# NTSB OAK70D0153: Hiller Acft UH-12L, N9730C, Mammoth Lks, CA, September 4, 1969

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Closed
- Date: September 4, 1969
- Place: Mammoth Lks, CA · MAMMOTH LKS, CA
- Location: 37.6244° N, 118.9884° W: Placed by OpenAirDocs: center of Mammoth Lakes, CA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=37.6244&lon=-118.9884&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 2 minor
- Status: Completed, report May 18, 1970
- Report: Brief approved by the director
- NTSB case key (mKey): 152517
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=OAK70D0153
- Page: https://openairdocs.org/ntsb/OAK70D0153

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
3-4192   69/9/4    MAMMOTH LKS,CALIF   HILLER ACFT UH-12L  CR-  0  0  1  MISCELLANEOUS             COMMERCIAL, AGE 34, 3200
        TIME - 1450                    N9730C              PX-  0  0  1  SEARCH AND RESCUE         TOTAL HOURS, 100 IN TYPE,
                                       DAMAGE-SUBSTANTIAL  OT-  0  0  0                            NOT INSTRUMENT RATED.
        DEPARTURE POINT             INTENDED DESTINATION
          MAMMOTH LKS,CALIF           LAKE EDIZA,CALIF
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           ENGINE FAILURE OR MALFUNCTION                            IN FLIGHT: NORMAL CRUISE
           ROLL OVER                                                LANDING: POWER-ON LANDING
        PROBABLE CAUSE(S)
           POWERPLANT - EXHAUST SYSTEM: EXTERNAL SUPERCHARGER
           MISCELLANEOUS ACTS,CONDITIONS - STUCK
           TERRAIN - ROUGH/UNEVEN
        PARTIAL POWER LOSS - PARTIAL LOSS OF POWER - 1 ENGINE
        EMERGENCY CIRCUMSTANCES - FORCED LANDING OFF AIRPORT ON LAND
        REMARKS- BELLOWS STUCK IN DENSITY CONTROLLER.
```

## Aircraft

- Registration: [N9730C](https://openairdocs.org/deregistered/N9730C-1981-10-16), registration cancelled 1981-10-16, S/N 2512 (OpenAirDocs)
- Reported make and model: HILLER ACFT UH-12L
- Registry model: [Hiller UH-12L4](https://openairdocs.org/model/hiller-uh-12l4) (registry code 4360128) (OpenAirDocs)
- Category: Helicopter
- Engines: reciprocating
- Damage: 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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