Statuts: | Accident investigation report completed and information captured |
Date: | mercredi 8 novembre 2017 |
Heure: | 19:38 |
Type/Sous-type: |  Avro RJ85 |
Compagnie: | Airlink |
Immatriculation: | ZS-ASW |
Numéro de série: | E2313 |
Année de Fabrication: | 1997-08-20 (20 years 3 months) |
Heures de vol: | 29636 |
Moteurs: | 4 Lycoming LF507-1F |
Equipage: | victimes: 0 / à bord: 4 |
Passagers: | victimes: 0 / à bord: 34 |
Total: | victimes: 0 / à bord: 38 |
Dégats de l'appareil: | Substantiels |
Lieu de l'accident: | au dessus de Limpopo province ( Afrique du Sud)
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Phase de vol: | En vol (ENR) |
Nature: | Transport de Passagers Intern. |
Aéroport de départ: | Harare Airport (HRE/FVHA), Zimbabwe |
Aéroport de destination: | Johannesburg-O.R. Tambo International Airport (JNB/FAOR), Afrique du Sud |
Numéro de vol: | SA8103 |
Détails:Airlink flight 8103 took off from Harare International Airport (FVHA) in Zimbabwe on an international scheduled flight to from Johannesburg, South Africa.
The Avro RJ85 took off at about 18:45 hours local time. At approximately 19:38 during cruise flight at a height of 34000 ft (FL340) within South African airspace, a loud bang was heard on the flight deck and a subsequent right yaw was experienced. The crew observed an immediate visual indication on the cockpit engines instruments that engines no. 1 and 2 had experienced catastrophic failure. According to the flight recordings, the no. 1 engine failed first. This was due to damage to the full authority digital electronic control (FADEC) box, which had been struck by the turbine blades debris from engine no.2.
Following the incident, the crew declared a MAYDAY call due to the instant failure of the two engines on the port wing, and immediately followed emergency operating procedures. Contact was made with the operator's maintenance control centre (MCC) to report and discuss the situation. A decision was then made by the crew following considered assessment of the situation to continue with the flight to the destination, a distance of approximately 240 nm. The aircraft landed uneventfully on runway 21R at 20:39.
It was found that that fourth-stage Low Pressure turbine rotor disc of engine no.2 had failed. The fourth-stage disc assembly was fitted on 27 July 2017 as a repaired unit which had a total of 11885 hours and 9419 cycles. During this disc change a wrong procedure was followed: pre-SB (Service Bulletin) engine configuration type procedure was applied during a post SB engine configured installation. During replacement of the fourth-stage disc assembly, a retaining nut that had been fitted before was reused and a new locking cup was used.
Probable Cause:
Probable Cause:
The cause of the no2 engine uncontained failure was attributed to the LP turbine retaining nut becoming dislodged resulting on the fourth-stage turbine rotor disk disengaged from the LP turbine shaft. The fourth-stage turbine rotor disc compromised the turbine casing and turbine debris from the no. 2 engine struck the no. 1 engine, causing an un-commanded shutdown and leading to a catastrophic failure of both port-side engines.
Contributory factor:
1. The incorrect application of torque settings; or improper installation due to a possible mis-stacking of the over-speed ring during maintenance.
Accident investigation:
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Investigating agency: | CAA SouthAfrica  |
Status: | Investigation completed |
Duration: | 1 year and 5 months | Accident number: | CA18/3/2/1185 | Download report: | Final report
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Sources:
» Airlink
Opérations de secours
CAA S.A. issued 1 Safety Recommendation
Issued: -- | To: CAA S.A. | ZS-ASW(1) |
It is recommended that the Director for Civil Aviation (DCA) publish an operator alert for dimension check reference in the EMM for on-wing fourth turbine rotor disc assembly maintenance procedure for post-SB ALF/LF 72-1030 engine configuration. During this investigation, it was revealed that the wrong dimension check reference diagram for pre-SB ALF/LF 72-1030 was used for an on-wing fourth turbine rotor disc assembly installation. In addition, there is no other reference of dimension reference for post-SB engine configuration in the AMM. Although agreement between the investigation team and both the engine and airframe manufacturers was reached, in consideration of the findings, to review and amend the AMM accordingly (which is subsequently underway), a prediction has been made that most of the engines in operation with similar post-SB configuration will soon require a fourth turbine rotor disc change due to time limit. It is therefore encouraged that an interim service advisory be communicated to operators regarding the dimension check reference in the EMM. |
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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 Harare Airport et Johannesburg-O.R. Tambo International Airport est de 955 km (597 miles).
Accident location: Approximate; accuracy within a few kilometers.
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.