Continental TSIO-520 on C207 - one cylinder "different"

[Ericson]

Hello !

I'm the pilot that just got a chance to fly on Cessna T207A with Conti TSIO-520. The aircraft has EDM-700 engine monitor. I downloaded data and I'm little bit worried about cylinder nr 1 - as it shows signs of low compression or burned exhaust valve ( according to EDM manual - low CHT and high EGT ). During the flight engine runs quite smooth but I only logged about 2 hrs on it.

What is your opinion about engine condition ? ( engine graph is attached ). I've graphs for last ~15 hr and I can upload them if it helps.

thanks

[NzCaptainAndrew]

I'm guessing higher temps all round are due to the turbo.... looks within limits to me.. your better off checking in with a LAME they are always keen to helpout with any questions I suggest ringing your nearest?

Capt.A

[good spark]

sounds like time to do some good old fashioned compression testing and cylinder leakage testing!


gs

[ccgypsyblood]

This looks fine to me, here's the reason I'm saying that:

When you install a EDM 7xx you install six new EGT and CHT probes in the exhaust pipes and cylinder heads respectively. The CHT probes are installed in a pre-drilled hole located on the bottom of the cylinder head aprox. three inches inboard from the spark plug hole. The #1 mounting location however is already taken up by Cessna's OEM CHT probe, so a different type of probe called a "Ring Probe" is supplied with the installation kit to be installed underneath one of the spark plugs in that cylinder. This produces a "different" heat value for that cylinder due to the heat dissipation pattern of the cylinder head. (note that JPI states that "the gasket probe may read 25 degrees F. higher or lower than the factory probe", although I have seen bigger differences)
The OEM probe is installed in the #1 cylinder to begin with because it is usually the hottest running cylinder due to being in the aft r/h location, lots of heat can build up back there, as noted by the EGT reading. The recorded temps for #1 CHT & EGT are also corresponding at the same rate of change as the rest of the cylinders, no extra jumps of jitters, sure signs of sticking/bent valves.
Also, as a last opinion, a decrease of a full 1/3 of your CHT temp, if indication of a lack of compression and combustion would surely translate to a abnormal difference in EGT, which is not present.

All that being said, look at your EDM historical downloads if you have access, is this a normal reading for this engine? Is the aircraft fresh from a 100hr or annual where the CHT probe may have been damaged or installed incorrectly? And really, it's never a bad idea to crack the cowling and take a look at it, a quick compression check would put any doubts to rest.

Definitely discuss this with your local mx guy though, better safe than missing a cylinder at 10k feet

CC

[Big Pistons Forever]

The Number 1 CHT (C1 redline on bottom). Can't be correct as it is 75 deg cooler than the average of the other cylinders. Since the No 1 EGT (red line on top) is pretty close to the other cylinders I would say that the CHT probe on No1 has failed. As was pointed out the factory CHT ( ie the one in the panel engine gauge cluster) comes off No 1 so the first thing I would do is see what it shows on the next flight.

I am also curious that the EDM 700 does not have a TIT indication. That is how I lean these engines. That is just lean to a TIT value (1425 deg F for short trips 1500 for longer cruising at altitude) which is a quick and easy way, although individual cylinder EGT/CHT must obviously be monitored.

The big issue for engine life is keeping the CHT's down. From your graph the spread on the CHT's (No 1 excepted) looks good.