# NTSB OAK70D0121: Mooney M-20C, N6704U, Arroyo, CA, August 15, 1969

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Closed
- Date: August 15, 1969
- Place: Arroyo, CA · ARROYO, CA
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 4 uninjured
- Status: Completed, report December 23, 1969
- Report: Brief approved by the director
- NTSB case key (mKey): 165143
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=OAK70D0121
- Page: https://openairdocs.org/ntsb/OAK70D0121

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
3-2689  69/8/15    ARROYO,CALIF        MOONEY M-20C        CR-  0  0  1  NONCOMMERCIAL             PRIVATE, AGE 47, 170
        TIME - 1530                    N6704U              PX-  0  0  3  PLEASURE/PERSONAL TRANSP  TOTAL HOURS, 150 IN TYPE,
                                       DAMAGE-DESTROYED    OT-  0  0  0                            NOT INSTRUMENT RATED.
        DEPARTURE POINT             INTENDED DESTINATION
          SANTA MONICA,CALIF          MONTEREY,CALIF
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           PROPELLER/ROTOR FAILURE: PROPELLER                       IN FLIGHT: NORMAL CRUISE
           GEAR COLLAPSED                                           LANDING: LEVEL OFF/TOUCHDOWN
        PROBABLE CAUSE(S)
           PERSONNEL - MAINTENANCE,SERVICING,INSPECTION: INADEQUATE MAINTENANCE AND INSPECTION
           POWERPLANT - PROPELLER AND ACCESSORIES: HUBS
           MISCELLANEOUS ACTS,CONDITIONS - MATERIAL FAILURE
           AIRFRAME - LANDING GEAR: NOSEWHEEL ASSEMBLIES
           TERRAIN - ROUGH/UNEVEN
        FACTOR(S)
           MISCELLANEOUS ACTS,CONDITIONS - OVERLOAD FAILURE
        EMERGENCY CIRCUMSTANCES - FORCED LANDING OFF AIRPORT ON LAND
                                  PROP/ENGINE VIBRATION
        REMARKS- BLADE RETAINING THREAD AREA IN HUB BARREL FAILED ALLOWING PROP BLADE TO BECOME DETACHED.
```

## Aircraft

- Registration: [N6704U](https://openairdocs.org/deregistered/N6704U-2018-01-05), registration cancelled 2018-01-05, S/N 2436, built 1963 (OpenAirDocs)
- Reported make and model: MOONEY M-20C
- Registry model: [Mooney M20C](https://openairdocs.org/model/mooney-m20c) (registry code 5870208) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Airplane
- Engines: reciprocating
- Damage: Destroyed

## Other investigations on N6704U (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 WPR14FA188](https://openairdocs.org/ntsb/WPR14FA188), May 6, 2014: Mooney M20C (N6704U), Cody, WY, substantial damage, 2 fatal. Probable cause: The non-instrument rated pilots’ decision to continue flight into known instrument meteorological conditions over mountainous terrain, which resulted in controlled flight into terrain.

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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