Why Titanium Bolts Fail--A Not So Common Cause
Nate Anglin
CEO @ Skylink Group - Optimizing Global Nose-to-Tail Aircraft Mx Material Needs | I Help Empower B2B Leaders to Reduce Overwhelm, Boost Team Effectiveness & Reclaim Their Greatest Investment—Time.
Two titanium alloy wing attachment bolts from a commercial airline failed during the course of a routine service operation.
And there was a series of aircraft bolts fitted on a landing gear assembly that failed within a few months of each other.
This was a trigger to look closer.
Especially when these bolts are made of Titanium…and Titanium parts are expensive for a very good reason.
‘A picture is worth a 1,000 words’
FAILURE INVESTIGATION
As with every failure investigation an analysis of the failed parts is the starting point. This includes the use of an optical microscope, which is quite revealing in most cases.
Employing a more extended array of tools during a failure investigation may seem like a good strategy to tackle complex problems.
But then you must think…
What about time? What about cost? When it comes to an effective investigation the tools are as good (or as bad) as the engineer performing the task.
Questions can lead to answer, with common ones being:
- Is it fatigue?
- What about excessive static load during service?
- Any material quality issues or flaws?
THE HUMAN FACTOR
Coming up with the right questions is difficult though and it actually requires very well developed engineering judgment. This does not involve simply assembling all the data but most importantly connecting the dots between the failure investigation findings and probable causes.
History can be helpful in that regard…
“A number of aircraft have been operated over a period of three years of service following a major maintenance and system upgrade visit at an MRO facility.”
“Three out of these aircraft are now experiencing a fracture bolt fitted on the landing gear assembly.”