Détails:
Lauda Air Flight 004 was a scheduled service from Hong Kong (HKG) back to Vienna (VIE), Austria. An intermediate stop was made in Bangkok (BKK), Thailand. The flight departed Bangkok at 23:02 hours. Some five minutes after takeoff the pilot-in-command stated "that keeps coming on," referring to a REV ISLN advisory warning. This indication appears when a fault has been detected in the thrust reverser system. The crew discussed the REV ISLN indication for about four and one-half minutes. The co-pilot read information from the Airplane Quick Reference Handbook as follows: "Additional systems failures may cause in- flight deployment" and "Expect normal reverser operation after landing." The pilot-in-command remarked "....its not just on, its coming on and off," he said, "...its just an advisory thing...," and shortly thereafter stated, "could be some moisture in there or something." At 23:12, the co-pilot advised the pilot-in-command that there was need for, "a little bit of rudder trim to the left." Fifteen minutes and one second into the flight the co-pilot exclaimed, "ah reverser's deployed," accompanied by sound similar to airframe shuddering, sounds of metallic snaps and the pilot-in-command stating "here wait a minute." With the deployment of the no. 1 engine thrust reverser, engine thrust was reduced to idle. Aerodynamic effects of the reverser plume in-flight during the engine run down to idle resulted in a 25 percent lift loss across the wing. The airplane stalled and entered an uncontrolled descent. Buffeting, maneuvering overload, and excessive speed caused pieces of the rudder and the left elevator to separate. This was followed by the down-and-aft separation of most of the right horizontal stabilizer from maneuvering overloads, as the crew attempted to control the airplane and arrest the high-speed descent. A torsional overload then caused the separation of the vertical and left horizontal stabilizers. The loss of the tail resulted in a sharp nose-over of the airplane, producing excessive negative loading of the wing. A downward wing failure was probably followed by the breakup of the fuselage. The complete breakup of the tail, wing, and fuselage occurred in a matter of seconds. The wreckage fell in mountainous jungle terrain.
PROBALE CAUSE: "The Accident Investigation Committee of the Government of Thailand determines the probable cause of this accident to be uncommanded in-flight deployment of the left engine thrust reverser, which resulted in loss of flight path control. The specific cause of the thrust reverser deployment has not been positively identified."
» Aviation Week & Space Technology 03.06.1991 (32), 10.06.91 (28-30)
accident date: 26-05-1991
type: Boeing 767-3Z9ER
registration: OE-LAV
| Statuts: | Accident investigation report completed and information captured |
| Date: | dimanche 26 mai 1991 |
| Heure: | 23:17 |
| Type/Sous-type: |  Boeing 767-3Z9ER |
| Compagnie: | Lauda Air |
| Immatriculation: | OE-LAV |
| Numéro de série: | 24628/283 |
| Année de Fabrication: | 1989-09-26 (1 year 8 months) |
| Heures de vol: | 7429 |
| Cycles: | 1132 |
| Moteurs: | 2 Pratt & Whitney PW4060 |
| Equipage: | victimes: 10 / à bord: 10 |
| Passagers: | victimes: 213 / à bord: 213 |
| Total: | victimes: 223 / à bord: 223 |
| Dégats de l'appareil: | Détruit |
| Conséquences: | Written off (damaged beyond repair) |
| Lieu de l'accident: | 5,6 km (3.5 milles) NNE of Phu Toey ( Thaïlande)
|
| Phase de vol: | En vol (ENR) |
| Nature: | Transport de Passagers Intern. |
| Aéroport de départ: | Bangkok-Don Muang International Airport (BKK/VTBD), Thaïlande |
| Wien-Schwechat International Airport (VIE/LOWW), Autriche | |
| Numéro de vol: | NG004 |
Lauda Air Flight 004 was a scheduled service from Hong Kong (HKG) back to Vienna (VIE), Austria. An intermediate stop was made in Bangkok (BKK), Thailand. The flight departed Bangkok at 23:02 hours. Some five minutes after takeoff the pilot-in-command stated "that keeps coming on," referring to a REV ISLN advisory warning. This indication appears when a fault has been detected in the thrust reverser system. The crew discussed the REV ISLN indication for about four and one-half minutes. The co-pilot read information from the Airplane Quick Reference Handbook as follows: "Additional systems failures may cause in- flight deployment" and "Expect normal reverser operation after landing." The pilot-in-command remarked "....its not just on, its coming on and off," he said, "...its just an advisory thing...," and shortly thereafter stated, "could be some moisture in there or something." At 23:12, the co-pilot advised the pilot-in-command that there was need for, "a little bit of rudder trim to the left." Fifteen minutes and one second into the flight the co-pilot exclaimed, "ah reverser's deployed," accompanied by sound similar to airframe shuddering, sounds of metallic snaps and the pilot-in-command stating "here wait a minute." With the deployment of the no. 1 engine thrust reverser, engine thrust was reduced to idle. Aerodynamic effects of the reverser plume in-flight during the engine run down to idle resulted in a 25 percent lift loss across the wing. The airplane stalled and entered an uncontrolled descent. Buffeting, maneuvering overload, and excessive speed caused pieces of the rudder and the left elevator to separate. This was followed by the down-and-aft separation of most of the right horizontal stabilizer from maneuvering overloads, as the crew attempted to control the airplane and arrest the high-speed descent. A torsional overload then caused the separation of the vertical and left horizontal stabilizers. The loss of the tail resulted in a sharp nose-over of the airplane, producing excessive negative loading of the wing. A downward wing failure was probably followed by the breakup of the fuselage. The complete breakup of the tail, wing, and fuselage occurred in a matter of seconds. The wreckage fell in mountainous jungle terrain.
Probable Cause:
PROBALE CAUSE: "The Accident Investigation Committee of the Government of Thailand determines the probable cause of this accident to be uncommanded in-flight deployment of the left engine thrust reverser, which resulted in loss of flight path control. The specific cause of the thrust reverser deployment has not been positively identified."
Sources:
» SKYbrary » Aviation Week & Space Technology 03.06.1991 (32), 10.06.91 (28-30)
Opérations de secours
The Thai Aircraft Accident Investigation Committee recommended that the United States FAA examine the certification philosophy of all airplane certificated with ground only engine thrust reverser systems to provide appropriate design safeguards to prevent in-flight deployment.
The Aircraft Accident Investigation Committee also recommends that the FAA revise the certification standards for current and future airplane flight recorders intended for use in accident investigation to protect and preserve the recorded information from the conditions of prolonged thermal exposure that can be expected in accidents which occur in locations that are inaccessible for fire fighting efforts. FAA issued 6 Airworthiness Directives
NTSB issued 4 Safety Recommendations
Show all...
The Aircraft Accident Investigation Committee also recommends that the FAA revise the certification standards for current and future airplane flight recorders intended for use in accident investigation to protect and preserve the recorded information from the conditions of prolonged thermal exposure that can be expected in accidents which occur in locations that are inaccessible for fire fighting efforts. FAA issued 6 Airworthiness Directives
NTSB issued 4 Safety Recommendations
Show all...
Photos
accident date: 26-05-1991
type: Boeing 767-3Z9ER
registration: OE-LAV
Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Bangkok-Don Muang International Airport et Wien-Schwechat International Airport est de 8375 km (5235 miles).
Accident location: Exact; as reported in the official accident report.
La distance entre Bangkok-Don Muang International Airport et Wien-Schwechat International Airport est de 8375 km (5235 miles).
Accident location: Exact; as reported in the official accident report.
Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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