AL-31F is only 4000hrs.10000+ hours? The lifespan of WS-10H is on par with Russian AL-31F.
Nothing to do with MTBO but rather the cost and disruptive effect if switch to Chinese engine for JF-17.Otherwise PAF would have been turning cartwheels and replacing the RD series with the WS13 series. The current MTBO is less than RD series. However, it is logical to assume you have achieved 60-80 % reliability and MTBO to warrant change of engines. The moment your reliability and engine life approaches RD series you will have PAF switching over to WS13.
Pakistan to stick with RD-93 engine for JF-17, say PAF officials | IHS Jane's 360 Air Platforms Pakistan to stick with RD-93 engine for JF-17, say PAF officials Reuben F Johnson, Dubai - IHS Jane's Defence Weekly 18 November 2015 A Pakistan Air Force JF-17 Thunder making the type's first...
"What does this tell you?" asked one programme officer rhetorically. "If the situation was as it has been portrayed at times - that we are just utilising the RD-93 as a temporary solution until the Chinese can 'save' us with their own new engine - then we would not be expending the resources to set up this overhaul base. For us, changing to another engine would not make any sense and would be disruptive and cause a huge expense for the JF-17 programme."