I got my plane in December, 2013 at just under 1,500 hours TTAF&E (wet head done at 1,000 hours). The only engine work I've done was replace the front crossover tube on my exhaust system. Prior work was Cyl 1 & 3 exhaust stack segment replaced. My Tach time is just under 1,800 hours and all compressions have consistently been in the mid to high 70's.
The only real engine-related work done on mine with 1200 hours is a rebuild of the exhaust collection tubing. Of course, Lycoming did an effective "overhaul" when I had the crank AD addressed...basically got a bunch of new discounted parts (new crank, rings, etc.) and some full price parts...new rockers, push rods, etc...
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Good Topic Dave because I have been studying these numbers for a while. I have been using the magic number of 58 (MP + MPH) for break in at 75% power for the past few weeks on my Factory Rebuilt engine and after 8 hours there is negligible oil burn (1/4 quart from "topping" the oil sump at the10 quart limit) and CHT's are now around 375 at the 58 setting. I did look at your post before I first flew the engine and I guess since Mike Elliott and the PPP both agreed on 58, I used it, taking nothing away from Don Kaye.
I bought the factory rebuild after putting 2100 TT on the Bravo even though the engine was strong, smooth, good compressions (except one cylinder), and very little oil burn, clean filter and oil analysis. I did it because I do fly my family and friends over mountainous terrain. I asked Don Maxwell at Oshkosh last year if Bravo owners ever go over TBO and he said yes, all the time. But only over it by a few hundred hours. So that sealed the deal and started talking to Lycoming at the booth there in Oshkosh.
10. Read your engine instruments very carefully during the entire flight. Pretend like their your attitude indicator during an IFR flight. Bring a co-pilot with you if necessary to help share in the work load
Normal SOP for me is TIT limit 1650 and CHT limit 400, but would take a higher CHT (say 420) if I had to climb for an ATC restriction or terrain cleananceas long it it was only a few minutes. I also try to manage cooling (myth or not, I'd rather not be cracking heads if it is avoidable).
TT 1900 hours, new turbos with previous owner, then I got 1000 hours out of the last one, two new cylinders, one early in its life and one from me at about 1700 hours, the other 4 are original with good compressions. Oil consumption is about 5.5hours per litre/quart. I bought the aircraft with about 1400 hours on it
Ron, as you may recall I am about to follow in your foot steps when my reman gets delivered and hung. I don't think I understand your power setting formula, i.e. What "mph" stands for. What mp and rpm setting are you using to yield 75% power? For me it has been around 29/24, (53) as described by Dave above.
When Ron called me, I did tell Rocketman I would run the first couple hours hard, like at 34/2400 then vary the rpm, but defer what I say to what the Lyc break in manual and Don Maxwell says to do. These engines are rated to be run at 100% power to TBO. Don M also said for Ron to run it at 34/2400 for the first few hours, if I am not mistaken.
Don - I am looking at the little red Lycoming book on page 3-48 which plots out percent rated horse power to fuel flow on the TIO-540 A series engines. This graph shows a 75% rated hp to a fuel flow of 105 pounds per hour or 17.5 gph. That fuel flow seems way to low for that power setting. Likewise the graph shows a 100% rated hp at a fuel flow of 175 lbs per hour or 29.1 gph. My 100% power on TO is higher than that setting. Something does not seem right about this graph. You know way more than I do Don so your expert opinion is again appreciated.
I'm not at home right now, but am out doing 2 initial Ovation 3 transition trainings right now. But one thing I can tell you until I get home on Friday and pull out the correct chart is that this is NOT the correct Chart for the TIO540AF1B engine. It was an insert into the book.
I am just trying to figure this out as I break in my new engine. If I go to low on power settings, oil burn will increase throughout the life of the engine and the rings will not properly seat against the cylinder wall. If I go too high while maintaining comfortable CHT below 375 with the cowl flaps open and a richer mixture, whats the problem? After all the engine is rated to 2000 TBO at full power. I wish Lycoming would have published real figures instead of leaving us to figure out the "politics" of HP settings and engine break in.
They gave some guidance that was pretty specific to the first two flights. The next flights were changing power settings every fifteen minutes varying RPM and MP. Using the MAPA guidance for 75% and 65% hp. Summing the Rpm/100 and mp numbers.
Filling the oil to the top level is good for keeping oil cool. Flying near to the ground is good for keeping cylinders cool and for NA engines high MP is best down low to help seat the rings properly...
I rented the skills of some MAPA CFIIs to specifically help with the break-in of my factory reman engine. Low flights over the ocean along the Jersey shore. I would have to look closely at the JPI data to even tell there was a break-in going on. The actual break-in was probably done on the Dyno at the Continental factory, or maybe the first few hours that the mechanic flew it...
I was thinking that together we can take a few steps to get to a sane usable set of limitations, flows and power with limits: I suggest we start with MP and RPM, then add fuel flows, and then from that we can overlay resultant power.
To this end, here is an alternative 'graph' of MP and RPM, which is so far solely my understanding and interpretation of Mooney PoH 3502 Rev H (28 Apr 2005) and Lycoming 60297-23P-2 4th Edition (Oct 2006). It's not overly pretty or neat (it can be tidied up when we have agreed the numbers/bands) but is hopefully a starting point. Parts I am particularly unhappy with are the areas for notes 4, 6 and 9, but I'm looking for constructive suggestions for the whole lot
Good chart.
You are the only Bravo driver I know of that can run LOP. I have tried but the engine just isn't happy doing it (and either am I!).
I stated my limitations and power setting in my original post but here they are again:
Cruise climb for me is from 29"-32" and 2400 RPM. If I lean in cruise I lean to keep CHT's under 400 dF with resultant FF from 20-24 gph.
I don't usually get close to 35" MP except when OAT is very low and have never seen over 35.5". On takeoff I typically get 34.5" and 2575 RPM. Once 1,000' AGL I reduce to cruise climb as stated above unless I need maximum climb rate.
I'm not sure either of the stated key numbers are valid and I think we should just state temperature limits and MP/RPM/FF settings with variations in FF to adjust temperatures.
I just got my latest oil analysis back from Blackstone and they think my engine is in great shape (see attached). So I think my power settings work well for this engine.
It's probably marginally smoother at 2400 than 2200, but not significantly. I think I need to have a prop balance, as the vibration is a bit high for my liking, but I need a prop reseal anyway as one of the de-ice boots is starting to perish, and I'll get that all done together when I go over to Straubing for the avionics work later in the year (MT prop HQ is at the same field, and they service the standard McCauleys)
I discussed performance figures with Mooney at Sun-n-Fun recently and they reminded me that the engine is actually rated much higher than 270 hp so the actual performance figures should be adjusted accordingly. Just because it was derated to 270 does not mean that the 270 is 100% hp, especially during break-in procedures. Interesting thought. The truth of the matter is that there is no absolute truth to this matter! 152ee80cbc
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