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Statuts:Enquête Officielle
Date:mercredi 11 mai 1994
Heure:15:30
Type/Sous-type:Silhouette image of generic BE20 model; specific model in this crash may look slightly different
Beechcraft B200C Super King Air
Compagnie:New South Wales Department of Health
Immatriculation: VH-AMM
Numéro de série: BL-125
Année de Fabrication: 1985
Equipage:victimes: 0 / à bord:
Passagers:victimes: 0 / à bord:
Total:victimes: 0 / à bord:
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:Dubbo Airport, NSW (DBO) (   Australie)
Phase de vol: A l'atterrissage (LDG)
Nature:Ambulance
Aéroport de départ:Brewarrina Airport, NSW (BWQ/YBRW), Australie
Aéroport de destination:Dubbo Airport, NSW (DBO/YSDU), Australie
Détails:
After arriving in the circuit area of Dubbo Airport, Australia, the pilot extended the landing gear and obtained the correct down and locked indications. The right main gear leg subsequently collapsed during the landing roll.
The retract actuator trunnion bearings had collapsed, allowing excessive movement of the actuator in its mount. This resulted in insufficient travel of the actuator to fully engage the downlock. Two separate occurrences involving unsafe landing gear indications, which had been corrected in flight by recycling, had been reported to the operator's maintenance staff prior to the accident. The maintenance staff, unable to duplicate the defect on the ground, had adjusted the downlock switch. Those adjustments finally resulted in the switch jamming in the closed position, giving a safe indication.
The downlock switch has two functions, providing independent safe/unsafe indications of the lock and, in series with the nose and left leg switches, removal of electrical power to the hydraulic pump when the three downlocks are sensed in a locked condition. On the accident flight, with the right downlock switch jammed in the closed position, hydraulic pressure was terminated when the left and nose gears locked down. As the lock function of the right gear lock was compromised because of the failed trunnion bearings, the leg collapsed under the landing loads. Investigation of the aircraft maintenance requirements determined that the landing gear actuator trunnion bearings had been incorrectly identified as sealed bearings requiring no lubrication. The bearings fitted to the aircraft were of the unsealed type, with a requirement for lubrication every 1000 landings or 30 months.

Accident investigation:
cover
Investigating agency: BASI
Status: Investigation completed
Duration: 2 years and 3 months
Accident number: 199401233
Download report: Summary report
Language: English

Sources:
» ATSB


Opérations de secours
As a result of the investigation into this occurrence, two other B200C aircraft from the same operator were found to have similar unsealed bearings fitted to the main landing gear actuator trunnion bearings. The operator has taken action to amend the aircraft inspection schedule to include lubrication of unsealed bearings and initiated a retirement life program for all sealed bearings.

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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 Brewarrina Airport, NSW et Dubbo Airport, NSW est de 299 km (187 miles).

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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