In order to control the leaning range and obtain the convenient safety leaning threshold for engineering practice based on the case of a large number of exhaust valve ablations caused by excessive leaning in the operation of a certain aero piston engine
the corresponding relationship between valve operating temperature and exhaust gas temperature (EGT) at this engine was obtained by measuring the actual operating temperature of exhaust valve body near the sealing surface
and the engineering problem of indirectly measuring the actual operating temperature of valve body with EGT as parameter was solved. With the corresponding relation and by ensuring that the protective layer on the exhaust valve sealing surface was not damaged
the safety leaning threshold with 732℃ of EGT at this engine was obtained
and the reliability of this threshold was proved by practical test of 70000 flight hours.