# NTSB FTW84FA374: Miller Air Sports GEM 260, N177M, Martindale, TX, September 1, 1984

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: September 1, 1984, 11:15 local (16:15 UTC)
- Place: Martindale, TX
- Coordinates: 30.529766, -98.380844 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.5298&lon=-98.3808&mi=10
- Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21147
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW84FA374
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21147/pdf
- Page: https://openairdocs.org/ntsb/FTW84FA374

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, unknown
  - design stress limits of aircraft - exceeded, pilot in command (cause)
  - overconfidence in aircraft's ability, pilot in command (contributing factor)
  - propeller system/accessories,blade - separation (contributing factor)
  - stabilizer - overload
  - stabilizer - disintegrated
  - wing - overload
  - wing - disintegrated
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

NOTES LEFT BY PLT INDICATE HE HAD BEEN TESTING THE FLIGHT ENVELOPE OF THIS EXPERIMENTAL RACING ACFT, INCLUDING OPERATION OF THE ENGINE BEYOND PROP LIMIT OF 4000 RPM. WITNESSES HEARD ENGINE SOUND SUDDENLY SPEED UP TO HIGH RPM THEN CEASE ALTOGETHER. SOME WITNESSES REPORTED HEARING AN EXPLOSIVE SOUND. ACFT WRECKAGE WAS SCATTERED OVER 1-1/2 MILES. HORIZONTAL AIRFRAME SURFACES WERE DISINTEGRATED; LARGEST PIECE WEIGHED LESS THAN 10 LBS. 3 PROP BLADES (WOOD CORE) HAD SEPARATED 8' OUTBOARD OF HUB; FOURTH BLADE SEPARATED INSIDE SPINNER. ONLY ONE BLADE WAS RECOVERED. EXAMINATION OF AIRFRAME FRACTURES REVEALED SEPARATIONS OCCURRED ALONG MULTIPLE AXES; SIGNATURES IN CONVENTIONAL MATERIALS SHOWED CHARACTERISTICS OF GROSS OVERLOAD. COMPOSITE MATERIAL SEPARATIONS PARALLELED WARP OF 'CLOTH' EXCEPT IN AREAS OF HIGH PEEL STRESS. ALL COMPOSITE STRUCTURES EXHIBITED UNIFORM SATURATION OF RESIN; NO AIR BUBBLES FOUND IN LAYUP.

## Aircraft

- Registration: [N177M](https://openairdocs.org/deregistered/N177M-2013-06-11), registration cancelled 2013-06-11, S/N M-103, built 1984 (OpenAirDocs)
- Reported make and model: MILLER AIR SPORTS GEM 260
- Registry model: [Miller James W GEM 260](https://openairdocs.org/model/miller-james-w-gem-260) (registry code 05613FX) (OpenAirDocs)
- Registry engine: [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series) (registry code 17020, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: M-103
- Airframe hours: 51
- Engines: CONTINENTAL O-200-B 100 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: James W. Miller
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Unknown, July 9, 1984, 19 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; toxicology performed; flight hours: 27,487 total, 1 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 160° at 5 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 72 °F
- Altimeter: 30.00 inHg
- Observed at: AUS, 30 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19840901045059A](https://openairdocs.org/incident/19840901045059A), Sep 1, 1984: Amtr GEM260, Martindale, TX, Destroyed. Propeller blade failure caused airframe break up during test flight. Notes indicate prop was run over max. Rpms.

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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