Extreme CHT temps immediately after takeoff - 2nd post-maint flight that day - Mayday.

[TheMooneyAnomaly]

4 minutes ago, jaylw314 said:

I wish I could think of something useful to say that hasn't been said already.  I just went "urk" reading your account and am glad you're back on the ground safe, but horrified at your plight  

Thanks.

 

I think this is the most ungrateful I've ever been after surviving a potentially fatal event. Ha!!

[PT20J]

If fuel was removed for calibration and temporarily stored at the shop I wonder if it is possible that it was contaminated there? Maybe solvent unnoticed in the storage container? 

Preignition can be stopped by reducing the power. But if your event was a case of detonation caused by fuel contamination, I don’t think it likely that you could have saved the engine from damage given the low altitude when it occurred.

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[EricJ]

The fact that fuel may have been handled for weight as well as calibration suggests that there may have been multiple opportunities for contamination.    I'm glad that fuel samples were sent off for analysis.

 

[M20F]

What’s the deal with MP/RPM settings?  Those don’t make much sense to me for a IO360 unless I am really reading the graph and the screenshots wrong. 

[carusoam]

Full respect for the pirep….

quickly looking to get to the next steps…

The data is nice…. Kind of like a picture of your favorite child…. 

 

To get the most out of the community… share the data, not just a picture of the data.

 

To do this…

Go to savvy, click the share button… then post the link here…

There are a few engineers and mechanics and people that like this stuff around here… that can sweep through the data…

 

The one thing that stands out to me so far… is the saw tooth pattern in the MP line…  since mixture causes problems with detonation… there is definitely something odd with the MP (I think)

 

I love to click on savvy graphs, and alter the variables being shown…

See if you can share the link so we can click on the data…

 

Mis fueling with Jet A will definitely cause detonation with piston failure within minutes… typically resulting in gliding to a landing a few miles away…

Small amounts of Jet A may be able to hide… a tank full has a strong aroma that even a really old nose can’t ignore…

 

PP thoughts only, glad you are on the ground safely… please share the data… there is a ton to learn here…

Best regards,

-a-

[flyboy0681]

Cool heads prevailed, so to speak.

[TheMooneyAnomaly]

Mooney Family!

I have some good news!

The primary mystery is solved - the likely cause!

 

When the engine was overhauled last year, the prior owner declined servicing the fuel system.  That is one of the dominos in this chain.

My mechanic, after a number of inspections at the engine area, began training from the fuel & fuel tanks-forward.

Approximately in order:

Fuel - out to the lab, awaiting word.

Airframe fine mesh screen - no debris.

Fuel selector/gascolator - No debris, clean screen, nothing out of the ordinary.

Elbow before electric fuel pump - INTERIOR RUSTING

Electric fuel pump - INTERIOR RUSTING

Elbow after electric fuel pump - INTERIOR RUSTING

Coarse screen filter after fuel pump - no debris

Fine mesh screen inside fuel servo - BINGO.  Significant amounts of fine rust particles, sufficient enough to significantly and variably reduce fuel flow.

Combine this with the fact that we went to higher-flow air filter (PowerFlow Challenger K&N style) and higher-flow exhaust (PowerFlow) - increased air flow.

 

Secondary mysteries are:

  Why was the prior flight ok?

  Total extent of damage.  

So it seems that this aircraft had sat with water at times and may not have been regularly sumped by the prior owner... who also saved several hundred dollars, leading to a situation that caused loss of effective engine function, potential loss of life, and significant costs.

As my mechanic feels that he should have spotted this, he is covering all labor, cylinders, pistons, rods, bearings, bolts.  I am voluntarily covering a couple overhaul items, noted below.

Plan:

    Oil has been sent to the lab

    Oil filter paper portion sent to the lab

    Fuel from each tank separately sent to the lab

    Cyls 1 & 2 turning into trophies for the fireplace

    Cyls 3 & 4 going out for inspection

    Bearings being inspected right now. May be some marks in the babbit material.

