# NTSB DEN86LA236: Mayala Dragonfly, N4478V, Helena, MT, August 25, 1986

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: August 24, 1986, 19:49 local (Aug 25, 1986, 01:49 UTC)
- Place: Helena, MT
- Coordinates: 46.530033, -112.210678 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.5300&lon=-112.2107&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 17039
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN86LA236
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17039/pdf
- Page: https://openairdocs.org/ntsb/DEN86LA236

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, approach - vfr pattern - final approach
  - throttle/power lever,cable - bent (cause)
  - proper glidepath - below, pilot in command (contributing factor)
  - throttle/power lever,cable - binding(mechanical) (cause)
  - throttle/power control - initiated, pilot in command (cause)
  - carburetor heat - not used, pilot in command (contributing factor)
- Undershoot, approach - vfr pattern - final approach
- In flight collision with terrain/water, approach - vfr pattern - final approach
  - terrain condition - mountainous/hilly (contributing factor)

## Analysis

THE ACFT WAS ON FINAL APCH AFTER COMPLETING A X-COUNTRY FROM BILLINGS, MT, WHEN THE ACCIDENT OCCURRED. THE PLT STATED THE ACFT WAS LOW AFTER INTERCEPTING THE VASI SO POWER WAS ADDED; HOWEVER, THE ENG DID NOT RESPOND. THE ACFT STRUCK A SMALL HILL 300 FT SHORT OF RWY. INSPECTION FOUND NO EVIDENCE OF MECHANICAL FAILURE OF THE ENGINE BUT THE UPPER CABLE FROM THROTTLE CONTROL-TO-CARBURETOR LINKAGE WAS BENT AND THE WALKING BEAM SHOWED EVIDENCE OF BINDING. ADDITIONALLY, NO EVIDENCE OF CABLE LUBRICATION WAS NOTED.

## Aircraft

- Registration: [N4478V](https://openairdocs.org/deregistered/N4478V-2013-06-11), registration cancelled 2013-06-11, S/N 437, built 1985 (OpenAirDocs)
- Reported make and model: MAYALA DRAGONFLY
- Registry model: [Mayala Hjalmer A DRAGONFLY](https://openairdocs.org/model/mayala-hjalmer-a-dragonfly) (registry code 05644HV) (OpenAirDocs)
- Registry engine: [Volkswagen CONVERSION](https://openairdocs.org/engine/volkswagen-conversion) (registry code 63501, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 437
- Airframe hours: 155
- Engines: HAPI 60-2DM 60 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Hjalmer A. Mayala
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, August 26, 1985, 50 hours before
- Departed: BIL, BILLINGS, MT
- Airport: HLN, Helena Regional, runway 26, 9,000 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 304 total, 144 in this make and model, 276 as pilot in command, 50 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 7 knots
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 41 °F
- Altimeter: 29.00 inHg
- Observed at: HLN

## 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 19860824041949A](https://openairdocs.org/incident/19860824041949A), Aug 24, 1986: Amtr DRAGONFLY, Helena, MT, Substantial damage. Engine failed on short final. Aircraft landed short of runway. Throttle cable found binding.

## Other investigations on N4478V (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 SEA98LA192](https://openairdocs.org/ntsb/SEA98LA192), Sep 30, 1998: Mayala Dragonfly (N4478V), Avon, MT, destroyed. Probable cause: Failure of the engine crankshaft aft oil seal resulting in the loss of engine oil, and rough terrain during the forced landing.

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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