FYI PSA: Check your rocker box cover screw torque

[Neal]

I had a little booboo where I hit one of the rocker box covers with my engine lift and dented it. It's purely cosmetic yet my ego is severely bruised. Another one is on the way from CubCrafters, it's not a big deal. This is the part of the engine that's at the head of the cylinders with the black "CubCrafters" and "cc363i" name plates glued on. CubCrafters paints the rocker box covers after grinding down the "Lycoming" that comes on it so it is taking some processing time but I'll have it early this week thankfully.

So today I started cleaning out the orange RTV sealant to be able to swap out the rocker box covers and figure out a game plan with the baffle, etc. I put a screwdriver on the bottom rocker box screws which have the baffle in between the screw head and rocker box and was surprised many of these were loose and very easy to unscrew with minimal effort. I recently read the attached instruction manual from Lycoming on the rocker box covers and know the torque should be around 30 in-lbs. So I took my torque wrench around to check torque and most of these bottom screws were only around 15 in-lbs, the top ones which did not have the baffle between them were tight. So I suggest people check your rocker box cover torques. Something I would have never touched if it wasn't for this incident.

I believe silicone gaskets are in use, it's the newer style gasket, but I'll know for sure when I get the parts from CubCrafters. I did order 2 x silicone gaskets from Aircraft Spruce just in case...yeah, I'm a parts hoarder, I know.

Check your torques.

OHHH - during the process of picking out the RTV I bumped one of the black name plates on the rocker box cover and it fell off. I know CubCrafters just epoxies these on with a special epoxy but wow, that was barely holding on. Ironic... so do not touch those black name plates, consider them fragile!!!

 

[Cactus Charlie]

Standard practice at every annual to put a screwdriver on these screws and check they are snug. Probably less of an issue with the newer silicone rubber gaskets than the older cork gaskets.

Did you see my post on the CubCrafters forum about my dearly departed "CubCrafters" name plate and my dented pushrod shroud tube?

I would far rather have an unpainted engine without the crap stick on labels. My last one in that configuration ran over 3,000 hours and is still flying with the new owner.

 

[Neal]

Yeah, saw your post. I had another friend in a new FX-3 with one that fell off too. They should just stop putting that nonsense on.

 

[Neal]

I've had a curious trace of oil show up on the forward most, top most screw hole when removing the right side gill/vent/louvre (whatever the name of this panel is). It's odd how oil drips from that hole and I have no idea where it's coming from. I suspected a slip joint but I have no visual indicators on the inside of the cowl like I've seen on other FX-3's with slip joint problems (black stains). With learning about these rocker box cover plates and finding the lower screws loose, I think I may have discovered the source of the oil. I'll have to check for any other traces but don't recall seeing anything. It will be interesting after re-torquing these screws if this oil situation goes away.

I don't think it's a great design by CubCrafters to be using these rocker box cover bolts to secure the baffle. They have two washers between the baffle and the engine side. Nothing spells out a secure fit in this situation. I'd rather they just use the RTV to hold the baffle or glue/weld some other bracket to something for the baffle to screw into.

 

[Neal]

@Cactus Charlie do you ever check the bolts on the manifolds (I think it's called)? I don't see any leaks, nor have I with the rocker box screws, but I always wonder if they should be checked as well?

 

[Cactus Charlie]

I think it is good practice to check the intake flange bolts and the exhaust flange nuts for presence and security at every inspection. Some are hard to reach on the CC363i and may require 1/4 inch drive socket and universal joint. Be careful not to damage the induction tubes.

I apply a light torque to confirm they are not loose. I don't want to break them free. I never found any missing or loose on my CC363i but I did on my O-360.

 

[Cactus Charlie]

I pulled both left side rocker boxes on my CC363i and found the screws had been run down so tight at the factory that the silicone rubber gaskets had been squeezed to destruction. Something else to be replaced before my FX-3 gets signed off as airworthy.

Torques applicable to cork gaskets DO NOT apply to silicone rubber gaskets! Perhaps another example of torque wrench taking priority over experience.

 

[Neal]

I believe the attachment I posted in the OP has values for the new gaskets? Haven’t checked.

I think the design of having these bolts go through the baffle is a terrible idea. I can free spin a lock washer behind the bolt but can’t tighten the bolt. No way these bolts will remain secure with the baffle in between. However I’m not sure the rocker boxes require much to remain sealed. I don’t believe they are under any pressure.