First flight after overhaul - Issues.

[AmigOne]

The shop reported airplane ready for the first flight after o/h. Perfect day, CAVU and about 48F. Started up quickly, MP gauge showed about 1.5" higher than the ATIS barometric pressure (I knew that the gauge had this error). I do a quick mag check just before take off, no prop cycling. On the runway, full power, everything looks OK, rpm just below redline (tach was also o/h), gear up, flaps up and a shallow climb of about 400 fpm, a funny smell probably from paint somewhere (valve covers), nothing unbearable. At a 1000 AGL no alarms yet from the JPI (set at 450F), scrolling thru the cylinders all between 425-440F, fuel flow indicates 13.5 gph. Continue a shallow climb at full power, the idea is to circle for the next hour over the airport. At about 3000 ft one cylinder is at about 470F all others below, specially #3. I reached 5500 and settled down for the one hour flight, OAT is 32F, all cylinders now below 450F and quickly below 400F, #3 even below 300F. MP shows 32", RPM 2600, 13 gph, at this altitude the POH says it represents 72% of power. Oil temperature about 170F. After 15' I reduced to 60% power and flew for another 10', then I went back to 70+% power but I noticed that the MP gauge did not move. I moved the throttle back and forth but the needle was stuck at about 30.5".

Everything else is normal, the airplane smooth as silk, placed my hand over the glare shield and the engine could be stopped from the lack of the smallest vibration. Since I don't have MP information I decided to set power by fuel flow from the POH as I didn't want to land until I had the full hour. Then out of the blue the bars on the JPI cylinders 1#2 go out but the digital information continued. Interesting never happened before, anyways no big deal. When the time was up I started a shallow descent at 60% power, can't do more as the speed is already more than half way within the yellow arc. I noticed that the MP indication begins to climb from where it was stuck at 31.5" all the way to the top of the scale. The bars on the JPI are back for all cylinders and showed that the EGT is climbing, at about 2500' they are pegged to the top although I have began to reduce power to slow down.

I land normally and reported the happenings to the shop. Regarding the JPI they can't understand the high EGT, "impossible" they said and I would tend to agree, regarding the MP we all knew it was not working properly (1.5" too high), but now it has gone crazy. They looked over the engine but found nothing wrong. Keep flying they said and since I'll be at full power and can use the fuel flow as guide I guess it is OK.

What do you think, any ideas, is it just a bad MP gauge?, has this happened to anybody before? should I keep flying? Obviously I'll send the MP gauge for o/h but because it is a combination MP and fuel pressure gauge so I'm told is expensive, about $650+ !!!

[kmyfm20s]

The line for the MP guage most likley came loose or not tightened on install, on my plane it goes to #1 cylinder.  I would be concerned about the low fuel flow at 13.5 gph and the hot cylinders. Is that as rich as you can go?

[BigTex]

I actually had my MP connector come loose in flight.  The MP gauge became a barometer.  The engine would run fine until I pulled power.  If you backed off the power, the #1 cylinder would go cold and the engine would start running extremely rough.  It doesn't sound like his engine had any issues with roughness.

[orionflt]

Contact me about the manifold pressure gauge, I replaced mine with the MVP 50 so I have the one I removed sitting on a shelf. As for your cylinder temps, they are on the high side during the climb, especially for the fuel flow, but that is also the first flight after the overhaul so I wouldn't get too worked up over any of the numbers unless they continue. On my first flight my hottest cylinder hit 430, and I had Egt spreads of 100 degrees, and my cylinder temps are below 400 during the climb with flaps closed 46 deg Oat.

Brian

[N201MKTurbo]

The shop should be able to IRAN the MP gauge for less then that.

 

You can usually have it bench tested between free and $50.

 

For an overhaul they pretty much keep the case and replace everything else.

 

Be very careful removing that gauge. put a wrench on the AN fittings so they don't turn and carefully remove the B nut on the hoses. If you don't you will twist the fittings in the instrument and your repair bill will escalate significantly.

