Seat rails for a 79 M20J

[201Steve]

1 hour ago, A64Pilot said:

On edit, think of it this way, gummed / carboned up rings is NOT normal for a healthy cylinder,

 

1 hour ago, A64Pilot said:

My primary concern with a ring flush is that nothing is done to investigate and correct whatever is causing the rings to stick

I think the likely answer is TEL

[A64Pilot]

You think lead is fouling rings? So why isn’t there a procedure to remove this lead fouling? Why don’t we all suffer from lead fouled rings? 

Lead’s not fouling rings, for decades we ran fuel with a LOT more lead, remember we burn LL now, low lead, when I was a kid there was so much lead in Avgas that if it got on your hand, it would turn your hand white when it dried.

Why has no engine manufacturer published a procedure to free up stuck rings? 

Only thing that gums up or sticks rings in a engine that’s regularly flow is carbon, from excessive blow by. In an engine that's sat for extended periods, rust can stick rings, and actually this “ring flush” is what’s been done in boat motors that have seized rings from either water ingestion usually though the exhaust elbow, or just from a long period of inactivity, all kinds of things are recommended, but usually Diesel fuel, MMO or ATF is used, been done since probably boats have had motors.

Sticking rings or gummed up rings is NOT a normal operating condition, if it were then we would have inspection intervals and some form of corrective action for it, like we inspect plugs or magnetos etc.

I’m not going to convince you and that’s fine, but I hope someone that’s wondering if they should or shouldn’t might just consider investigating what caused the rings to stick before doing this flush thing.

If you can come up with what caused them to stick and change whatever that is, then fine, but I feel real certain that’s it’s excessive oil and just cleaning it out won’t fix anything, you need to address the cause.

Many times especially on infrequently flown engines the cause is polished bores, meaning the engine sits until a layer of corrosion is formed on the cylinder walls, the engine is run, the rust is almost instantly cleaned off, engine sits, repeat, before too many hours the cross hatching on the cylinder is gone, this means the layer of oil normally on a cylinder wall isn’t there, and wear is greatly accelerated but if it’s addressed quickly all that’s needed is to pull the cylinders and have the honed and measured and most of the time your still within limits, fit new rings and your fine.

Some symptoms are low compression from stuck rings, from blow by, oil turns black very quickly, again from blow by and oil temps are high. from you guessed it blow by, its hot and heats the oil. If you keep nursing the engine, wear is excessive and when your finally forced to do something about it, wear is beyond limits.

Neighbor right beside me finally pulled the cylinders on his A-65 and had them honed, his Baby Ace has flown very little in years.

Neighbor behind me has a C-182 with a relatively “new” engine, it’s flown 100 or so hours in 20 years since major, he’s nursing it, has lapped an exhaust valve or two, but really should pull the jugs and have them honed and measured, honing takes very little metal off, a light honing can’t really even be measured it’s so slight.

You can easily see polished bores even with a inexpensive borescope.

[Martin S.]

Evening gents,

Heard rumors that on certain Cessna models its possible to mount new seat rails with screws and nuts instead of rivets. Anybody an idea whether this would be legal on a Mooney? Seems to be a rather convenient way of reducing the installation effort.

 

Regards,

Martin

[Guest]

Most of the rivets used to hold Mooney seat rails on are 1/8” diameter.  The smallest diameter of structural screw is 5/32”.  You’ll be drilling the holes larger in everything and adding un wanted weight to the airframe.  

Clarence

[Martin S.]

On 6/1/2022 at 12:16 AM, M20Doc said:

Most of the rivets used to hold Mooney seat rails on are 1/8” diameter.  The smallest diameter of structural screw is 5/32”.  You’ll be drilling the holes larger in everything and adding un wanted weight to the airframe.  

Clarence

Clarence, good thoughts, especially with the screw diameter. Thank you!