I have been consistently smelling fresh avgas while executing a missed approach at full power. Our fuel flow is also well above redline at takeoff power...Usually around 38gph and up to 39 at times. Would love some guidance.
Top shaft seal on the fuel selector is the likely culprit. At full RPM, the pump is really spinning it up, so there is a bunch of fuel in the return system under pressure; the seal I discuss is what is supposed to hold it back. The fuel selectors are a 10-year recommended overhaul item.
Mike ABS Technical Advisor
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11/10/2023 - 9 months ago
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Top shaft seal on the fuel selector is the likely culprit. At full RPM, the pump is really spinning it up, so there is a bunch of fuel in the return system under pressure; the seal I discuss is what is supposed to hold it back. The fuel selectors are a 10-year recommended overhaul item.
Follow up...my mechanic noticed fuel stains beneath the fuel pump. We did a leak check with throttle idle, mixture idle cutoff and aux pump Hi. A solid trickle of fuel leaked out from the fuel pump. My mechanic is recommending an overhaul or exchange of the fuel pump. It was last overhauled in 2006 with the engine. I am thankful for Beech's design to have the cabin air shroud around that crossover exhaust pipe to help cool that exhaust pipe down. I imagine a lot more fuel was dumping out of that leak at full takeoff power during a missed approach.