jetdriven

Joined: Jun 15, 2011 Posts: 14 Location: New York NY Re: What CHT requires cowl flaps in cruise? Posted Jun 19, 2011 11:15 PM I'd like to thank everyone for their advice. I flew again today and tried some more LOP stuff (right now just playing with things and getting a feel for leaning and the plane since I just got it recently). I'll read the articles again cause after the tests I've done recently, they may apply to me afterall. When I read them, I didn't take them too seriously because I didn't think I could fly her Lean of Peak. Here's what I got today: 3000ft, 26", 2600RPM, 150ktas, 45LOP, 367CHT (hottest cylinder, others were near 340), 9.7GPH. What my %HP was I have no idea, but I'm guessing 75% based on what you guys tell me with FF. Let me add that density altitude was more like 4500ft. FF (GPH) X 14.9= crankshaft horsepower. 9.7 GPH is 144 HP or 72%. 72% to the airframe is 72%. Here's the procedure I used to lean. Leveled off, left throttle full but pulled prop back to 2400RPM. I leaned mixture a reasonable ballpark toward peak. I set EDM700 for LOP and continued leaning through peak and until richest cylinder peaked. Then I continued leaning to 50LOP. I went past to test for roughness which occured by around 60LOP so I went back in to about 45-50LOP on richest cylinder. Fuel flow was reading about 8.5gph so I added RPM until I was close to 10GPH in hopes of achieving 75%. Then I closed the cowl flaps and was pretty happy the hot cylinder stayed below 380F. Here's a glimpse at the EGTs for all cyldiners at one moment after leaning: 1390, 1328, 1395, 1377. Peak was 1440. Should I be concerned about #2 running a lot leaner if engine isn't running rough? Am I doing things right? What am I at risk of screwing up if this is done incorrectly? Can I get any more speed out of her? Your procedure is basically corrrect. Richest cylinder is the last one to peak. Lean to LOP from this cylinder. Changine RPM changes fuel flow, and your degrees from peak probably will change. Re-lean. As I have learned, leaning past 50 LOP is less efficient and much slower. Most benefit is from peak to 40 LOP. EGT numbers mean nothing. The value they are in relation to peak is all that matters. If #2 is leaner than the otehrs whle LOP is no problem. Above 6000-8000' you rapidly paint yourself into a corner while LOP, meaning you end up only being able to produce 55-65% power. Speed suffers and peak or ROP might be more beneficial. A rough rule of thumb is LOP, you can add 2" of manifold pressure to the book charts for the same percentage of power. IE 23" and 2500 RPM ROP is 65% power, it takes 25" to make that 65% power if LOP. Your goal is peak to 40 LOP on your richest cylinder, 75% power or below, smooth engine, and no CHT over 380. 360 is preferrable. Do NOT exceed 400 degrees CHT on any cylinder. I am in the camp that you are not harming anything in that regime. That is peak BSFC and near the best efficiency and cost per mile. Our plane this weekend ran 380 CHT (#4), 40 LOP, 6500' altitude, 65 degrees temp, 2500 RPM, full throttle, and 141 MIAS. ff was 8.4 GPH, so ~62% power. New baffle seals go in this week. I'd like to run a little richer, with cooler CHT and a little more speed. If you cannot satisfy all these parameters, go to 75-100 ROP, richen to cool and later investigate why not. UPDATE: 40-50 LOP is the lean end of the range. Best BSFC is arund 15-40 LOP. Our newest procedure is 15-20 LOP.

My wife have done 187 MPH calculated on an air race course at 1000' and a 75 degree day. IAS was 185 MPH, and I would guess TAS around 190. This a a 5000 hour airframe, 1300 hour engine, not rigged perfect, droopy nose gear doors, and a couple extra antennas. We generally get 155 KTAS at 75% power, around 140-145 at 65% power.

The cowl flap linkage closes over center. Here are the rigging instructions from the SMM.

Mooney S.I. M-20-114 says to only lift any Mooney prior to the M20L by the engine lift point. They say to "do not" lift the nose by a propeller jack, and they do not recommend using the tail tie down point to raise the nose. here it is: http://www.mooney.com/images/pdfs/si-pdf/m20-114.pdf

Agree with KSMooniac. 25 ROP is right square in the middle of the "red box" taught by Deakin and the folks at APS. Thats the last place you want to be. Its just about at hot from 50 ROP to 10 LOP the curve is pretty flat there. Figure out why you can't run LOP and fix it. Its costing you 1-2 GPH. Either run 10-50 LOP, or 75 ROP at 75% power. At 65% power you can run at peak. If you can't, check bafflling and injectors. CHT at 65% power will be lower that at 75% power. The airspeed isnt all that much less, maybe 10 knots. but heat is less. Ours at 50% power are in the high 200s to 320. 65%, 350. 75% is 360-370. We can gain 20 degrees from new baffle seals, they go in this weekend.

