ASN Wikibase Occurrence # 357329
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| Date: | Wednesday 29 May 1996 |
| Time: | 17:45 LT |
| Type: |  Dornier 328-110 |
| Owner/operator: | Horizon Air |
| Registration: | N336PH |
| MSN: | 3014 |
| Total airframe hrs: | 3846 hours |
| Engine model: | P&W PW119B |
| Fatalities: | Fatalities: 0 / Occupants: 23 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Billings, MT -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | , MT (KBIL) |
| Spokane, WA (KGEG) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Accident investigation:
 |
|
Sources:
NTSB SEA96IA104
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 16:41 | ASN Update Bot | Added |
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