Horizon Air Flight 2573
Dornier 328 · Incident: airframe, component or system failure en route
From Billings Logan International Airport (BIL) to Spokane International Airport (GEG)
Event
- NTSB case
- SEA96IA104
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Dornier 328
- Aircraft type
- Dornier 328
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N336PH
- Operator
- Horizon Air
- Onboard fatalities
- Unknown
- Route
- From Billings Logan International Airport (BIL), MTTo Spokane International Airport (GEG), Spokane, WA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · climb to cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Flt control syst, elevator trim/tab control › Foreign material/substance
- Flt control syst, elevator trim/tab control › Frozen
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The crew lost elevator trim after leveling at flight level (FL) 310, and they had to hold continuous control pressure to maintain level flight. Total air temperature was -50 degrees C at altitude. The captain elected to continue flight to the destination. Normal elevator trim operation was regained as the aircraft descended through 16,000 feet on its approach (total air temperature -7 degrees C); the flight subsequently landed without further incident. Postflight inspections of the elevator trim actuators by FAA inspectors revealed paint overspray on the elevator trim actuator push rods, scoring and corrosion on the push rods, and white desiccant windows on the actuators. The airline's FAA principal maintenance inspector (PMI) reported that there had been 10 unscheduled removals of DO-328 elevator trim actuators in the last 2-1/2 years for moisture and/or freezing in flight; that maintenance check cards did not address checking desiccant windows for moisture contamination or color criteria for checking the desiccant windows; that teardown reports from the vendor, AVIAC Technologies of France, indicated the paint overspray on the push rods was damaging the actuator quad rings during operation; and that he believed that damage to the quad rings was allowing moisture to enter the actuator housings.
Probable cause
paint overspray on the elevator trim actuator push rods, which damaged the actuator quad rings during normal operation and allowed water to enter the actuators; and the resultant freezing of the actuators. Factors relating to the incident included the aircraft manufacturer's failure to adequately protect the actuators from overspray during aircraft painting, insufficiently defined maintenance procedures by the aircraft manufacturer, and low temperatures at cruising altitude.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA96IA104
- Event ID
- 20001208X05866
- Case number
- SEA96IA104
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 1fd933e162af87736e77259d2c70d60d4222323a92351e141d7c557b289adf2e; retrieved 2026-09-18T17:50:25.429Z.