When Pratt & Whitney accused a supplier in late August of furnishing defective titanium for the F135 engine on the Lockheed Martin F-35, it was easy – but not entirely correct – to connect the problem to a string of component reliability failures and supplier management miscues already connected to the programme.

Although the F-35 has earned a reputation over a prolonged development period, that focus may conceal a deeper problem inside the US domestic titanium supply base that goes well beyond the single-engined stealth fighter.

P&W has sued A&P Alloys for allegedly supplying titanium sourced from Russia – the world’s largest titanium producer – and for concerns about the quality of the lightweight, high-strength metal delivered for the F135. According to P&W, the suspect titanium forced the company to suspend engine deliveries for several weeks.

A&P is not the first company to supply suspect titanium to the Department of Defense. Indeed, court documents show that faulty titanium products have triggered a 15-year-long string of aircraft groundings and lawsuits, affecting the Bell Boeing V-22, Boeing C-17, Boeing F-15, Lockheed F-22 and now the F-35.

In response, the Department of Defense convened a task force in 2009 dedicated to examining the problem of suspect titanium in the US military aircraft supply base. Based on their findings, last April NASA published a handbook for government acquisition managers to identify defective shipments of finished titanium.

The published reports make it clear that the fault does not lie with the producers of raw titanium bar and plate, such as TIMET, ATI and RTI.

The culprits are the distributors that take the raw material and do the finishing work. The NASA handbook identifies two kinds of titanium cheaters. Some take raw titanium plate and forge the finished component even though the specification calls for using a more complex rolling process. Others cheat by simply cutting down a raw titanium billet into the final shape, rather than using a forging or rolling process as required in the contract.

Both forms of cheating result in a metal that superficially looks right, but lacks the minimum strength or fatigue characteristics demanded by the aircraft’s designer.

The latest P&W lawsuit shows that defence contractors are still vulnerable to the problem, despite all of the government’s efforts over the past five years to identify the cheaters.

It also comes at a time when concern grows about access to Russian stocks of titanium, and the possibility that US commercial aircraft will have to depend on Western sources of supply.

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Source: Flight International