[AmigOne]

You are right, I checked my notes on take off fuel flow was about 14.6 gph. As to the hot cylinder it did not last long. I doubt that the MP connector came loose in flight and I want to think that this is the first thing that the shop checked after my report. Besides there was no roughness whatsoever, everything was silk smooth.

[AmigOne]

Thanks for the advice, I certainly don't plan to remove the gauge myself but I will make them aware of your comment. This shop is pretty good as they service high performance airplanes but I will tell them anyways.

[kmyfm20s]

You are right, I checked my notes on take off fuel flow was about 14.6 gph. As to the hot cylinder it did not last long. I doubt that the MP connector came loose in flight and I want to think that this is the first thing that the shop checked after my report. Besides there was no roughness whatsoever, everything was silk smooth.

 

I would just  have them double check. I can't tell from what you said above but if you are carburated and your #1 cylinder was 470 and the same EGT probe goes blank and your MP line connect to #1. You will have a induction leak causing a lean mixture and low FF.  I could be totally off and it's just your guage.

[John Pleisse]

Jose.... did they test fly it? Anybody who hangs a new engine should. The 13.5 FF concerns me. Mine are typically 18+gph too. In your entry, you keep mentioning "shallow climb", but you reference full power. A shallow, underpowered climb could generate the high CHT's, but those are summer time numbers, not winter time, Culpepper, VA numbers. As for the MP gauge, there is no excuse for this after a new engine installation and I'd reckon if that is wrong, there is likely error with your JPI and Shadin as well. Since I am in the same metro, may I ask which shop hung the engine for you?

[AmigOne]

Indeed in the IO-360 fuel flow with 200 hp will be higher but my C has a 180 hp. The engine was test run in a chamber at Triad NC, the overhauler, prior to installation and then briefly on the ground by the shop to check rpm since I have a new governor. Meridian Aviation installed the engine, in my opinion they are an excellent shop, they work on Pilatus and Columbia but also all kinds of nice airplanes. A pilot who flies aircrafts to Europe takes them there all the time prior to the ferry flight.

The climb was shallow but at full power, as I am fully aware of engine break-in procedures, in fact full power was kept almost throughout the flight, except for a couple of brief periods and for descent. As I indicated when leveled at 5500 all temps were below 400F and #3 even below 300F. There is apparently some issue with the engine monitor since the bars disappeared briefly for cylinders 1 & 2 so I don't know what to think of the high EGT. The JPI fuel flow indicator has operated flawlessly so far (about 2 years since installation) as confirmed every time by comparing fuel used per the gauge with fuel put in at the pump.

[jlunseth]

I don't have a C and have never flown one, so maybe take my comments with a grain of salt (I have a 231).  I would not ever accept CHT's of 425-450 during takeoff, climb or any other time.  My thought is that the engine is running too lean.  I would not want to see CHT's over 400 and would consider even that to be on the high side.  380 would be better.

[Hank]

My Owners Manual shows full-rich fuel flow of 18 gph at sea level; I would be shocked if your '68 C is significantly lower than my '70 C. Sure, some things changed, but not the engine. I don't have fuel flow, though. The lean mixture would account for the shallow climb and high temps, too.

[KSMooniac]

You have a major fuel flow issue IMO!  You should be 17+ GPH at full power/full rich.  

[garytex]

Hank & KS are right. Fix the fuel flow or it will bite.

[Parker_Woodruff]

Get that fuel flow up!

[scottfromiowa]

Get that fuel flow up!

+1

[carusoam]

MP gauge on the C probably has a small diameter (like 1/8”) aluminum line running to the closest back cylinder.

The line has a drilled hole in it. A calibrated leak.

The aluminum has a tendency to crack open and break where the hole is drilled. This really messes up the calibrated part of the leak.

So...

The engine has been pulled and replaced. All the instruments have also been disconnected and reconnected. Expect the shop to want to check their work, again. They will check for various leaks while they are in there.

CHTs, rpm, MP, oil P &T, fuel P at least.

As for the MP, if it is showing higher than expected, the hole is opening up or a leak is going on. Maybe tightening the fittings is all it takes. Get a visual on the hole.

There is a particular dimension to the leak hole. Finding the dimension relies on a drawing from the instrument panel. The C drawing I have didn't have it. I think maybe that I got it from an F....

Best regards,

-a-

[Cruiser]

470°F CHT is alarming even for a very, very short time. What is the redline for your engine? I thought Lycoming has a 450°F upper limit?

 

Get the engine properly instrumented. How do you know if there is a problem when you can't trust the gauges? If you have a 100°F spread on CHT (some 400 and one below 300) there is something wrong. 

 

Oh, and get the FF up, 13.5 gph is too low for full power takeoff.

[stevesm20b]

Sounds like the fuel flow is to lean. Did you notice what the fuel flow was before the engine overhaul?

[AmigOne]

Fuel flow before o/h was never 18 gph! and frankly I can't believe a 4 cyl 180 hp will draw that much but maybe I just gone dumb because I used to fly a Cessna 210 with a ff that high on t/o. Redline for this engine according to Lycoming is 500F, not that I would ever want to be anywhere near that temperature. I don't think that a 100F temperature spread between cylinders is alarming because this is a carburated engine with very uneven fuel distribution and cooling. Thanks for all the useful comments, please keep them coming. I may disagree with some but that does not mean that comments are not appreciated it. I will focus on the fuel flow and will not fly again until this matter is investigated and resolved. I'll drive to the airport and check the manual, Caruso, your comment is very interesting and I will mention it to the shop. Brian I will be in touch.

Happy New Year to everybody!

[jetdriven]

I think the carburetors run a little leaner than an IO engine with the Bendix RSA-5 injector but 13.5 GPH sounds alarmingly low. A quick check of VAF those guys are getting 15.5-17 GPH full rich on takeoff.

Check the throttle is opening fully. If it doesn't the economizer circuit won't open and you won't get that extra fuel flow provided by it. If that checks out then look at the carburetor. Another thing is the K-factor on the engine monitor. If the setting is wrong it may display a bogus FF number.

[AmigOne]

I corrected on a previous post the fuel burn at t/o to 14.6 gph which according to most comments would still be too low. However I'm beginning to think that even that figure could have been wrong, hopefully misreading on my part since I never expected it to be an issue. I was more concerned with the performance of the new scimitar propeller. I will download the JPI information on the first flight to be sure about temperature progression in every cylinder, unfortunately my model does not have the fuel flow integrated which is in a separate gauge (JPI 450).

[orionflt]

If your ff was 14.6 it is onthe lowsidefor takeoff, but as for. The other. Temps onthe first flight they were not far off for the initial breakin. My temps were all over the place for the first hour and 1/2, then it was like some one turned on a switch and everything settled into normal parameters. My next couple of flights I found minor tweaks that were needed, but all my temps looked good during climb and cruise. Fix the squawks that you positively identified and if your baseing your FF off of what you saw, not what was logged then tak it flying again. If you can take some one with you to monitor the engine or maybe set up a camera that you can review after the flight. I know I was too busy to note all the numbers on take off and climb but I could down load the flight data and review it when I landed, that was extremely helpful for me to determine that some of what I was seeing was just the engine getting everything seated properly.

Brian

[rbridges]

I corrected on a previous post the fuel burn at t/o to 14.6 gph which according to most comments would still be too low. However I'm beginning to think that even that figure could have been wrong, hopefully misreading on my part since I never expected it to be an issue. I was more concerned with the performance of the new scimitar propeller. I will download the JPI information on the first flight to be sure about temperature progression in every cylinder, unfortunately my model does not have the fuel flow integrated which is in a separate gauge (JPI 450).

 

I typically see 15-16 on take off at full rich/full manifold.  I do have a powerflow exhaust, but I don't think that would make too much difference.

[orionflt]

I just checked my numbers and I'm seeing between 16 & 17 on take off roll, and by the time I'm approximately 1000ft AGL I'm down to around 14 GPH. I think your FF is correct, you just didn't note the max numbers because they were during the critical portion of the flight where you were flying the aircraft (as you should have been) not looking at gauges.

Brian