JohnL Posted July 31, 2013 Report Posted July 31, 2013 Anybody know why cylinder #2 seems to be the most problematic on the Rockets? I've just test flown a Rocket where cylinder #2 overheated (above 460) on a climb to 14k. Looking at logs from others, it seems cylinder work always includes #2. According to a mechanic working on the test flown plane, the cylinder is located on the pilots side closest to the firewall, but in front of the oil cooler. It does look like it would be the most challenging to cool. Baffling looked OK and sealing looked OK to the cowling. According to the logs, the owner had pulled and honed the #2 cylinder about 25 hrs earlier, and owner was saying it may just need more break in. I'm not sure that really sounds right. Shouldn't it have settled down in 25 hours? Now, looking at another plane, cylinder #2 has been replaced due to low compression while all the others have passable compressions (66, 68 and in the 70's). Will this engine (800 hrs TSREMAN) be OK if treated well (CHT below 380)?.
bd32322 Posted July 31, 2013 Report Posted July 31, 2013 Cylinders take a variable amount of time to break in. On this forum, there are reports of a few hours (2 or 3) to 100 hours. Dont know specifically about rocket's cylinder #2 though. 460 seems very high though .. altho depends on how it was being flown then ofcourse.
aviatoreb Posted July 31, 2013 Report Posted July 31, 2013 Anybody know why cylinder #2 seems to be the most problematic on the Rockets? I've just test flown a Rocket where cylinder #2 overheated (above 460) on a climb to 14k. Looking at logs from others, it seems cylinder work always includes #2. According to a mechanic working on the test flown plane, the cylinder is located on the pilots side closest to the firewall, but in front of the oil cooler. It does look like it would be the most challenging to cool. Baffling looked OK and sealing looked OK to the cowling. According to the logs, the owner had pulled and honed the #2 cylinder about 25 hrs earlier, and owner was saying it may just need more break in. I'm not sure that really sounds right. Shouldn't it have settled down in 25 hours? Now, looking at another plane, cylinder #2 has been replaced due to low compression while all the others have passable compressions (66, 68 and in the 70's). Will this engine (800 hrs TSREMAN) be OK if treated well (CHT below 380)?. 460 is a major major problem. Even if you keep the climb relatively shallow and the climb IAS high?! What kind of temps does that cylinder show during cruise? Could there be a problem with your baffling? My rocket is fabulously cool. It is easy to keep the hottest cylinders in the 350ish range during cruise, and even in the summer I can keep the hottest in the low 380 range even in a sustained climb. If it is a short climb say to 5 or 6k then they never touch 380 if I keep cowl flaps open and speed up - but still easy to make 1000-1400fpm depending on temps. If it a long climb say to the mid teens then by 11 or 12k I do sometimes need to start tipping the nose down a bit to keep temps nice and cool so with the nose down a bit in the mid teens the fpm falls to just below 1000fpm, but the IAS goes way up over 140 and temps stay nice and low still. In the winter sometimes I climb with cowl flaps closed and this gives me roughly 10 more kts IAS and I can still control temps with airspeed/pitch as my tool, to always be no more than ~380 in climb. I did do a complete top at 985 hrs - about 75 hrs ago - I had 1 very bad cylinder and 2 mediocre cylinders so I did all 6 while I was at it since in the rocket it is quite a bit of work to pull off the exhaust and get in there. What we noticed is the reputation seems correct - the continental cylinders from about a dozen years ago are not so well manufactured - even the still healthy cylinders. The valve seatings are not particularly well machined or well seating. I replaced them with a complete set of ECI Titans that I had further reworked (despite that they were new) by Victor Aviation. It was then night and day the difference in the quality of workmanship of the valve seatings in my new cylinders than the factory cylinders. I am convinced this is a major factor of why Continentals often need cylinder work at 1000hrs or so no matter who the pilot is handling the red knob.
thinwing Posted July 31, 2013 Report Posted July 31, 2013 Thats been my experiece with 540 continental jugs...they just dont seem to go to TBO without valve work about 1000 hrs...Usually do to low compressions...this was also true of earlier 1970 s jugs and the agpilots /mechanic were saying they need to be run hard at 25 squared all the time to make tbo.Didnt understand why but got much better service life doing just that
JohnL Posted August 1, 2013 Author Report Posted August 1, 2013 Thanks for the information guys. We were climbing at about 120 or so and at first temps looked fine. I wasn't flying, just observing. At the top of the climb I noticed the engine monitor alarm had gone off on cylinder #2 (flashing 460). The pilot slowed the climb but we were leveling off at 14k at that point anyway. I really didn't have much ability to monitor temps after that. BTW, the full power fuel flow was 29.1gph according to the fuel flow readout. I noticed Rocket calls out 31.5 gph for full power. Is that a material difference? Perhaps bowing to the inevitable... how much should I budget for a top on the TSIO-520NB?
RJBrown Posted August 1, 2013 Report Posted August 1, 2013 Thats been my experiece with 540 continental jugs...they just dont seem to go to TBO without valve work about 1000 hrs...Usually do to low compressions...this was also true of earlier 1970 s jugs and the agpilots /mechanic were saying they need to be run hard at 25 squared all the time to make tbo.Didnt understand why but got much better service life doing just that 540? thats Lycoming, Continental is 520 or 550. Eric repeats my Rocket experiance. Never did run hot. Used to piss me off when the cowl flaps stuck open. Ran too cold and slowed me down.
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