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Posted

Here is a video of what I found today. Taken with the high boost on. Saw some blue streaks on my cowl flap and investigated while I was changing my oil.

It was hard to see until I pulled off the guard below the baffle. Sadly it seems you can't just replace the diaphragm, but this will be a new check I do every oil change and I encourage y'all to do the same. I feel pretty lucky it never caught fire, I suspect it's been going on for some time.

 

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Posted

I had somebody walking by while I was getting ready to start... they waved at me to advise me that my electric fuel pump was draining avgas on the ground...

The pump’s drain does a nice job of making it hard to know...

My electric pump got OH’d as the next step... I didn’t think through that part fast enough... the electric pump gets used during full power ops....  so it is pouring fuel automatically during T/O and climb with an IO550... the M20K fuel system is even more complex...

great PSA!

I livened up the link a bit more... :)

Best regards,

-a-

 

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Posted

OH SHIT!  That is NOT GOOD!  I had fuel shooting sideways under cowl from a damaged gasket on flow divider.  Maintenance and keeping and eye under the cowl are SO IMPORTANT.  Great catch here.  That is a LOT OF FUEL Leaking.  Missile’s are HOT under the cowl.  Watching that made me get a serious pucker...

PSA received.  PSA will be followed.

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Posted

That’s the engine driven fuel pump and it appears to be leaking from the mixture control shaft.

Clarence

Posted

Looks like a mold parting line... accented by the blue pigment from 100LL drying in it...

Definitely something to look closer at in case a crack decided to form on the molding line.

PP thoughts only...

Best regards,

-a-

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Posted

Thanks everyone. In case it wasn't clear, part was removed and shipped off for overhaul. Unsure if related, but behavior seems to have started after shortly performing CSB19-01A. 1400 TTSN&SMOH in 20 years.

Some context here, I took the video with throttle and mixture full forward (priming configuration) so I suspect it wasn't leaking as badly with the prop spinning.

Part is out of my hands so I don't have a better picture unfortunately, but violet circle are mold lines. I can't take it apart fully to be certain, but I agree with @M20Doc it's the mixture control arm in the orange circle.

 

pump_zoomed.thumb.png.03f054ef3de04f06a4ee136b50a7d659.png

pump.png

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Posted

Wow, that's a huge leak!!

Glad you found it on the ground :) it needs to go to your favorite fuel system specialist repair station asap! They run about 1 AMU to OH, at 20 years it will probably need one but starting with an inspection will get you an estimate of what it needs.

This shouldn't be at all related to CSB19-01A since it replaced a hose for metered fuel between throttle body to fuel divider - nothing to the fuel pump.

Also It looks like the pump has already complied with an earlier SB to replace the brass arm with a steel one - so you look good there. (The brass one would wear and all of a sudden you don't have a mixture control!)

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