# NTSB CHI71FEE90: Bell 47G-4A, N4033G, Chicago, IL, June 28, 1971

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Closed
- Date: June 28, 1971
- Place: Chicago, IL · CHICAGO, IL
- Location: 41.8500° N, 87.6501° W: Placed by OpenAirDocs: center of Chicago, IL, within about 9 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.8500&lon=-87.6501&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 29, 1971
- Report: Brief approved by the director
- NTSB case key (mKey): 161157
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI71FEE90
- Page: https://openairdocs.org/ntsb/CHI71FEE90

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
3-0505  71/6/28    CHICAGO,ILL         BELL 47G-4A         CR-  0  0  1  MISCELLANEOUS             COMMERCIAL, AGE 41, 644
        TIME - 0940                    N4033G              PX-  0  0  1  POLICE PATROL             TOTAL HOURS, ALL IN TYPE,
                                       DAMAGE-SUBSTANTIAL  OT-  0  0  0                            NOT INSTRUMENT RATED.
        DEPARTURE POINT             INTENDED DESTINATION
          MIDWAY ARPT,ILL             LOCAL
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           ENGINE FAILURE OR MALFUNCTION                            IN FLIGHT: NORMAL CRUISE
           HARD LANDING                                             LANDING: POWER-OFF AUTOROTATIVE LANDING
        PROBABLE CAUSE(S)
           POWERPLANT - ENGINE STRUCTURE: VALVE ASSEMBLIES
           MISCELLANEOUS ACTS,CONDITIONS - STICKING
           PILOT IN COMMAND - MISJUDGED SPEED AND ALTITUDE
        FACTOR(S)
           TERRAIN - OTHER
        PARTIAL POWER LOSS - PARTIAL LOSS OF POWER - 1 ENGINE
        EMERGENCY CIRCUMSTANCES - FORCED LANDING OFF AIRPORT ON LAND
        REMARKS- EX VALVE NR 6 CYL STICKING,SET TO MFG SPECS.LYCOMING ENGINEERING CHANGE ISSUED 6/30/71 COVERS.
```

## Aircraft

- Registration: [N4033G](https://openairdocs.org/deregistered/N4033G-1982-03-26), registration cancelled 1982-03-26, S/N 7620, built 1968 (OpenAirDocs)
- Reported make and model: BELL 47G-4A
- Registry model: [Bell 47G-4A](https://openairdocs.org/model/bell-47g-4a) (registry code 1181031) (OpenAirDocs)
- Category: Helicopter
- Engines: reciprocating
- Damage: Substantial damage

## Other investigations on N4033G (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 CHI72FEE28](https://openairdocs.org/ntsb/CHI72FEE28), Sep 22, 1971: Bell 47G-4A (N4033G), Chicago, IL, substantial damage

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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