# NTSB DEN92IA014: Cessna 172RG, N9320D, Broomfield, CO, December 5, 1991

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: December 5, 1991, 16:45 local (23:45 UTC)
- Place: Broomfield, CO
- Coordinates: 39.940361, -105.059677 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.9404&lon=-105.0597&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18167
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN92IA014
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18167/pdf
- Page: https://openairdocs.org/ntsb/DEN92IA014

## Probable cause

FAILURE OF THE LEFT MAIN LANDING GEAR PIVOT ASSEMBLY DUE TO DUCTILE TORSIONAL OVERSTRESS.

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - vfr pattern - final approach
  - landing gear,normal retraction/extension assembly - failure,total (cause)
  - landing gear,normal retraction/extension assembly - overload (cause)
- In flight collision with terrain/water, landing - flare/touchdown
  - terrain condition - runway
  - gear down and locked - not possible
  - wheels up landing - intentional, pilot in command

## Analysis

UPON RETURN FROM A LOCAL AREA INSTRUCTIONAL FLIGHT, THE LEFT MAIN LANDING GEAR FAILED TO EXTEND.  AFTER REPEATED UNSUCCESSFUL ATTEMPTS TO EXTEND AND LOCK THE LEFT MAIN LANDING GEAR, THE PILOT MADE AN INTENTIONAL WHEELS UP LANDING. POST INCIDENT EXAMINATION DISCLOSED THE LANDING GEAR PIVOT ASSEMBLY FAILED IN DUCTILE TORSIONAL OVERSTRESS.  THERE WAS NO EVIDENCE OF FATIGUE OR PREEXISTING CRACKS.

## Aircraft

- Registration: [N9320D](https://openairdocs.org/aircraft/N9320D), registered now, S/N 172RG1119, built 1982 (OpenAirDocs)
- Reported make and model: CESSNA 172RG
- Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (OpenAirDocs)
- Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs)
- Category: Airplane
- Serial number: 172RG1119
- Airframe hours: 4458
- Engines: LYCOMING O-360-F1A6 180 horsepower reciprocating
- Damage: Minor damage
- Flight: Instructional, Part 91
- Operator: Airwest Flying Club
- Registered owner: Keigth A. Franz
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, October 4, 1991, 76 hours before
- Airport: BJC, Jefferson County, runway 29, 9,000 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 29; 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: 510 total, 85 in this make and model, 430 as pilot in command, 52 in the last 90 days, 24 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 8 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 41 °F, dew point 25 °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).

- [Incident 19911205058509I](https://openairdocs.org/incident/19911205058509I), Dec 5, 1991: Cessna 172RG, Denver, CO, Minor damage. Pilot was unable to lower landing gear. Landed gear up. Pivot shaft in left main gear actuator sheared.

## Other investigations on N9320D (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 DEN01LA164](https://openairdocs.org/ntsb/DEN01LA164), Sep 27, 2001: Cessna 172RG (N9320D), Englewood, CO, substantial damage. Probable cause: the failure of the dual student to verify that the landing gear was down and locked, and the failure of the flight instructor to adequately supervise the dual student.

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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