Sometimes proverbial smoke leads to fire. And in other cases, there can be far less to a story than some might infer.
Such is the case of “screech” in which certain pressure pulsations occur when operating in full afterburner mode. This phenomenon is not new to military aviation and therefore not unique to Pratt & Whitney’s F135 engine for the F-35 Joint Strike Fighter, although it was inaccurately reported as a “new” problem by the Air Force Times this week.
Nonetheless, Pratt & Whitney discovered screech around May 2009 during development testing at low altitude and high speed. It has already been addressed with minor hardware and software modifications that eliminate the issue. In fact, design of this fix benefitted directly from tools and processes developed for our F119, the only engine to power the F-22. Together, the F119 and F135 are the only two production engines to provide augmented stealth capability, particularly noteworthy at a time when would-be stealth aircraft elsewhere in the world have garnered a disproportionate amount of media attention.
Now that the modifications have been identified and implemented, the F135 provides maximum thrust throughout the flight envelope. Modified test aircraft have shown excellent results, while the production configuration is being validated this year for both the F135 Conventional Take-Off and Landing / Carrier Variant (CTOL/CV) and Short Take-Off and Vertical Landing (STOVL) model. After all, full thrust throughout the flight envelope was a prerequisite for the government granting Initial Service Release for the CTOL/CV engine in March 2010, followed by the STOVL one in December 2010. No other fifth generation propulsion system has even come close to certification, let alone production.
Therefore, a mention about screech contained in an annual report from the Pentagon’s Office of the Director, Operational Test & Evaluation hardly qualifies as breaking news or even news. We now return you to your regularly scheduled programming already in progress.