Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Boston, Massachusetts 02128
Friday, June 14, 1996 10:57 EDT
NTSB Narrative Summary Released at Completion of Accident
The pilot reported that a two to three degree uncommanded pitch decrease occurred about 600 feet above ground level at the same time as a flight control system pitch warning fault message was received. The crew declared an emergency and landed without further incident. During troubleshooting, the maintenance technician reported the right half of the stabilizer trim control package felt hot to the touch. The left side was cool. The trimmable horizontal stabilizer (THS) actuator was replaced, and the airplane was returned to service without further incident. Examination of the airplane logbooks revealed flight control system, pitch axis, discrepancies, and maintenance action following the previous two flights. Both elevator aileron computers, the THS electronic module, the THS actuator position monitor, and the pitch trim motor were replaced. Examination of the flight data recorder revealed erratic stabilizer movement on the previous two flights. The THS actuator and the pitch trim actuator servo motor functioned normally when tested. A defective diode was discovered in the electronic module. An Airbus Industries engineer reported the pitch oscillations could not be attributed to the defective diode.
NTSB Probable Cause Narrative
an undetermined intermittent fault in the trimmable horizontal stabilizer actuator system.
Event Information
| Type of Event | Incident |
| Event Date | 6/14/1996 |
| Event Day of the Week | Friday |
| Time of Event | 1057 |
| Event Time Zone | Eastern Daylight Time |
| Event City | BOSTON |
| Event State | MASSACHUSETTS |
| Event Country | -- |
| Zipcode of the event site | 02128 |
| Event Date Year | 1996 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | |
| Event Location Nearest Airport ID | |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Pilot |
| Time of the weather observation | 0 |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | |
| Elevation of weather observation facility | 0 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 27 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 0 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 0 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 28 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 106 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 5032 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Jun 17 1996 12:00AM |
| NTSB Notification Time | 900 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 8 2000 10:03AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N347NW |
| NTSB Number | CHI96IA207 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | -- |
| Damage | None |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Airbus Industrie |
| Aircraft Model | A-320 |
| Aircraft Series Identifier | A320 |
| Aircraft Serial Number | 408 |
| Certified Max Gross Weight | 167000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 156 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | Feb 10 1996 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 10754 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | WILMINGTON TRUST COMPANY |
| Aircraft Owner Street Address | 110 N. MARKET STREET |
| Aircraft Owner City | WILMINGTON |
| Aircraft Owner State | DE |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 19890 |
| Operator is an individual? | -- |
| Operator Name | NORTHWEST AIRLINES |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 5101 NORTHWEST DRIVE |
| Operator City | ST. PAUL |
| Operator State | MN |
| Operator Country | |
| Operator Zip code | 55111 |
| Operator Code | NWAA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | Yes |
| Departure Airport Code | BOS |
| Departure City | |
| Departure State | |
| Departure Country | |
| Departure Time | 1043 |
| Departure Time Zone | EST |
| Destination Same as Local Flt | -- |
| Destination Airport Code | DTW |
| Destination City | DETROIT |
| Destination State | MI |
| Destination Country | |
| Specific Phase of Flight | Takeoff |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Sep 28 2001 1:03PM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |