Rotax 921ULS info from Phil Lockwood

[edwalker]

First of all, apologies about the long paragraph - the website is not responding to line feed requests. I spent some time yesterday at the NW EAA FlyIn at Arlington WA and attended an excellent forum on Rotax engine maintenance by Phil Lockwood of Lockwood Aviation in Sebring Florida. For someone who grew up with Lycomings and Continentals this was a major revelation to see how Rotax has raised the bar on efficiency and reliability. The main message was that these engines were remarkably well built, and that if one follows the recommended maintenance schedule, particularly oil changes, they should last forever. Even the 2000hr TBO engines he's seen rarely need replacement parts. I asked him some specific Phoenix-related questions that have not been entirely clear to me. The first was on engine burping and pulling through the prop prior to start. He said that normally he rarely does this, and it only really needs to be done if the oil is below the land (flat part) of the dipstick on inspection. The purpose of the burping is to pull all the oil back into the sump to get an accurate oil level for purposes of seeing if more needs to be added, and his experience is that it is rare to need do that between oil changes. Also, the prop does not have to be pulled through prior to start. In Lycoming and Continental engines that sometimes is recommended to coat the cylinder walls with a thin film of oil after an extended period of inactivity, but he said that the special coating on the 912 cylinder walls does not require any additional lubrication prior to start. So the rule is, basically, if you see enough oil on the land, go ahead and start without burping. The second issue comes up after soaring. I told him that the engine cools after extended soaring, and that, because I often land under power to be able to taxi, I have a long period of trying to get the oil back up to 120F, which is challenging if you are also descending under low power in cool air. He said that we don't need to worry about that. Unless you plan on doing touch and goes that require full power, he said it was fine to land and taxi with cooler oil temps. His cutoff point for needing 120F is 4000 RPM, so landing and taxi should be fine. He mentioned that he sometimes will take off at 4000 RPM even before the engine is fully warm. His only other major point was to be sure that the carbs are balanced since failure to do so puts asymmetric loads on the gear box and makes gear wear more likely. One other point got my attention. The Rotax water-cooled heads prevent shock cooling that is common on air-cooled engines, so the ultra-long, planned descents under significant power to gradually cool the engine aren't necessary with the 912ULS.

Edited July 14, 2013 by edwalker

[chasers03]

Ed this jives with how I have been treating my 912 UL in the Lambada. Seldom burp only when preparing to change oil. And I will taxi without engine warmed after a dead stick. I went to Dean's / Lockwood's 2 day school and it was well worth the time and minimal cost. I also learned the best way to change oil/filter which I can now do in less than 35 minutes. BTW I change (Aeroshell Sport) oil / filter every 20-35 hrs and ONLY burn 100 octane No Lead airport fuel. My engine is approaching 1500 hours and I plan to go for 2000 at the rate of 170 per year.