Do not lift it by the prop. Lift the nose with a short length of chain attached to the lifting eye on the crankcase with a cherry picker. RSC rental places and the like rent them to pull car engines with. Truly, it is easier to anchor the tail tie down with a bucket ful of 300 lbs of cement that has a chain or pipe and linch pin attached to it. Mooney doesnt prohibit that they, just discourage that. As long as you are careful its fine. But lifting the prop with a saddle and a jack is bad.

if your injectors are dirty the mixture distribution wont be even. Run a GAMI test, and clean them if necesary. Perhaps your #3 and #4 are at peak when you are trying to run ROP.

The only airplanes I have seen them factory installed in were Lears. Turboprops, commuter jets and even the 747 all have the proper approach speed (vREF) based on weight, and the AOA takes care of itself.

Is she about to take to the air yet?

Left main wasnt downlocked (overcentered?) properly and the pushrod failed causing left gear collapse and ran off the runway. See the thread "insurance company question"

Our KLN-89B (And the KLN-94) doesn't output ARINC or RS232 outputs to drive a GPSS. The aera will, but thats not a certified GPS.

I have the factory well probe on #3 and this replaced my crappy spark plug washer CHT thermocouple with this http://www.overnitesupply.com/wtk38-2424typekwasherstylethermocouplegrounded38studsize24stainlesssteelbraidedleadssplitwithspadelugs.aspx I simply installed it under the factory CHT well probe. It now reads within 5-10 degrees of all the bayonet probes. It is just a standard "Type K" thermocouple. a 10$ solution.

our plan will hold altitude and heading. To get the glideslope or GPSS to fly in circles will cost us too much.

I'm in the same camp., you should never have to open your cowl flaps in cruise. The problem is either improper leaning (too rich, or too near peak at to high of a power setting) or your baffling is leaking. We are starting with baffling this weekend.

1800$ is a good price?

OK I just read it. They will upgrade your 20 or 30 system to a 55X for 9500$ plus installation. We have the S-TEC 30ALT unit. My guess is the 55X uses the same pitch and roll servos, so its basically a 12K upgrade cost to swap out the control head. For now, I will pass.

What is the cost to upgrade a 30ALT to a full 55X etc?

use a cherry picker like for removing a car engine.

you have to be ready to move quickly and make a contingent offer on the spot with a deposit.

My 1977 201 electric trim has stopped working. When we first bought it all was well. Lately the electric trim has gotten intermittent and the wheel is getting harder to turn. Now it does not work at all. We cleaned the switch with contact cleaner to no avail. Does anyone have any experience with these units, and does anone have any service info on them, or the manufacturer and model number?

I had a guy hand prop me in an IO-520 in a Bonanza I was flying once. You should have seen that, and no, I wouldn't attempt it ever.

since edit is broken, I'd like to update my post. From HERE: http://www.gca.aero/list.asp?search_type=7&search_text=27&search_text2=S-TEC it looks like the 30ALT is "from 8k installed" 60PSS is "from 10K installed" being able to have a glideslope capability is nice. I agree, the 15K for a simple two axis autopilot is ridiculous. Plenty of people would upgrade their airplanes if prices weren't so incredibly high. Cobham owns S-TEC and the legacy to Century, so you can call it "cornering the market". Killed it is more like it.

me too

We have the C-IIB and the STEC-30ALT combo installed in our plane. It was a nice thing to get with the plane. I like it. You turn on the Century, stick it in heading mode, then turn on the S-TEC and monitor it until you land. It does a pretty good job holding altitude. Usually within 20-40 feet. I have tried it in moderate turbulence. Ours has a button on the right side of the pilot's yoke which diesngages the altitude and re-engages, to change altitudes. It does NOT trim, so it beeps at you to trim. Personally I think its great in cruise and to get your charts together. I wouldnt use it on a non-precision approach. It has no glodeslope capability. For the 12K they want these days to install one? Thats a shocker. Ours was installed for 4K in 1999.

Either way I bet it would have ran for 2300 hours or till 74657 got tired of it, and when it came apart for overhaul, the crank would be tagged as bad then. It was working fine until discovered, it just can't go back inside an overhauled engine. Still, an unexpected 10-12 grand hurts.