Missing rivet head in snorkel

[RV7A Flyer]

It has been a long time since I cleaned my air filter (I know, poor maintenance practice, but never really gets dirty, so it did slip by me for far too long), so given the crappy weather, I pulled it out to clean it today. Horizontal induction fuel injection, so I have the "snorkel".

To my horror, I see on of the flush-head rivets that holds the inboard side bracket in place (sorry, don't have the drawings handy, but those with horizontal FI will know what I'm talking about) is missing the flush head. That can only mean it popped off and went into the snorkel. I searched the snorkel well (in case it had *just* happened), then borescoped the entire air path into the servo, finding nothing. Vacuumed the whole thing out and searched through the canister on the shop vac, didn't find anything. That means it's likely it went through the engine...

Pulled the plugs and borescoped all cylinders...no sign of any damage to pistons, cylinder walls, valves or plugs. Looks just like it did at the last annual.

I've gone through at least 3 oil changes w/ oil analysis since the last filter cleaning (i.e., last time I inspected those rivets), all are near-perfect. Compression check at last annual was outstanding, but I might do it again now a few months prior to annual.

Anything else I should check SHORT OF PULLING PARTS OFF THE ENGINE? I'm sure someone here is going to suggest that I do a complete teardown, or start pulling jugs and such. I'm not going to do that, since the engine hasn't shown a lick of a problem, no indications of detonation in the data logs (every flight uploaded to Savvy and reviewed at some point, plus I pay for their automated analysis), etc.

I'm looking for any additional NON-INVASIVE things to check before assuming the small piece just passed on through the engine.

Again, a VERY thorough look in each cylinder showed, as far as I can see, no damage or remnant parts.

Any suggestions/comments are very welcome...TIA!

Oh, and I'll be putting a thin layer of proseal over all of these rivets, just as I did with the ones on the alternate air door flange...I didn't do that originally as the plans didn't call for it

[terrye]

Sometimes something as small as a rivet head will go right through a cylinder without causing any damage. As long as the plug electrodes don't show any marks, and you can't find any marks on the piston, cylinder head or valve seats, I think I'd keep flying it. And keep on inspecting it regularly.

No, a complete teardown is not indicated.

[lr172]

If it made it in, not likely to do any damage. It would likely spend some time getting smashed by the opening/closing intake valve. No damage potential here. Steel valve/seat with small aluminum piece-non-issuje. Once small enough to pass the valve clearance, It would spend some time bouncing around the cylinder. Again, a small aluminum piece bouncing around would do real damage here; It simply doesn't have enough mass to hurt anything. Eventually it either disintegrates from all the banging around or it slips out past the exhaust valve.

This event wouldn't convern me. A metal screw head, on the other hand would.

Larry

[skylor]

Originally Posted by RV7A Flyer

It has been a long time since I cleaned my air filter (I know, poor maintenance practice, but never really gets dirty, so it did slip by me for far too long), so given the crappy weather, I pulled it out to clean it today. Horizontal induction fuel injection, so I have the "snorkel".

To my horror, I see on of the flush-head rivets that holds the inboard side bracket in place (sorry, don't have the drawings handy, but those with horizontal FI will know what I'm talking about) is missing the flush head. That can only mean it popped off and went into the snorkel. I searched the snorkel well (in case it had *just* happened), then borescoped the entire air path into the servo, finding nothing. Vacuumed the whole thing out and searched through the canister on the shop vac, didn't find anything. That means it's likely it went through the engine...

Pulled the plugs and borescoped all cylinders...no sign of any damage to pistons, cylinder walls, valves or plugs. Looks just like it did at the last annual.

I've gone through at least 3 oil changes w/ oil analysis since the last filter cleaning (i.e., last time I inspected those rivets), all are near-perfect. Compression check at last annual was outstanding, but I might do it again now a few months prior to annual.

Anything else I should check SHORT OF PULLING PARTS OFF THE ENGINE? I'm sure someone here is going to suggest that I do a complete teardown, or start pulling jugs and such. I'm not going to do that, since the engine hasn't shown a lick of a problem, no indications of detonation in the data logs (every flight uploaded to Savvy and reviewed at some point, plus I pay for their automated analysis), etc.

I'm looking for any additional NON-INVASIVE things to check before assuming the small piece just passed on through the engine.

Again, a VERY thorough look in each cylinder showed, as far as I can see, no damage or remnant parts.

Any suggestions/comments are very welcome...TIA!

Oh, and I'll be putting a thin layer of proseal over all of these rivets, just as I did with the ones on the alternate air door flange...I didn't do that originally as the plans didn't call for it

Have you pulled the servo or an intake tube to be sure you?re getting a good look at the floor of the intake plenum? It could be laying in there somewhere.

Skylor

[rv8ch]

When I reviewed the RV-14 plans I saw that they did the whole snorkel with glass. I figured that there must be a reason for that. I covered all the rivets with a couple of layers of glass.

You are moving the volume of a swimming pool of air through the engine every 10 minutes, so as the others have said, if no visible damage, fly on.