Fokker F28 MK0100 N850US
11 November 1990 · Atlanta, Georgia, United States · No injuries
Summary
On 11 November 1990 at about 23:10 local time, a Fokker F28 MK0100 registered N850US, operated by Usair, was involved in an incident near Atlanta, Georgia, United States. 75 people were on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.
The record
- Date
- at 23:10
- Classification
- Incident
- Location
- Atlanta, Georgia, United States
- Coordinates
- Not recorded
- Aircraft
- Fokker F28 MK0100
- Registration
- N850US
- Category
- Airplane
- Engines
- 2
- Operator
- Usair
- Operating rule
- Part 121: Air Carrier
- Purpose of flight
- Unknown
- Phase of flight
- Not recorded
- Route
- Philadelphia → Atlanta
- Aircraft damage
- Not recorded
- Weather
- VMC
- Light
- Dusk
- NTSB number
- ATL91IA017
People
Nobody was injured.
| On board | Died | Serious | Minor | Uninjured |
|---|---|---|---|---|
| 75 | 0 | 0 | 0 | 75 |
Probable cause
FROZEN MOISTURE IN THE STABILIZER ACTUATOR HYDRAULIC SERVO VALVE WHICH RESULTED IN REDUCED MOVEMENT OF THE SERVO VALVE AND LIMITED ITS ABILITY TO RESPOND TO FLIGHT CONTROL INPUTS. THE LACK OF RESPONSE FROM THE SERVO VALVE RESULTED IN THE JAMMED STABILIZER MESSAGE. A FACTOR WAS THE INADEQUATE DESIGN OF THE SERVO VALVE WHICH PRECLUDED MOISTURE DRAINAGE.
Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.
Read the full NTSB narrative
DURING DESCENT THE AFCAS STABILIZER TRIM & AUTOPILOT DISENGAGED. BOTH WERE RESET WITH A 2ND DISENGAGEMENT. NOSE DOWN CONTROL PRESSURES WERE ENCOUNTERED & THE FLT CREW ATTEMPTED TO USE MANUAL TRIM, FOLLOWED BY A JAMMED STABILIZER MASTER WARNING. AFCAS STABILIZER TRIM WAS LEFT OFF IAW ABNORMAL PROCEDURES. FDR DATA SHOWED THE STAB THEN CREEPED TO A FULL ACFT NOSE DOWN POSITION & HYD PRES TO THE STAB ACTUATOR WAS AUTOMATICALLY REMOVED, PER DESIGN. SUBSEQUENT TESTING OF THE HORIZONTAL STABILIZER CONTROL UNIT ASSEMBLY SHOWED THAT, AFTER SPRAYING THE SERVO VALVE WITH WATER AND COLD SOAKING, ICE WOULD FORM INSIDE THE END CAP AND A JAMMED SERVO VALVE CONDITION WOULD OCCUR. THE END CAP AND SPRING EXHIBITED SUBSTANTIAL RUST CORROSION. CREW MOVEMENT OF THE MANUAL TRIM RESULTED IN THE JAMMED STAB WARNING.
Quoted verbatim from the NTSB record.
Other Fokker F28 accidents
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 22 Jun 1992 | Fokker F.28 MK 1000 | Portland, Oregon, United States | Timeair Inc. | No injuries | - |
| 14 Apr 1988 | Fokker F28 MK 4000 | Charleston, West Virginia, United States | - | Minor injuries | - |
| 15 Apr 1992 | Fokker F.28 MK4000 | Charlotte, North Carolina, United States | Usair | No injuries | - |
| 7 May 1993 | Fokker F28-MK-0100 | Pittsburgh, Pennsylvania, United States | Usair | Minor injuries | - |
| 30 Dec 1986 | Fokker F28 MK4000 | West Palm Bch, Florida, United States | - | Serious injuries | - |
| 1 May 1994 | Fokker F28 MK 0100 | Charlotte, North Carolina, United States | Usair, Inc. | No injuries | - |
Other accidents in this area
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 30 Sep 1990 | Cessna 210 | White Plains, Georgia, United States | Grecol Aviation, Inc. | No injuries | - |
| 26 Mar 1990 | Hughes 369E | Buford, Georgia, United States | Gwinnett County Board of Comm | No injuries | - |
| 2 Aug 1990 | Cessna 185A | Americus, Georgia, United States | GA Forestry Commission | No injuries | - |
| 15 Jun 1990 | Hughes TH-55 | Brunswick, Georgia, United States | Glynn Cunty | No injuries | - |
| 21 Nov 1990 | Cessna 182E | Blairsville, Georgia, United States | Hoots, Mayme L. | Fatal | 1 |
| 30 Dec 1990 | Beechcraft B95 | Austell, Georgia, United States | Luther, Mark | Fatal | 1 |