Engine anomaly - Detonation!

[kortopates]

I thought I'd show an example of an engine anomaly that pilots need to be prepared to take swift action to save their engine cylinder(s). Many pilots have a very nice engine monitor installed but its mere presence doesn't do anything to keep you safe., That's up to the pilot to keep the monitor in their scan and learn as much as they can about how to use them. I know many here have saved themselves multiple times from impending catastrophic damage because they were using their engine monitors as intended. For those learning I offer an an example of severe classic Detonation. The pilot became a Reno Racer with 25" of over boost over redline. Would you have caught this? It only took a little more than minute to cause the catastrophic damage below. CHT6 got as high as 719F the cylinder was over redline for about 90 sec and every cylinder exceeded redline. Redline MAP and RPM are almost identical to a intercooled 231 or 252/Encore.

First the data:

What happens is the overboost creates a very lean condition because the fuel system can't meet the demand of the added boost/air. So we see TIT go over 1700 and then the detonating cylinder EGT go up over 1800F causing its CHT go to 719F before the engine quite entirely - seizing.

From the picture you can see the molten aluminum remains of a piston.

Edited November 21, 2024 by kortopates

[0TreeLemur]

Hey Paul- thanks for sharing this.  Any idea what caused the overboost?  That's crazy.  I've got an old manifold pressure gauge out of a P-51.  I think it is normal max at about 50 in Hg, with a military red line at 60 in case of emergency. 

I'm surprised the head didn't pop off the cylinder.

[1980Mooney]

1 hour ago, kortopates said:

I thought I'd show an example of an engine anomaly that pilots need to be prepared to take swift action to save their engine cylinder(s). Many pilots have a very nice engine monitor installed but its mere presence doesn't do anything to keep you safe., That's up to the pilot to keep the monitor in their scan and learn as much as they can about how to use them. I know many here have saved themselves multiple times from impending catastrophic damage because they were using their engine monitors as intended. For those learning I offer an an example of severe classic Detonation. The pilot became a Reno Racer with 25" of over boost over redline. Would you have caught this? It only took a little more than minute to cause the catastrophic damage below. CHT6 got as high as 719F the cylinder was over redline for about 90 sec and every cylinder exceeded redline. Redline MAP and RPM are almost identical to a intercooled 231 or 252/Encore.

First the data:

What happens is the overboost creates a very lean condition because the fuel system can't meet the demand of the added boost/air. So we see TIT go over 1700 and then the detonating cylinder EGT go up over 1800F causing its CHT go to 719F before the engine quite entirely - seizing.

From the picture you can see the molten aluminum remains of a piston.

The picture you attached is not visible - I tried to view with an iPhone and a PC - but it is just a long alphanumeric string.

[kortopates]

The picture you attached is not visible - I tried to view with an iPhone and a PC - but it is just a long alphanumeric string.

thanks - hopefully fixed now

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[0TreeLemur]

Meltdown.

[kortopates]

Hey Paul- thanks for sharing this.  Any idea what caused the overboost?  That's crazy.  I've got an old manifold pressure gauge out of a P-51.  I think it is normal max at about 50 in Hg, with a military red line at 60 in case of emergency. 
I'm surprised the head didn't pop off the cylinder.

Not with absolute certainty. But there are only a couple possibilities. And for sure, cold oil contributed to or exasperated the situation.


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[802flyer]

Any commentary on the circumstances of the flight? I’d like to hope if it were a routine takeoff from my home field, that I’d notice the extra performance in the seat of my pants pretty early, nevermind the auxiliary warning lamps for my engine monitor flashing in my face. But perhaps a stressful scenario and maybe some alarm fatigue (eg oil pressure always a bit high initially) contributed?

Interesting case. Thanks for sharing.


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[kortopates]

Any commentary on the circumstances of the flight? I’d like to hope if it were a routine takeoff from my home field, that I’d notice the extra performance in the seat of my pants pretty early, nevermind the auxiliary warning lamps for my engine monitor flashing in my face. But perhaps a stressful scenario and maybe some alarm fatigue (eg oil pressure always a bit high initially) contributed?

Interesting case. Thanks for sharing.


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Not from the pilot.
But this was a very short flight. From start up to takeoff was under 4 minutes. At 5 1/2 minutes it was over. The oil didn’t even get warmed up. The silver lining in quickness to failure was that it was fast enough to prevent anyone from getting hurt.
But seeing an engine blow up in 5 1/2 minutes is a new record for me.
I really sympathize for the owner.


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[hais]

We have nice engine monitors. What is preventing the software from annunciating abnormal conditions? Is it regulation or lack of demand/ROI? 

[kortopates]

We have nice engine monitors. What is preventing the software from annunciating abnormal conditions? Is it regulation or lack of demand/ROI? 

It was annunciating alarms for exceeding redlines for MAP as soon as the throttle was pushed in and within seconds for exceeding CHT redlines for every cylinder.

This is good lesson to us all about the need to scan our engine instruments during the takeoff sequence.

With any engine i teach checking oil pressure as soon as you go full power and then with Turbo’s to monitor TIT and abort if it goes over 1450 before taking off.

