# NTSB SEA95IA102: Fairchild SA227-AC, N2727B, Spokane, WA, May 17, 1995 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: May 17, 1995, 06:30 local (13:30 UTC) - Place: Spokane, WA - Location: 47.6588° N, 117.4260° W: Placed by OpenAirDocs: center of Spokane, WA, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=47.6588&lon=-117.4260&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 17 uninjured - Status: Completed, report September 24, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 42072 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA95IA102 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42072/pdf - Page: https://openairdocs.org/ntsb/SEA95IA102 ## Probable cause A SHORTED ELECTRICAL WIRING ON THE ELEVATOR TRIM SYSTEM. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - electrical system,electric wiring - shorted (cause) - flt control syst,elevator trim/tab control - uncommanded ## Analysis WHILE IN CRUISE FLIGHT, THE FLIGHT CREW REPORTED THAT THERE WAS AN INTERMITTENT SONALERT FOR THE TRIM IN MOTION, HOWEVER, NEITHER THE TRIM INDICATOR NOR THE AIRCRAFT TRIM WERE AFFECTED AT THIS TIME. SOME MINUTES LATER, THE ELEVATOR TRIM BEGAN TO MOVE WITHOUT CREW INPUT. BOTH THE CAPTAIN AND THE CO-PILOT TRIED TO DEACTIVATE THE TRIM FROM THEIR CONTROL YOKE SWITCHES; HOWEVER, THE TRIM WOULD NOT DEACTIVATE UNTIL THE LEFT SIDE ESSENTIAL BUS WAS SELECTED OFF. THE AIRPLANE THEN LANDED WITHOUT FURTHER INCIDENT. INSPECTION OF THE SYSTEM REVEALED THAT THE CAPTAIN'S SIDE TRIM POWER WIRE WAS SHORTED DIRECTLY TO THE LEFT SIDE ESSENTIAL BUS, AND THE JUMPER WIRE AT THE CAPTAIN'S YOKE TRIM (GROUND SIDE) SWITCH WAS SHORTED TO THE YOKE. AFTER THE WIRES WERE REPLACED, THE SYSTEMS OPERATION CHECKED OK. ## Factual narrative On May 17, 1995, at 0630 Pacific daylight time, a Fairchild SA227-AC, N2727B, operating as Horizon Air flight 2342, experienced a runaway trim while cruising at 19,000 feet, en route to Spokane, Washington. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed for the flight that was conducted under 14CFR135. The airplane was not damaged and neither the airline transport pilot, commercial pilot or 15 passengers were injured. The flight had departed from Portland, Oregon, on May 17, 1995, at 0600. The flight landed at Spokane, without further incident, at 0720. The flight crew reported that while cruising at 19,000 feet, there was an intermittent sonalert for the trim in motion. At this time the trim indicator and the aircraft trim were not affected. The captain stated that some minutes later, and just prior to descent, the elevator trim began to move without any input. The captain deactivated the trim on his control yoke, however, the runaway continued. The control was then switched to the co-pilot's position, however, the co-pilot's control would not deactivate the trim. The left side essential bus was then selected off, which deactivated the trim. The airplane then landed without further incident. The captain reported that the trim runaway and DC bus fail checklists were complied with. Maintenance personnel at Horizon Air reported that the captain's side trim power wire was found shorted directly to the left hand essential bus, and the jumper wire at the captain's yoke trim (ground side) switch was found shorted to the yoke. These wires were replaced and the systems operation checked ok. ## Aircraft - Registration: [N2727B](https://openairdocs.org/deregistered/N2727B-1996-12-09), registration cancelled 1996-12-09, S/N AC730 (OpenAirDocs) - Reported make and model: FAIRCHILD SA227-AC - Registry model: [Fairchild SA227-AC](https://openairdocs.org/model/fairchild-sa227-ac) (registry code 3377509) (OpenAirDocs) - Category: Airplane - Serial number: AC-730 - Airframe hours: 15127 - Engines: GARRETT TPE-331 900 horsepower turbo prop - Damage: No damage - Flight: Part 135 - Registered owner: Horizon Air - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, May 8, 1995, 32 hours before - Departed: PDX, PORTLAND, OR - Destination: GEG, WA - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 8,000 total, 4,060 in this make and model, 7,200 as pilot in command, 180 in the last 90 days, 72 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 11 knots - Visibility: 15 statute miles - Lowest ceiling: 1,500 ft broken - Temperature: 52 °F, dew point 46 °F - Altimeter: 29.00 inHg - Observed at: GEG ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19950517015479I](https://openairdocs.org/incident/19950517015479I), May 17, 1995: Swrngn SA227AC, Spokane, WA. Narrative: during a routine IFR flight at 19,000 feet the captain's pitch trim sonalert intermittent tone with no trim input. Pitch trim began to move without… 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.