: Unknown
- Flight: Instructional, Part 91
- Operator: Preferred Avitation, Ltd.
- Last inspection: 100 hour, October 25, 1989, 77 hours before
- Departed: APA, DENVER, CO
- Destination: APA
- Airport: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 49; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 2,600 total, 96 in this make and model, 2,582 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 50 statute miles
- Lowest ceiling: 5,000 ft broken
- Temperature: -0 °F, dew point -0 °F

## Other investigations on N6641B (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 LAX74FUA06](https://openairdocs.org/ntsb/LAX74FUA06), Aug 31, 1973: Cessna 310B (N6641B), Torrance, CA, minor damage, 1 fatal

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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