    Replace mechanical fuel pump (precautionary) 

    Overhaul electric fuel pump

    Inspect and replace all connectors and elbows that may contain rust

    Overhaul fuel servo (precautionary) 

[EricJ]

Definitely have the servo overhauled, and check the flow divider as well for junk/trash.    I had similar issues and an engine failure (total power loss, though, not just lean) due to junk in the servo, evidenced by a finger filter full of rusty crap.    It actually had failed three times, intermittently where we thought we'd fixed it until it failed completely.   The overhauler said it was "full of grit".   I think if crap gets inside it and the diaphragms get sticky it can misbehave without warning, sometimes fix itself, etc.

Glad you found a culprit, and very glad to hear your mechanic is stepping up, which sounds like an incredibly solid move on his part.

 

[Ragsf15e]

4 hours ago, StPeteM20F said:

Mooney Family!

I have some good news!

The primary mystery is solved - the likely cause!

 

When the engine was overhauled last year, the prior owner declined servicing the fuel system.  That is one of the dominos in this chain.

My mechanic, after a number of inspections at the engine area, began training from the fuel & fuel tanks-forward.

Approximately in order:

Fuel - out to the lab, awaiting word.

Airframe fine mesh screen - no debris.

Fuel selector/gascolator - No debris, clean screen, nothing out of the ordinary.

Elbow before electric fuel pump - INTERIOR RUSTING

Electric fuel pump - INTERIOR RUSTING

Elbow after electric fuel pump - INTERIOR RUSTING

Coarse screen filter after fuel pump - no debris

Fine mesh screen inside fuel servo - BINGO.  Significant amounts of fine rust particles, sufficient enough to significantly and variably reduce fuel flow.

Combine this with the fact that we went to higher-flow air filter (PowerFlow Challenger K&N style) and higher-flow exhaust (PowerFlow) - increased air flow.

 

Secondary mysteries are:

  Why was the prior flight ok?

  Total extent of damage.  

So it seems that this aircraft had sat with water at times and may not have been regularly sumped by the prior owner... who also saved several hundred dollars, leading to a situation that caused loss of effective engine function, potential loss of life, and significant costs.

As my mechanic feels that he should have spotted this, he is covering all labor, cylinders, pistons, rods, bearings, bolts.  I am voluntarily covering a couple overhaul items, noted below.

Plan:

    Oil has been sent to the lab

    Oil filter paper portion sent to the lab

    Fuel from each tank separately sent to the lab

    Cyls 1 & 2 turning into trophies for the fireplace

    Cyls 3 & 4 going out for inspection

    Bearings being inspected right now. May be some marks in the babbit material.

    Replace mechanical fuel pump (precautionary) 

    Overhaul electric fuel pump

    Inspect and replace all connectors and elbows that may contain rust

    Overhaul fuel servo (precautionary) 

Oh man.  Great find.  Can you please share your mechanics name because I’d fly just about anywhere for that kind of individual.  Also, he needs a bottle of scotch when she flys again. 

[TheMooneyAnomaly]

Oh man.  Great find.  Can you please share your mechanics name because I’d fly just about anywhere for that kind of individual.  Also, he needs a bottle of scotch when she flys again. 

Agreed! I’ll DM you.


Sent from my iPhone using Tapatalk

[flyboy0681]

18 minutes ago, Ragsf15e said:

Oh man.  Great find.  Can you please share your mechanics name because I’d fly just about anywhere for that kind of individual.  Also, he needs a bottle of scotch when she flys again. 

Of course the A&P could have been watching this thread and decided to get ahead of the situation in order to avoid some really bad feedback from MSers. But he did do the honorable thing.

Just my 2₵

 

 

[Shadrach]

5 hours ago, StPeteM20F said:

Mooney Family!

I have some good news!

The primary mystery is solved - the likely cause!

 

When the engine was overhauled last year, the prior owner declined servicing the fuel system.  That is one of the dominos in this chain.

My mechanic, after a number of inspections at the engine area, began training from the fuel & fuel tanks-forward.

Approximately in order:

Fuel - out to the lab, awaiting word.

Airframe fine mesh screen - no debris.

Fuel selector/gascolator - No debris, clean screen, nothing out of the ordinary.

