Dornier 328 N336PH

Summary

On 29 May 1996 at about 22:45 local time, a Dornier 328 registered N336PH, operated by Horizon Air, was involved in an incident near Billings, Montana, United States. 23 people were on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

29 May 1996 at 22:45

Classification

Incident

Location

Billings, Montana, United States

Coordinates

45.6509, -108.3792

Aircraft

Dornier 328

Registration

N336PH

Category

Airplane

Engines

2

Operator

Horizon Air

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Unknown → Spokane

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

SEA96IA104

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full 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.

Quoted verbatim from the NTSB record.