# NTSB SEA65A0065: Brantly B-2, N5901X, Martha Lake, WA, May 31, 1965

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Closed
- Date: May 31, 1965
- Place: Martha Lake, WA · MARTHA LAKE, WA
- Location: 47.8447° N, 122.2331° W: Placed by OpenAirDocs: center of Martha Lake, WA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=47.8447&lon=-122.2331&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report October 4, 1965
- Report: Brief approved by the director
- NTSB case key (mKey): 178207
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA65A0065
- Page: https://openairdocs.org/ntsb/SEA65A0065

## NTSB brief

```
----------------------------------------------------------------------------------------------------------------------------
 FILE    DATE          LOCATION          AIRCRAFT DATA       INJURIES       FLIGHT                        PILOT DATA
                                                               F  S M/N     PURPOSE
----------------------------------------------------------------------------------------------------------------------------
2-0511  65/5/31    MARTHA LAKE WASH    BRANTLY B-2         CR-  0  0  2  INSTRUCTIONAL             COMMERCIAL, FL.INSTR.,
        TIME - 1200                    N5901X              PX-  0  0  0  DUAL                      AGE 36, 400 TOTAL HOURS,
                                       DAMAGE-SUBSTANTIAL  OT-  0  0  0                            150 IN TYPE, NOT
                                                                                                   INSTRUMENT RATED.
        NAME OF AIRPORT - MARTHA LAKE
        TYPE OF ACCIDENT                                         PHASE OF OPERATION
           ROLL OVER                                                TAKEOFF: VERTICAL
        PROBABLE CAUSE(S)
           DUAL STUDENT - IMPROPER OPERATION OF FLIGHT CONTROLS
           PILOT IN COMMAND - INADEQUATE SUPERVISION OF FLIGHT
        REMARKS- ONE ROTOR BLADE NOT FOUND
```

## Aircraft

- Registration: [N5901X](https://openairdocs.org/deregistered/N5901X-2020-04-03), registration cancelled 2020-04-03, S/N 36 (OpenAirDocs)
- Reported make and model: BRANTLY B-2
- Registry model: [Brantly B-2](https://openairdocs.org/model/brantly-b-2) (registry code 1440502) (OpenAirDocs)
- Category: Helicopter
- Engines: reciprocating
- Damage: Substantial damage
- Airport: Martha Lake

## Other investigations on N5901X (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 CEN18LA313](https://openairdocs.org/ntsb/CEN18LA313), Aug 3, 2018: Brantly B-2 (N5901X), Midland, MI, substantial damage. Probable cause: The in-flight separation of the tail rotor blade due to fatigue, which resulted in the subsequent emergency landing and dynamic rollover.

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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