Narrative:While taxiing after a normal landing, a rumbling noise was heard from the vicinity of the nosegear, the hydraulic low pressure light illuminated and nosegear steering authority was lost. The right hand nosewheel had separated from the aircraft due to fracturing of the axle. As the nosewheel departed it damaged the nosegear uplock assembly with consequent loss of hydraulic system integrity. It then continued under the fuselage causing skin damage.
The nosewheel axle was recovered and subjected to metallurgical examination which showed that the fracture was due to fatigue. The fracture resulted from prior long term fatigue cracking which occupied approximately 75 of the cross sectional area of the axle. Stress corrosion cracks were present which were the most likely initiator of the fatigue cracks. A mandatory crack inspection requirement called up for this axle did not cover the specific area in which the stress corrosion was located. Consequently, during the axle refurbishment, the stress corrosion cracks were covered by a layer of electroplated chromium.
Probable Cause:
Significant Factors:
1. The nosewheel axle failed due to fatigue initiated by stress corrosion cracks.
2. The recurrent Non Destructive Inspection for the axles does not address the area where the stress corrosion occured. Consequently, pre- and post- refurbishment inspections did not detect the cracks.
Accident investigation:
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Investigating agency: | BASI |
Status: | Investigation completed |
Duration: | 289 days (10 months) | Accident number: | 198901542 | Download report: | Summary report
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Classification:
Damaged on the ground
Follow-up / safety actions
Upon advice of the failure mode by the Bureau, the operator carried out an inspection of all inservice and spare axles, to remove any axles with stress corrosion under the electroplated chromium.
ATSB issued 1 Safety Recommendation
Issued: 16-FEB-1990 | To: CAA Australia | VH-IPA(1) |
The Civil Aviation Authority consider extending the current mandatory Non Destructive Inspection for the axles, to address the area discovered in this accident. |
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Photos
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does
not display the exact flight path.
Distance from Sydney-Kingsford Smith International Airport, NSW to Melbourne-Tullamarine Airport, VIC as the crow flies is 703 km (440 miles).
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.