Winter operations / lowest temperature for starting / preheating methods (merged)

Antonio wrote:

it is not a good idea to run it unless you are actually going to start the engine

Capitaine wrote:

Thanks Antonio: I’d never heard of this before. Is it because of condensation when the engine cools down again?

Yes, as @Raven and @gallois above pointed out. If kept at constant temp, then it should not be a problem, but the temp cycle will cause condensation on all exposed parts inside the engine.

There other factor applies for infrequent use. When the engine is not running we like to keep all internals covered in oil. That is why multivis oils dont protect as well for low utilization:

Multi-grade: low-viscosity at low temps will facilitate drain-back into the sump in a shorter timeframe
Single-grade : high viscosity at low temps will maintain internals coated for a longer period. Of course this will cause problems for starting at low-temps if not preheating, hence your engine manual recommends different grades depending on ambient temp. THis is relevant for private use and thus there are multiple reputable online sources (including Ed Kollin, of course he sells the stuff, and Mike Busch) recommending W100+camguard year-round for all Lycosauruses if you can perform preheat for all cold starts<5C.

Of course if the engine is in a club or school environment where it is used on a daily basis, the oil drain back is no factor.

Peter wrote:

Terbang’s experience is not at all surprising.

Heating the six pots individually is just a marketing exercise, to say “Hey we do it properly”. It is BS. The engine is a ~200kg lump, with the outside highly thermally conductive (aluminium) and there is no need to heat it in many places. As I wrote further back (I merged two identical threads) you just need to heat the sump.

Of course the most important is heating the oil pan: no question there.

As to the cylinders…well. If cyl walls are warm, then clearances and lubes are supposed to be immediately better on start diminishing wear. How much? Difficult to tell, since clearances are anyway high on Lycosauruses. Perhaps more relevant for Rotaxes as @LeSving sais?

There are two religions, if I may call it that: Reiff and Tanis.

Reiff uses cylinder-base heaters. Of course the cylinder head sensor will not read much…there is a lot of aluminum mass at the head and a thin, finned, steel cylinder wall carrying that heat towards the head. MOst of the temp increase will be on the bottom side of the cylinders, not the head.

Tanis uses heaters on the CHT probe wells on the head on Lycosauruses, so there is some compatibility to be dealt with with CHT sensors. @LeSving can tell us about its installation on Rotax heads. THis surely heats the aluminium head much better than the Reiff system, not so much the steel cylinder barrel.

Which of the two (head or barrel heating) is more important for low wear on a cold start?

Antonio wrote:

Reiff uses cylinder-base heaters. Of course the cylinder head sensor will not read much…there is a lot of aluminum mass at the head and a thin, finned, steel cylinder wall carrying that heat towards the head. MOst of the temp increase will be on the bottom side of the cylinders, not the head

I would have expected that as well, but my observation is to the contrary. At least after a couple of hours temperature of the whole engine including the heads has evened out. Oil as well as CHTs (and EGTs) read around 90F.

Peter wrote:

Attaching something to the sump would need an STC for drilling holes in the sump.

These systems are STCed. However, the elements heating the oil sump are bonded with hight temp epoxy. You have to follow the IM but then it works without issue.

Peter wrote:

Attaching something to the sump would need an STC for drilling holes in the sump. Also (not sure) is the sump directly removable, without affecting the accessory gearbox housing?

No, you glue it to the sump! The only real drawback is that is has to be removed when the engine is sent for overhaul and that is nigh impossible to do without damaging the heater.

Also, no STC is needed. Standard change CS-SC204b applies. (You don’t need a Form 1 either!)

The Standard Change doesn’t actually preclude drilling holes. It says “The consideration with respect to the safety of flight is that the preheating system neither interferes with functional equipment nor comes loose or detached and creates some other flight hazard.”

Airborne_Again wrote:

Also, no STC is needed. Standard change CS-SC204b applies. (You don’t need a Form 1 either!)

This is EASA only.

terbang wrote:

This is EASA only.

Yes, but I thought installing heaters on N-reg would be dead simple? No need for Form 1’s etc. etc.

It’s not that bad under FAA either:

Both Tanis and Reiff have PMA approvals for their parts.
For reasons UNK Tanis for 6-cyl Lycosauruses are STC approved.
All others Tanis and Reiff are minor-mod approved and Reiff even has an FAA letter confirming. As such a log entry by an A&P is all that is required for approval on FAA aircraft.

terbang wrote:

after a couple of hours temperature of the whole engine including the heads has evened out

Yes, that was even with some failed cyl heaters, right? From your observation obviously after a couple of hours inside a hangar and with an enclosed cowling it all evens out.