# NTSB DEN89FA076: Swearingen SA226TC, N1010Z, Saint George, UT, February 11, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: February 10, 1989, 17:25 local (Feb 11, 1989, 00:25 UTC)
- Place: Saint George, UT
- Coordinates: 37.1804, -113.600028 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.1804&lon=-113.6000&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 6 uninjured
- Status: Completed, report April 24, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17580
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89FA076
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17580/pdf
- Page: https://openairdocs.org/ntsb/DEN89FA076

## Probable cause

MALFUNCTION OF THE NOSEWHEEL STEERING SYSTEM DUE TO IMPROPER INSTALLATION OF THE NOSEWHEEL STEERING POPPET VALVE & INADEQUATE MAINTENANCE INSTRUCTIONS.

## Sequence of events

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

- Airframe/component/system failure/malfunction, takeoff
  - landing gear,steering system - incorrect (cause)
  - maintenance,replacement - improper, company maintenance personnel (cause)
  - procedure inadequate, manufacturer (cause)
  - condition(s)/step(s) insufficiently defined
- Loss of control - on ground/water, takeoff - roll/run
  - directional control - not maintained
  - ground loop/swerve - uncontrolled
- On ground/water collision with object, takeoff - aborted
  - object - aircraft parked/standing
  - object - vehicle

## Analysis

DRG THE TAKEOFF ROLL WITH THE COPLT AT THE CTLS, THE ACFT BEGAN TURNING TO THE LEFT. THE COPLT CORRECTED WITH RGT RUDDER, BUT AS THE TAKEOFF CONTD, THE ACFT VEERED UNCONTROLLABLY TO THE LEFT. THE TAKEOFF WAS ABORTED, BUT BEFORE STOPPING, THE ACFT TURNED FURTHER LEFT & HIT A CESSNA 172 & A UPS VEHICLE, BOTH OF WHICH WERE UNOCCUPIED. THIS WAS THE 1ST FLT AFTER MAINT ON THE NOSEWHEEL STEERING SYS. A SYS CHECK REVEALED THAT WHEN HYDRAULIC & ELECTRICAL PWR WERE APPLIED, THE NOSEWHEEL STEERING SYS WOULD DEFLECT TO THE LEFT AT A RATE OF ABOUT ONE DEGREE PER SECOND. INVESTIGATION REVEALED THAT WHEN MAINT WAS PERFORMED, A ONE-PIECE ARMING/POPPET VLV WAS USED TO REPLACE A TWO-PIECE VLV, WHICH WAS PREVIOUSLY INSTALLED. DRG THE INSTLN, THE SMALL PART OF THE TWO-PIECE VLV (ABT THE SIZE OF A WASHER) WAS NOT REMOVED. WHEN THE ONE-PIECE VLV WAS INSTLD PROPERLY, THE SYS OPERD NORMALLY. MAINT INSTRNS & DRAWINGS DID NOT ADDRESS THE TW0- PIECE VLV & NO INSTRNS WERE FND TO INDC THE TWO PIECES OF THE OLD VLV SHOULD BE CHGD AS A PACKAGE.

## Aircraft

- Registration: [N1010Z](https://openairdocs.org/deregistered/N1010Z-1990-08-29), registration cancelled 1990-08-29, S/N TC373 (OpenAirDocs)
- Reported make and model: SWEARINGEN SA226TC
- Registry model: [Swearingen SA226TC](https://openairdocs.org/model/swearingen-sa226tc) (registry code 8780404) (OpenAirDocs)
- Category: Airplane
- Serial number: TC-373
- Airframe hours: 16361
- Engines: AIRESEARCH TPE-331 940 horsepower turbo prop
- Damage: Substantial damage
- Flight: Positioning, Part 91
- Registered owner: Skywest Airlines, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Continuous airworthiness, February 7, 1989, 2 hours before
- Departed: SGU
- Destination: PSP, PALM SPRINGS, CA
- Flight plan: IFR
- Airport: SGU, Saint George, runway 16, 6,100 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 7,282 total, 1,825 in this make and model, 4,736 as pilot in command, 148 in the last 90 days, 55 in the last 30 days, 9 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 46 °F
- Altimeter: 30.00 inHg
- Observed at: SGU, 1 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 19890210003489A](https://openairdocs.org/incident/19890210003489A), Feb 10, 1989: Swrngn SA226TC, Saint George, UT, Substantial damage. Uncommanded turn on takeoff roll. Aborted. Left runway hit parked aircraft. Improper repair steering selenoid.

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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