Is going past TBO more expensive? Plus fuel vents and turbocharger temps. Email [email protected] for a chance to get on the show.Join the world's largest aviation community at aopa.org/joinFull episode notes below: Mike wonders if running past TBO actually costs more. He hasa Mooney and has heard that overhauls far beyond TBO can cost more as a resultof having to replace more parts. That is an oft-reported myth, Mike says. Theonly things that can cause an up charge on most field overhauls are having toreplace the case or the crankshaft. Otherwise it’s a fixed price. Paul says thetop engine generally goes into the trash. On the crankshaft, they usually justhave to polish it or grind it. There’s no repairing a crankshaft. If it’s bad,it was bad because it had some other type of problem. You can go thousands ofhours on crankshafts. Mike said Lycoming had a white paper on their websitethat said crankshafts are generally good for 14,000 hours. Cracks on the case canbe welded.  Mark has an early 182 and he’s having issues with the fuelcaps properly venting. He has noticed that once you fill the tanks with coldfuel, there doesn’t appear to be an outflow vent. Paul said there’s a smallweep hole that allows the expanded fuel to vent. But Mark’s tanks still aren’tventing. He pulled it out but didn’t seem to find a weep hole. He said it looksoriginal and has an early Cessna part number. If the fuel is pouring out itneeds to be replaced because the check valve is bad. The wing will balloon andcan cause structural damage without a weep hole. He said when he removes thecap a big woosh of air will come out, indicating the fuel isn’t venting out asit expands.  Jim is wondering how TIT and EGT intersect. He flies a turboSaratoga and has been experimenting lean of peak and rich of peak. He’s noticeda significant difference between EGT and TIT. If the TIT is farther away fromthe engine, he’s wondering why it’s hotter than EGT. He’s also wondering howhot he can let the turbocharger get. Mike said TIT is hotter because the EGTprobe is only seeing gas flow for less than a third of the time, and only whenthe exhaust valve is open. The EGT probe actually measures a “probe”temperature that averages the temps over time. When the gas gets to the TITprobe it’s a constant heat from all cylinders all the time. Redline on his TITis 1,650 degrees, which Mike said is a continuous operation limit. Paul askedwhat the exhaust system is made of because that matters. He suggests notexceeding the red line. In cruise, the lower you can keep the TITs, the longerthe system will last. Mike limits his TIT to 1,600.