In cruise using Normalize mode will immediately show EGT and or CHT excursions before alarm limits are exceeded. But the monitor needs to be in your scan.


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[jlunseth]

One of the smartest things I did when the panel was rebuilt in my 231 was to take the avionics shops recommendation to put the JPI930 over on the pilots side, in the scan. I wholeheartedly agree with Paul’s recommendation to check engine parameters during takeoff. Especially the 231 flyers who are in charge of everything about the engine.

[Jim F]

Agreed jlunseth,  I have my JPI830 on the Pilot side right above the throttle quadrant.  It is easy to keep the 830 in my scan.  As Kortopates teaches, on my take off roll my scan is all JPI data in the green, and again mid takeoff roll ~63MPH when I am checking that I have 50% runway remaining, I scan the 830 before liftoff.

[EricJ]

Another thing that's useful to do is wire the engine monitor alarm to a voice annunciator.   My JPI900 alarm is wired to my AV-17, which makes a unique "ping" and then says, "Engine Monitor" whenever it alarms.   When the JPI alarms it puts the alarm item and parameter in big text along the bottom, so whenever that ping goes off it's easy to look at the JPI and see why it alarmed (and I agree, having it in front of you as opposed to on the other side of the panel is very useful).   That ping always makes me cringe a little since it's the engine monitor alarm, but it's generally from the oil being too hot or the oil pressure being a little high on the takeoff roll (if the oil isn't fully up to temp), or something like that.    It did totally pay for itself one day when I forgot to open the cowl flaps on a missed approach and it pinged and annunciated due to cylinder temps getting too high.

I think that sort of thing would make an overboost or TIT overtemp a lot more difficult to miss.    You don't necessarily need an AV-17, as some audio panels allow audio trigger inputs and custom voice annunciations, so that's another route to get the same capability.

[802flyer]

Another thing that's useful to do is wire the engine monitor alarm to a voice annunciator.   My JPI900 alarm is wired to my AV-17, which makes a unique "ping" and then says, "Engine Monitor" whenever it alarms.   When the JPI alarms it puts the alarm item and parameter in big text along the bottom, so whenever that ping goes off it's easy to look at the JPI and see why it alarmed (and I agree, having it in front of you as opposed to on the other side of the panel is very useful).   That ping always makes me cringe a little since it's the engine monitor alarm, but it's generally from the oil being too hot or the oil pressure being a little high on the takeoff roll (if the oil isn't fully up to temp), or something like that.    It did totally pay for itself one day when I forgot to open the cowl flaps on a missed approach and it pinged and annunciated due to cylinder temps getting too high.

I think that sort of thing would make an overboost or TIT overtemp a lot more difficult to miss.    You don't necessarily need an AV-17, as some audio panels allow audio trigger inputs and custom voice annunciations, so that's another route to get the same capability.

Agreed. My MVP-50 has a Voice Annunciator that will ping and then tell you “Check RPM” or whatever parameter is out of range. There’s a hardwired switch to turn it on/off and to acknowledge the message to make it quiet. Between that and the auxiliary Caution and Warning lights just above my PFD, it’s hard to miss when the monitor is upset.

All of that said, it can be a bit annoying as I too will get yellow-range oil pressure briefly during the first take off of the day, and it warns me when my RPM is in the avoid-continuous range when transitioning to land. So I think my greatest risk in missing something will be due to alarm fatigue rather than lack of engine monitor (literal) bells and whistles. Whenever it lights up, I try my best to scan the whole monitor screen for other anomalies; the voice annunciation is helpful to recognize atypical alarms (I have the EI connectors that like to loosen up occasionally, and have been startled in cruise by a “check cylinder head temperature” alert when one decides to go intermittent). Hopefully if something bad happens I’ll have the presence of mind to look carefully and catch it quickly.


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[hais]

On 11/21/2024 at 10:00 PM, kortopates said:

It was annunciating alarms for exceeding redlines for MAP as soon as the throttle was pushed in and within seconds for exceeding CHT redlines for every cylinder.

This is good lesson to us all about the need to scan our engine instruments during the takeoff sequence.

With any engine i teach checking oil pressure as soon as you go full power and then with Turbo’s to monitor TIT and abort if it goes over 1450 before taking off.

In cruise using Normalize mode will immediately show EGT and or CHT excursions before alarm limits are exceeded. But the monitor needs to be in your scan.


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There are two factors that would be an improvement I think.

First is that, an algorithm would pick up a condition sooner than an eye scan would, and offer a suggestion quicker than a trained person can reason out the situation.

Second, the annunciator could be made to be drastically different from normal display. Think about the old school warning light. Quite effective when it comes on, compared to picking up changes in a somewhat busy display.

[IvanP]

JPI monitors have optional warning light that can be programmed to come on when the monitor detects certain anomalies (many programming options). This can be beneficial for installations that have the main monitor screen outside ofthe pilot's scan. The warning light can be installed anywhere - mine is front and center in my view of my panel. 

[0TreeLemur]

On 11/22/2024 at 12:00 AM, kortopates said:

But the monitor needs to be in your scan.