Slight bit of rust on the barrel fins

[piperboy84]

Need a bit of advice, doing some routine fixing of the plane and have a light rust covering part of the barrel fins and also have the paint rubbed of where the baffeling meets the fins, I have ordered lycoming grey engine paint and plan on giving the fins a rub down and repaint on an as needed basis,do I use any kind of primer or prep prior to painting on the lycoming grey?

[Crash one]

I asked someone that, can't remember who, either engineer or paint manufacturer, but no it's a single coat job.

[A and C]

To do the job properly you need a primer and top coat, these are best applied with the cylinder off the engine and heated in an oven after painting to fully cure the paint.

There is also a Lycoming SB on the subject of the effect of paint on the nuts holding done the cylinder.

[mad_jock]

Piper he doesn't mean a microwave when he says oven BTW :p

[Saab Dastard]

heated in an oven after painting to fully cure the paint.

As a matter of curiosity, would an oven heat the head higher than normal running temperature? Or perhaps more evenly?

SD

[A and C]

You are looking for an even and controlled curing of the paint, a working cylinder by its very nature is not at an even heat.

[Echo Romeo]

A and C, what type of primer would you use? LAS list engine paint but no high temp primer so far as I can see.

[M-ONGO]

Humbrol or airfix works well.

Scale Plastic Model Kits by Airfix - 31 Slate Grey Matt - 14ml Enamel Paint (http://www.airfix.com/shop/humbrol/paints/enamel-paints/aa0343-31-slate-grey-matt-14ml-enamel-paint/)

Or for a realistic club training aircraft look;

Humbrol Weathering Powder: Dried Mud, Dust & Rust (http://www.airfix.com/support/top-tips-and-advice/humbrol-weathering-powder-product-videos/humbrol-weathering-powder-dried-mud-dust-and-rust/)

[A and C]

If I remember correctly ( I am away from the hangar for a few days and can't check ) we use a very light dusting of a standard etch primer.

No paint mist go under the cylinder nuts so after assembly we touch in this area with a small brush, this is not ideal but better than having the cylinder nuts come off !

[cockney steve]

interesting point, a&c aiui the base nuts are a relatively low torque and no loctite or locking wire......seems crazy to me, especially when one hears that a jug coming loose is a not uncommon occurence :eek: I know of a 172 donk that lost one at less than 20 hours, from a fully rebuilt donk pilot=owner less than impressed.

WRT paint, surely the less , the better ? I would imagine it has a marginal insulating effect , which arguably helps even up temp. variations....but hey, it protects a cold surface from condensation and surface rust....in the due course of time , i'd expect any paint to bake on then, as years pass, to dry out, oxidise, shrink, crack, peel.....generally the item is scrapped before this point is reached.

Agreed an ideal refinishing would involve proper stripping , surface prep and spraying (not good with fins ) or dipping/centrifuging followed by stoving.....but it's just a lycosaurus aero-engine and i suspect the paint is primarily cosmetic...(otherwise it would be matt black)

just my take on it...standing by for incoming

[A and C]

I suspect the cylinders coming off was due to the SB about the paint NOT being complied with rather than the torque loading on the nuts.

I have ( in thirty years ) yet to see a properly fitted Lycoming cylinder come adrift, I would say that the load on the cylinder through studs increases a lot as the engine expands with heat and the relitivly low torque load turns into a substantial force when the engine reaches working temp.

[jxk]

On some engines I've seen the use of 'single thread hex nuts' are used as lock nuts for the base cylinder nuts. I don't know how effective they are!

See here: http://www.trinitylogisticsgroup.com/documents/nuts/single_thread_hex_nuts.pdf

Most of the new engines I've seen do not seem to have any primer and are painted just like you would use Hammerite ie one coat.