# NTSB CHI91IA120: Cessna 172RG, N9592B, West Chicago, IL, April 2, 1991

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: April 2, 1991, 16:00 local (21:00 UTC)
- Place: West Chicago, IL
- Coordinates: 41.879085, -88.219779 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.8791&lon=-88.2198&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report May 28, 1993
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 14928
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91IA120
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14928/pdf
- Page: https://openairdocs.org/ntsb/CHI91IA120

## Probable cause

FAILURE OF THE SPLINED SHAFT ON THE RIGHT MAIN LANDING GEAR PIVOT ASSEMBLY.  A FACTOR RELATED TO THE INCIDENT WAS INADEQUATE DESIGN OF THE LANDING GEAR PIVOT ASSEMBLY.

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering
  - landing gear,normal retraction/extension assembly - fractured (cause)
  - gear extension - not possible
  - acft/equip,inadequate design, production/design personnel (contributing factor)
- Gear not extended, landing
  - wheels up landing - intentional, pilot in command(cfi)

## Analysis

AFTER REPEATED ATTEMPTS TO LOWER THE LANDING GEAR, ONLY THE LEFT MAIN AND NOSE GEAR WOULD EXTEND.  THE PILOTS ELECTED TO MAKE A WHEELS-UP LANDING.  DURING THE LANDING, THE LOWER FUSELAGE AND PROPELLER TIPS RECEIVED MINOR DAMAGE.  AN INVESTIGATION REVEALED THE RIGHT MAIN LANDING GEAR PIVOT ASSEMBLY (PN 2441100-1) HAD FAILED.  A METALLURGICAL EXAMINATION DISCLOSED THE SPLINED SHAFT ON THE PIVOT ASSEMBLY HAD FRACTURED IN TORSIONAL OVERLOAD.  AS A RESULT, MECHANICAL EXTENSION OF THE RIGHT MAIN LANDING GEAR WAS NOT POSSIBLE.

## Aircraft

- Registration: [N9592B](https://openairdocs.org/deregistered/N9592B-2015-05-21), registration cancelled 2015-05-21, S/N 172RG0905, built 1981 (OpenAirDocs)
- Reported make and model: CESSNA 172RG
- Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 172RG0905
- Airframe hours: 4567
- Engines: LYCOMING O-360-F1A6 180 horsepower reciprocating
- Damage: Minor damage
- Flight: Instructional, Part 91
- Operator: Av. Training Enterprise Of Il.
- Registered owner: Av. Training Enterprise Of Il.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, March 20, 1991, 45 hours before
- Airport: DPA, Dupage, runway 15, 3,400 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; flight instructor, commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 1,531 total, 280 in this make and model, 1,430 as pilot in command, 25 in the last 90 days, 15 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 140° at 10 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 54 °F, dew point 45 °F
- Altimeter: 30.00 inHg
- Observed at: DPA, 1 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).

- [Incident 19910402015659I](https://openairdocs.org/incident/19910402015659I), Apr 2, 1991: Cessna 172RG, Chicago/West Ch, IL, Minor damage. Unable to lower landing gear and landed gear up. Found right hand landing gear pivot assembly had sheared off.

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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