The Cessna 120-140 Association Forum

Hello,

I am doing an exhaustive inspection of the compliance status of my airplane maintenance against the published ADs. Little by little and with a lot of patience.

I found that after a general overhaul of my carburettor in 2017, the mixture and the throttle controls are fixed with bolts and nylon locking nuts, then the shop paints with CrossCheck orange paint. But they did not install the castellated nuts.

Thanks to John Kliewer for the kindness, work and help with my carb !

I remember that an AD claims for drilled bolts plus castellated and pinned nuts, for other planes of the Cessna family: I also fly 150 and 172s that have that linkage.

I started reading the FAA and found AD 86-24-07 that claims that. But the AD lists many Cessnas, from 150 to 210, but not our little birds.

When I read SL number SE79-6 I see that Cessna in 1979 recommended the castellated nuts and cotter pins for every cessna build before 1979.

Thanks for any advice !
And nice Sunday

Horacio, I believe it's the same for our "100 series" planes. And, although I'm recently told by a respected engine shop that "elastic nuts" are acceptable now for attaching the oil sump, the old "rule" of no elastic stop nuts firewall forward that I've heard for years still seems to make sense. (RE the oil sump, I believe the superseded studs are actually not drilled, but there are still "better" all steel nuts that can be used. ...but, I digress (detour)). Due to the movement of controls that are attached with bolts I'm confident that the best ("correct") practice is to utilize castle nuts with pins. Someone with exact pertinent knowledge will likely be along to confirm or, at least, explain much better than I have. It sure sounds like you're tweaking your plane to ensure airworthiness, safety and "correctness" -- all very important. Mac

2066 wrote: ↑Mon Feb 22, 2021 10:18 pm The old "rule" of no elastic stop nuts firewall forward that I've heard for years still seems to make sense.

Thanks Mac for sharing your opinion. That kind of information is what I was looking for. I will replace all nuts firewall forward. Period.
I was a bit confused because the AD does start with C150 and then goes up to many Cessnas ...
Perhaps FAA just forgot to include our little and great planes. I see no reason to ask for castellated nuts in C150 carb and not in ours. When, in many cases the carbs and engines are identical or quasi.
Monday morning AD ?

Have a very nice day !

Here's another opinion...

1.) You should not use stop nuts with nylon (e.g. MS 21044) forward of the firewall, but, there are all metal stop nuts (e.g. MS 21045) that are perfectly acceptable.

2.) Connections where there is the potential for rotation between the surface the nut face bears on and the shank of the fastener should employ a positive locking device, like a cotter pin or safety wire.

6643 wrote: ↑Tue Feb 23, 2021 8:06 am Here's another opinion...

1.) You should not use stop nuts with nylon (e.g. MS 21044) forward of the firewall, but, there are all metal stop nuts (e.g. MS 21045) that are perfectly acceptable.

2.) Connections where there is the potential for rotation between the surface the nut face bears on and the shank of the fastener should employ a positive locking device, like a cotter pin or safety wire.

Thanks for clarifying, John. No...yours is fact. Mine was opinion . ...unrelated to Horacio's question, I continue to be curious about the OH manual specifying "Nut, Elastic Stop" for securing the oil sump. I use the all metal stop nuts...just because it makes sense to me & my IA agrees. The manual page I have is dated March 1977, so it isn't new, but I'd never seen elastic stop nuts used "anywhere" FWF until my most recent major OH. ...not a biggie, certainly, but just curious. Mac

The nuts carry a Continental part number. If you order one, I'm guessing it is all metal. Personally, for the sump I prefer MS21042-4 nuts. They're all metal stop nuts and have a reduced size hex for easier installation in tight quarters.

6643 wrote: ↑Tue Feb 23, 2021 1:27 pm The nuts carry a Continental part number. If you order one, I'm guessing it is all metal. Personally, for the sump I prefer MS21042-4 nuts. They're all metal stop nuts and have a reduced size hex for easier installation in tight quarters.

Fresno shows the Continental part # (22661) that appears to be the same as the MS21044. In fact I'd ordered and used the MS21042-4 for a recent sump R & R based on your related posts. They are easier to install and it just "feels" better not to have "nylon" nuts up there. Again, my IA agrees. On a somewhat related note, I used a REAL (silicone) gasket for the first time for the sump and, so far, no runs, no drips and no leaks. I'd used the REAL rocker covers with great results and sure am pleased with the sump...so far. Mac