The problems, some of them identified in government audit, revolve around poor project management. The work and material for the F-35 aircraft as well as the engine are hugely outsourced.
The U.S. Government has halted accepting delivery of engines until the titanium sourcing issue can be resolved. Adding on to that, deliveries will also not be accepted until the true cause of the engine fire that destroyed an F-35 can be actioned to the satisfaction of the U.S. Government.
"Delivery of engines was halted in May after an in-house inspection and testing process 'raised questions about the origin' of the titanium"
Statements from Pratt and Whitney and the F-35 program office claim these problems are fixable and are being worked.
One of my unnamed sources, an independent engineer with years of experience in defense analysis, stated that China is the biggest supplier of titanium but what is being produced is "low grade crap". The best stocks of titanium comes from Russia and the Ukraine. Most of the Russian titanium is made out of Ukrainian raw materials. The source also states that the U.S. should simply buy all of its titanium from Ukraine, concluding: why they buy from Russia and China is not clear.
A former U.S. DOD defense analyst Pierre Sprey stated in an email:
Can you believe the incorporation of fraudulent titanium into the F-35 engine has been completely covered up since May? P&W hasn't delivered a single engine since May and neither the JSF program nor OSD said boo--obviously waiting for all four Congressional defense committees to rubber stamp the F-35's FY 15 budget before trying to slip this bombshell past the media and the public on Labor Day weekend.
A history of F-35 engine problems can be read here.
-Time's Battleland - 5 Part series on F-35 procurement - 2013
-Summary of Air Power Australia F-35 points
-Bill Sweetman, Aviation Week and the F-35
-U.S. Government Accounting Office (GAO) F-35 reports
-F-35 JSF: Cold War Anachronism Without a Mission
-History of F-35 Production Cuts
-Looking at the three Japan contenders (maneuverability)
-How the Canadian DND misleads the public about the F-35
-Value of STOVL F-35B over-hyped
-Cuckoo in the nest--U.S. DOD DOT&E F-35 report is out
-6 Feb 2012 Letter from SASC to DOD boss Panetta questioning the decision to lift probation on the F-35B STOVL.
-USAFs F-35 procurement plan is not believable
-December 2011 Australia/Canada Brief
-F-35 Key Performance Perimeters (KPP) and Feb 2012 CRS report
-F-35 DOD Select Acquisition Report (SAR) FY2012
-Release of F-35 2012 test report card shows continued waste on a dud program
-Australian Defence answers serious F-35 project concerns with "so what?"
-Land of the Lost (production cut history update March 2013)
-Outgoing LM F-35 program boss admits to flawed weight assumptions (March 2013)
-A look at the F-35 program's astro-turfing
-F-35 and F-16 cost per flying hour
-Is this aircraft worth over $51B of USMC tac-air funding?
-Combat radius and altitude, A model
-F-35A, noise abatement and airfields and the USAF
-Deceptive marketing practice: F-35 blocks
-The concurrency fraud
-The dung beetle's "it's known" lie
-F-35's air-to-air ability limited
-F-35 Blocks--2006 and today
-The F-35B design is leaking fuel
-ADF's wacky F-35 assumptions
-Gauging performance, the 2008 F-35, Davis dream brief
-Aboriginal brought out as a prop
-Super Kendall's F-35 problem
-LM sales force in pre-Internet era
-History of F-35 engine problems