Light Aircraft Association

I have a Rotax 582 blue top which according to my maintenance schedule will soon need to be completely stripped down and re built, when it actually is still in good condition and running OK.
I note that the SA CAA have OKed a revised Schedule as enclosed. does anyone have experience of finding any major faults on a 300Hr 582 which has been run on fuels and oils as recommended by Rotax, (Ie semi synthetic).
The recommendations seem to me to be far better measured than the standard Rotax schedule, which I presume is set to cope with all sorts of uses and conditions, where as ours run at a more constant speed and probable for less time at full throttle and a greater proportion of its life its running away from dust and ground crudd.
(Sorry I cant work out how to attach a file so the SA schedule may not come out) please try this link
http://www.aviation-engines.co.za/downl ... hedule.pdf

Any thoughts please and how do I go about getting the revised schedule adopted?

Roger

As Inspectors we sign a declaration at each renewal inspection that states we have inspected in accordance with required inspections, Mandatory Permit Directives and procedures promulagated in SPARS.

In SPARS it states Two stroke engines should be maintained iaw the Rotax "Maintenance Plan" reference 3 UL 91-E which is what you refer to in your post.

Whilst your engine may sound happy at 300 hours skipping a service is risky unless your inspector is happy to allow the engine to be operated "on condition" after passing a TBO point.

Usually at this age piston rings will be found well gummed into their lands allowing blow by, little end bearings and gudgeon pins will be a bit slack and the outer main bearing seals worn enough allowing a bit of primary compression loss.

Add to that inevitable cracks in the carb rubbers and maybe the fuel pump pulse line.

All in all not a lot of cost for 300 hours of satisfactory operation.

Thanks for the information but this only confirms what happens now. My point is that other countries have determined that current practises are, although less risky, maybe "unnecessarily Robust" they have determined that service intervals can be extended with out increasing risk beyond an acceptable level.
The evidence that I have is limited but does confirm that our practises could be brought into line with the SA example without significantly increasing risk.
You could also argue that unnecessary stripping of engines actually increases the risk.
I raised the topic to find out if others in our group have similar findings.
When you say “Usually at this age piston rings will be found well gummed into their lands allowing blow by, little end bearings and gudgeon pins will be a bit slack and the outer main bearing seals worn enough allowing a bit of primary compression loss.” My experience is that this is not the case, if the engine is used with the fuels and lubricants as recommended it is far from usual to find those conditions.
With regards to Carb rubbers and fuel pump condition, not really and argument to strip out an engine crankshaft because of a problem with a carberretor?
Roger

I have a 582 silvertop. I did change the crank at 300 hours as I still had the old crank with the smaller big ends, so felt it best to upgrade.

From the strip report on the engine, the old crank actually was showing no wear at all with both cylinders measuring .042 using the Cyclone crank testing gadget. One piston ring was slightly stuck for about 10mm of circumference although no evidence of any blow by was present. It probably freed off when the engine warmed up.

Otherwise the motor was in excellent condition. The rotax enginer that did the work said it was the best condition engine he had seen for the usage. He also estimated that with the new crank the engine should be good for 500 hours before the next strip.

The motor has to date been totally reliable. I routinely cruise at 5800 to 6000 rpm and its turbine smooth and burns 15 litres per hour. I can stooge around at 80 knots and get 11 to 12 litres per hour.

I've never de coked it until the 300 hour overhaul as it burned very cleanly, just the usual gander in the exhaust ports at 50 hour intervals.

I am fastidious with fuel straining, only use top quality oils and I'm completely anal about thoroughly warming the engine and all the coolant before revving it up.
Rob Freestone

If your engine was the best he'd seen Rob, then perhaps others show a little more wear?

It's not as though the 582 is a particularly challenging or expensive engine to strip down and rebuild. If it were me I'd probably just do the overhaul .