Savy Analysis and LOP Test

[Txbyker]

I wish to share my experience in finding an issue with my ignition system.  I really like the Savy Analysis tools.  I can sit on the PC for hours and view the data from my flight logs.  

For the past several months I noticed a stumble while flying LOP.  I call it a stumble but once at LOP I feel a very quick shudder almost like turbulence for a nanosecond.  All engine indicators are in the green.  After researching this a bit more I decided to test the ignition to see if something can be revealed as a weak link.  I have a new ignition harness, recently overhauled mags, and Tempest fine wire plugs with 300 hours on them.

I flew at 8500 and ran an LOP mag check per Savy instructions.  Their detailed flight analysis  showed the following.  The L, B, and R stand for "left mag", "both mags", and "right mag".  Note the EGT1 going cold during the right mag test.

 While on the right mag, sparkplug on cylinder 1 was cold.  It was not even firing I do not believe.  The engine was rough on the right mag.  I replaced the plugs on cylinder #1 and ran another test.  Indeed the bottom plug was bad with a cracked insulator.  My A&P said it looked like it had been dropped.  See the new data with new plugs in #1.

Now temps are normal and the engine was very smooth at 50 LOP.  

Savy has some very nice analysis tools and I appreciate the help in determining the source of the issue.    Just sharing this information in hopes it helps someone.

Russ

 

 

[Cruiser]

nice find. Thanks for sharing.

[Jeff_S]

Good stuff Russ.  Always good to get experiences for how to diagnose actual in-flight experience with the Savvy data.

[carusoam]

Nice work, Russ!

Thanks for sharing the graphs.

Is the TIT1 a TC in the actual ship's EGT hole? (After the 3 into 1 exhaust pipe)

That is the first time I have seen digital data from that spot in a NA plane. Showing how the 3:1 data reads higher than the individual EGTs... a function of getting an average number...

There is often hokey explanations for this effect in the turbo world...

Best regards,

-a-

[MIm20c]

19 minutes ago, carusoam said:

Nice work, Russ!

Thanks for sharing the graphs.

Is the TIT1 a TC in the actual ship's EGT hole? (After the 3 into 1 exhaust pipe)

That is the first time I have seen digital data from that spot in a NA plane. Showing how the 3:1 data reads higher than the individual EGTs... a function of getting an average number...

There is often hokey explanations for this effect in the turbo world...

Best regards,

-a-

Makes sense, use the probe and previous hole from the factory egt location and put it to good use. 

[Raptor05121]

8 minutes ago, MIm20c said:

Makes sense, use the probe and previous hole from the factory egt location and put it to good use. 

Are we doing phrasing anymore?

[ArtVandelay]

44 minutes ago, Raptor05121 said:

Are we doing phrasing anymore?

Nice Archer reference 

[Raptor05121]

[Txbyker]

8 hours ago, carusoam said:

Nice work, Russ!

Thanks for sharing the graphs.

Is the TIT1 a TC in the actual ship's EGT hole? (After the 3 into 1 exhaust pipe)

That is the first time I have seen digital data from that spot in a NA plane. Showing how the 3:1 data reads higher than the individual EGTs... a function of getting an average number...

There is often hokey explanations for this effect in the turbo world...

Best regards,

-a-

Yes Anthony, the 3 into 1 probe shows up on Savy as TIT.

Russ

[carusoam]

8 hours ago, MIm20c said:

Makes sense, use the probe and previous hole from the factory egt location and put it to good use. 

The goofy part of my question is probably more of a labeling issue....

1) the Ovations and Eagles properly use a Ship's EGT gauge for leaning during the climb and cruise. Blue box for the analog gauges... white box for the digital G1000 display....

2) The ship's EGT gauge is after the three-into-one exhaust pipe. A lot hotter location,  on average, than the single EGTs upstream.

3) Turbine Inlet Tempurature (TIT) is usually an operational temperature for turbocharged or turbo normalized engines.

4) This is a mis labeled device, since the Ovation doesn't have a turbo.

5) Savvy probably got the label from the G1000 system that is doing the same mislabeling confusion.

6) Some value to this conversation is found in why the ship's EGT gauge and TITs are found to be increasing, after the fuel is known to stop burning...and exhaust gasses are continuously expanding...

It is great to have the seventh EGT sensor, or ship's EGT gauge.  It would benefit from having a name that describes what and where it is...

Kind of a thermodynamics aha moment... 

Best regards,

-a-

[Txbyker]

19 hours ago, Jeff_S said:

Good stuff Russ.  Always good to get experiences for how to diagnose actual in-flight experience with the Savvy data.

Thanks to you for getting the M20R’s profiled in Savy!

 

[Jeff_S]

For the G1000, the "TIT" is indeed the 3-into-1 temperature reading that gets displayed on the summary engine readouts when the MFD is in non-Engine mode.  It's always about 100° hotter than the actual EGTs on that side.  I am guessing that in an Acclaim or Bravo this would indeed be the probe used for TIT.

[carusoam]

Good statement, Jeff...

1) The G1000 doesn't need to differentiate where the extra probe is exactly mounted to work properly.

2) The turbos usually want the TIT gauge integral with where the blades are going to be running. The exhaust tubing is specific to the turbo installation, so the 7^th TC hole the NA engines have isn't going to be there anyways...

3) The Acclaim has two TNs. I would Expect that the G1000 must be able to have a TIT2 to go with that TIT1...?

4) in an ideal world one TIT would be indicative of the other. However, A single bad plug would send TITs to a high level on one side, but not indicate the same on the other...

PP thoughts only, if there was an STC to put a pair of snails on the O, I would have gone TN... during the OH....

Best regards,

-a-

[Bob_Belville]

I spoke to Mike Busch who made a presentation to a full tent at AOPA Fly-In Saturday. I mentioned "our own" @kortopates and how helpful Paul is... he reacted to the effect that Paul loves Mooneys and probably grabs all the Savvy subscribers who have straight tails.