# NTSB DEN89LA167: Piper PA-25, N6663Z, Wh Sulphur Spgs, MT, July 11, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 11, 1989, 14:45 local (20:45 UTC)
- Place: Wh Sulphur Spgs, MT
- Coordinates: 46.570991, -111.000373 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.5710&lon=-111.0004&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 18, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17744
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89LA167
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17744/pdf
- Page: https://openairdocs.org/ntsb/DEN89LA167

## Probable cause

THE PILOT FAILED TO MAINTAIN ADEQUATE AIRSPEED DURING AN AERIAL APPLICATION MANEUVER AND INADVERTENTLY ALLOWED THE AIRCRAFT TO MUSH INTO THE GROUND.  UNFAVORABLE WIND AND TURBULENCE WERE CONSIDERED TO BE CONTRIBUTING FACTORS.

## Sequence of events

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

- In flight collision with terrain/water, maneuvering - aerial application
  - weather condition - unfavorable wind (contributing factor)
  - weather condition - turbulence (contributing factor)
  - maneuver - initiated
  - airspeed - inadequate, pilot in command (cause)
  - stall/mush - inadvertent, pilot in command (cause)

## Analysis

THE PLT WAS ON AN AERIAL APPLICATION FLT, SPRAYING WEEDS NEXT TO HILLY TERRAIN. HE RPRTD THAT AS HE WAS IN A RIGHT TURN (LAST SPRAY RUN), THE ACFT ENCOUNTERED AN UNEXPECTED TAILWIND & EXTREME TURBULENCE. SUBSEQUENTLY, IT SETTLED & COLLIDED WITH THE GROUND.

## Aircraft

- Registration: [N6663Z](https://openairdocs.org/deregistered/N6663Z-1989-09-13), registration cancelled 1989-09-13, S/N 252263 (OpenAirDocs)
- Reported make and model: PIPER PA-25
- Registry model: [Piper PA-25-235](https://openairdocs.org/model/piper-pa-25-235) (registry code 7102504) (OpenAirDocs)
- Category: Airplane
- Serial number: 25-2263
- Engines: LYCOMING O-540 235 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Morgan, Boyd J., doing business as Quality Spraying
- Airworthiness certificate: Special, Restricted (Special)
- Departed: 7S6, WH SULPHUR SPGS, MT
- Destination: 7S6

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; flight hours: 3,674 total, 2,000 in this make and model, 330 in the last 90 days, 100 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 15 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F

## 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 19890711026369A](https://openairdocs.org/incident/19890711026369A), Jul 11, 1989: Piper PA25235, Sulphur Springs, MT, Substantial damage. Settled into ground impact turning downwind in a spray run turn around. Downdraft off a nearby hill.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.