Reference

Wing spar failure due to extreme overload can be indicated by several factors. These include:

1. Visual Inspection: Physical examination may reveal deformations or cracks in the wing structure that suggest the wing was subjected to forces beyond its design limits.

2. Material Failure: The wing spar material could show signs of yielding or breaking at points of high stress concentration, indicating it failed due to an overload.

3. Accident Reports: Historical data from similar incidents, such as the Ansett-ANA Flight 325 where the wing spar failed in upward bending due to extreme overload, can provide context.

4. Investigation Findings: Reports often detail specific signs of overload, such as the absence of pre-existing cracks or material anomalies that would suggest a different cause of failure.

5. Maintenance Records: Reviewing maintenance and service logs can help determine if there were any previous issues or if the aircraft was subjected to repeated extreme loads that could lead to spar failure.

6. Flight Data: Black box data or other flight recorder information can provide insights into the forces experienced by the aircraft just before the failure.

7. Witness Accounts: Pilots or observers who experienced or saw the incident can provide accounts that may indicate a sudden or extreme event that could cause an overload.

8. Structural Analysis: Detailed analysis of the broken components can reveal evidence of overload, such as specific fracture patterns or material deformations.

In conclusion, a combination of these indicators, supported by expert analysis and historical context, can confirm that a wing spar failed due to extreme overload.