Elbow before electric fuel pump - INTERIOR RUSTING

Electric fuel pump - INTERIOR RUSTING

Elbow after electric fuel pump - INTERIOR RUSTING

Coarse screen filter after fuel pump - no debris

Fine mesh screen inside fuel servo - BINGO.  Significant amounts of fine rust particles, sufficient enough to significantly and variably reduce fuel flow.

Combine this with the fact that we went to higher-flow air filter (PowerFlow Challenger K&N style) and higher-flow exhaust (PowerFlow) - increased air flow.

 

Secondary mysteries are:

  Why was the prior flight ok?

  Total extent of damage.  

So it seems that this aircraft had sat with water at times and may not have been regularly sumped by the prior owner... who also saved several hundred dollars, leading to a situation that caused loss of effective engine function, potential loss of life, and significant costs.

As my mechanic feels that he should have spotted this, he is covering all labor, cylinders, pistons, rods, bearings, bolts.  I am voluntarily covering a couple overhaul items, noted below.

Plan:

    Oil has been sent to the lab

    Oil filter paper portion sent to the lab

    Fuel from each tank separately sent to the lab

    Cyls 1 & 2 turning into trophies for the fireplace

    Cyls 3 & 4 going out for inspection

    Bearings being inspected right now. May be some marks in the babbit material.

    Replace mechanical fuel pump (precautionary) 

    Overhaul electric fuel pump

    Inspect and replace all connectors and elbows that may contain rust

    Overhaul fuel servo (precautionary) 

I’m skeptical of the servo explanation. Temps on the previous flight were ideal. Not saying that servo does not look like shite, but it seems odd that it manifested all at once. Bendix RSA does not have a fuel return. So if the transducer was seeing that flow rate, it was going through the engine.

[TheMooneyAnomaly]

18 minutes ago, flyboy0681 said:

Of course the A&P could have been watching this thread and decided to get ahead of the situation in order to avoid some really bad feedback from MSers. But he did do the honorable thing.

Just my 2₵

 

 

Quite possibly, but I suspect he was not watching.

Unrelated note - He only took over servicing of this aircraft 2 weeks before the incident flight.

His checklist now include inspecting for rust in steel components and inspection of every...single...screen.

He is a very smart dude with an excellent memory... and clearly an honest person and person of integrity.  He has my trust.

[TheMooneyAnomaly]

14 minutes ago, Shadrach said:

I’m skeptical of the servo explanation. Temps on the previous flight were ideal. Not saying that servo does not look like shite, but it seems odd that it manifested all at once. Bendix RSA does not have a fuel return. So if the transducer was seeing that flow rate, it was going through the engine.

Understood.  Fuel flow was lower than it should be but not apocalyptically horrific.  

Maybe we will learn more with the cylinders 3 & 4 inspections as well as the fuel & oil lab tests.

[Shadrach]

36 minutes ago, StPeteM20F said:

Understood.  Fuel flow was lower than it should be but not apocalyptically horrific.  

Maybe we will learn more with the cylinders 3 & 4 inspections as well as the fuel & oil lab tests.

It would be helpful to have links to he Savvy data. It’s hard to get a precise look at FF from the pics. Fuel flow may be suboptimal but was it different from the previous flight? 

[carusoam]

+1 for sharing a link to the data…

We can see if anything was showing in prior flights…

Or how quickly the FF changed in any one flight…

 

Great  pics!

That is a lot of stuff…

 

Interesting elbow pics… a touch of rust on the outside as well…a hint that the material is capable of rusting on the inside…

 

One other place to look for rust and dirt…. The fuel necks (where the fuel caps sit) of the older birds, rust on the back side… tiny rust bits make it all the way to the fuel separator, where they collect… down stream of the screen..

fuel necks come in two varieties… stainless steel and the rusty stuff…

Subtle signs rust is getting into the fuel system early on….  Dripping fuel sumps and drains… held open by a tiny spec of rust…

Great report, thanks for sharing the detail!

Best regards,

-a-

[carusoam]

one of the things people do when they have a FF gauge….

As T/O procedure begins….

Throttle is pressed all the way in….

