# NTSB DEN72AD025: Beech 99A, N21FW, Greeley, CO, November 24, 1971

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Closed
- Date: November 24, 1971
- Place: Greeley, CO · GREELEY, CO
- Location: 40.4233° N, 104.7091° W: Placed by OpenAirDocs: center of Greeley, CO, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=40.4233&lon=-104.7091&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 8 uninjured
- Status: Completed, report June 27, 1972
- Report: Brief approved by the director
- Safety recommendations: Yes
- NTSB case key (mKey): 79398
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN72AD025
- Page: https://openairdocs.org/ntsb/DEN72AD025

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
1-0026  71/11/24 NR.GREELEY,COLO       BEECH 99A           CR-  0  0  2  SCHED DOM PASSG SRV       AIRLINE TRANSPORT, AGE
        TIME - 1912                    N21FW               PX-  0  0  6                            41, 16236 TOTAL HOURS,
                                       DAMAGE-SUBSTANTIAL  OT-  0  0  0                            125 IN TYPE, INSTRUMENT
                                                                                                   RATED.
        OPERATOR - FRONTIER AIRLINES,INC.
        DEPARTURE POINT             INTENDED DESTINATION
          CHEYENNE,WYO                DENVER,COLO
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           PROPELLER/ROTOR FAILURE: PROPELLER                       IN FLIGHT: DESCENDING
           ENGINE TEARAWAY                                          IN FLIGHT: DESCENDING
        PROBABLE CAUSE(S)
           POWERPLANT - PROPELLER AND ACCESSORIES: BLADES
           MISCELLANEOUS ACTS,CONDITIONS - FATIGUE FRACTURE
           MISCELLANEOUS ACTS,CONDITIONS - OVERLOAD FAILURE
           PERSONNEL - PRODUCTION-DESIGN-PERSONNEL: OTHER
        FACTOR(S)
           MISCELLANEOUS ACTS,CONDITIONS - SEPARATION IN FLIGHT
           MISCELLANEOUS ACTS,CONDITIONS - VIBRATION,EXCESSIVE
        EMERGENCY CIRCUMSTANCES - PRECAUTIONARY LANDING ON AIRPORT
                                  SUSPECTED OR KNOWN AIRCRAFT DAMAGE
        REMARKS- R PROP BLADE FAILED DUE FATIGUE INDUCED BY IMPROPER MACHINING IN BALANCE HOLE CAVITY,DMGD FUSELAGE
```

## Aircraft

- Registration: [N21FW](https://openairdocs.org/aircraft/N21FW), registered now, S/N U-117, built 1969 (OpenAirDocs)
- Reported make and model: BEECH 99A
- Registry model: [Beech B-99](https://openairdocs.org/model/beech-b-99) (registry code 1154004) (OpenAirDocs)
- Registry engine: [U/A Canada PT6 SER 578HP](https://openairdocs.org/engine/u-a-canada-pt6-ser-578hp) (registry code 61501, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Engines: turbo prop
- Damage: Substantial damage

## Other investigations on N21FW (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 SEA72AS032](https://openairdocs.org/ntsb/SEA72AS032), Feb 18, 1972: Beech 99 (N21FW), Spokane, WA, 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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