A quick check of three things is in order… ball park numbers only…

1) MP

2) RPM

3) FF

 

Have a plan if any of these three things doesn’t match expectations…

Especially on a short field…

 

PP thoughts only…

Best regards,

 -a-

[A64Pilot]

2 hours ago, Shadrach said:

I’m skeptical of the servo explanation. Temps on the previous flight were ideal. Not saying that servo does not look like shite, but it seems odd that it manifested all at once. Bendix RSA does not have a fuel return. So if the transducer was seeing that flow rate, it was going through the engine.

I’m waiting on fuel analysis too, flight one perfect, flight 2 change tanks and severe detonation on TO has me suspicious, but that’s my nature

[PT20J]

Oops. Looks like the servo inlet screen was removed from the wrong side. It’s supposed to be removed from the inlet side so that any debris remains trapped inside the screen and cannot fall into the servo. 

I’ve accidentally taken off with the mixture leaned and it didn’t detonate. I once asked George Braly if he ever got a normally aspirated engine to detonate with CHT’s below 400 F and he answered, “No at 400. But, at 430 F, then yes. But only marginal detonation and only if the 100LL was lower range or “min-spec” MON 100LL and if the IAT was elevated and the mixture was in the range of 35F ROP back to peak EGT and MAP was near S.L. MAP.” 

So, I would think you would need a combination of high power, high CHT, and lean mixture to get it to detonate. But you noticed the problem “soon after takeoff” so it seems as though this engine started detonating right off the bat.

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[hais]

Glad you found the cause, and thanks for sharing.

When is fuel system supposed to be serviced, at overhaul time? I don't recall seeing the item on 100 hour inspection. 

[Browncbr1]

It seems like the powerflow exhaust and your intake filter together may lower detonation margin.   Higher cht are expected with the powerflow to begin with.   
 

yes, the servo screen is often overlooked and catches all kinds of crap.   It’s amazing how much can accumulate in there.   Keep it clean!

also, crap can collect in the fuel selector and dump debris when switching tanks.   Years ago, I did the solo cup trick and not much came out.    Then I did it again while rapidly switching the fuel selector back and forth.   All kinds of crap came through.   
 

go ahead and rebuild the fuel selector while you’re doing the other fuel system items.   It’s cheap and easy and you’ll be glad you did.

 

[EricJ]

12 hours ago, hais said:

Glad you found the cause, and thanks for sharing.

When is fuel system supposed to be serviced, at overhaul time? I don't recall seeing the item on 100 hour inspection. 

Filters should be checked and cleaned at annual inspection.    FWIW, filter cleaning is Preventive Maintenance and so can be done by owners. 

[Ragsf15e]

2 hours ago, StPeteM20F said:

Savvy Links for incident and pre-incident flights:

https://apps.savvyaviation.com/beta/shared/flight/6277891/274922bd-ebd4-4cc4-a1e6-b424083d3595

https://apps.savvyaviation.com/beta/shared/flight/6277892/0bf216ff-da5b-4952-a776-a084fa141da8

Maybe someone else has luck with them but those links didn’t work for me.  I want to see FF closely through takeoff.

[TheMooneyAnomaly]

13 minutes ago, Ragsf15e said:

Maybe someone else has luck with them but those links didn’t work for me.  I want to see FF closely through takeoff.

Here's the non-beta version - maybe this will work:

https://apps.savvyaviation.com/my-flights/36423/336a77a8-b519-46e4-8a28-f01dac905873

 

[PT20J]

Thanks for the updated link. I went back and looked at the data for a flight where I accidentally took off in my M20J with the mixture leaned. My fuel flow during initial climb from sea level was about 12 gph (yours during the incident was about 15). Normal sea level takeoff fuel flow is around 18 gph. The highest the CHT reached during my climb was 367 F during a 2 min climb before I richened the mixture. My timing is set to 20 BTDC which might give it more detonation margin than one set to 25 degrees. Still, I doubt that you could get that kind of thermal runaway by restricting fuel flow to 15 gph as it takes time for things to heat up enough to get the point of detonation. Your #2 cylinder exceeded redline CHT after a little over 1 minute at an altitude of about 300' AGL. Both cyl 1 and cyl 2 are showing a temperature rise of around 180 F/min. 

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