Rght out of the gate? Seriously???

[EricJ]

1 hour ago, Bolter said:

I think this is a scam site.  They collected public info and put it into a page full of dangerous links and phishing pop ups.  I do not recommend clicking on it.  

My antivirus system freaked out when I clicked on that and blocked it, so I would concur, don't click on it.

[Conrad]

1 hour ago, Bolter said:

I think this is a scam site.

Sorry about that! I removed the link.

[Conrad]

I've also been thinking pretty hard about this accident. I'm an engineer, and I know I have more context than anyone else does about what happened here in part because I knew the plane and its maintenance history intimately.

The most telling clue of the whole investigation won't be found in the official report, I think, but on this forum. Fred described removing a clod of some major contaminant from one of the fuel tanks and he he poses a chilling question here that he never answers. What was it? And he also tells us what it was: it was dirt, or once it dried: dust. How did that get in there...? Cloudy fuel, dirt in the tanks, none of that tracks with my experience of this plane. Time appears to have changed something. A living thing, like an ant or a wasp, could explain it perhaps. The plane was in an open-air T hangar right next to a cornfield. If a tiny animal of some sort brought dirt into the tank there might have been a lot more of it on the inside than anyone would have reason to think there might be... And if they got most of it but not all of it, the post-crash fire could easily have destroyed the rest of the evidence of such a thing.

[Conrad]

On 10/13/2025 at 6:54 AM, Freddb34 said:

An inspection of the fuel tanks revealed a considerable amount of build up in the left tank (right tank was clean).  Plan is to remove the top panel and remove all of the debris (it's not metal or sealant...not sure what it is).  But once that's cleaned out, the AP/IA will test fly it and hopefully by Wednesday I can pick it up.

On 10/22/2025 at 5:06 AM, Freddb34 said:

Thanks and yes. There was some sediment built up into clumps that once the tank was completely drained and dried out, turned into a silty powder.  They got it all out by flushing it several times until it was cleaned.  Just happy to have my plane back and bring it south.  

[Jsno]

There is a YouTube article on this.  Possible fuel pump failure but since it was damaged in the fire it could not be determined.  Sounds plausible to me.

[201er]

On 11/20/2025 at 7:24 PM, Conrad said:

The most telling clue of the whole investigation won't be found in the official report, I think, but on this forum. Fred described removing a clod of some major contaminant from one of the fuel tanks and he he poses a chilling question here that he never answers. What was it?

Is there any way that really old avgas can harden?

Not sure if this is even real, but recently saw this about supposedly 50 year old jet fuel turning to jelly:

 

[N201MKTurbo]

14 minutes ago, 201er said:

Is there any way that really old avgas can harden?

Not sure if this is even real, but recently saw this about supposedly 50 year old jet fuel turning to jelly:

 

When I extracted the 56 Cessna I had, the fuel in it was 10 years old. It started right up with it. It was very blue. A lot of the avgas had evaporated and concentrated the blue dye. Probably concentrated the TEL too. Avgas is almost pure alkylate. If it evaporates you just get less of it, it doesn’t change properties. Car gas, on the other hand is a witches brew of different stuff with very different volatility. So, when it evaporates, it does so very unevenly. The most volatile stuff goes first. So it changes properties rather quickly. 
 

Jet fuel will oxidize and form gum over time. When I was working on cruise missile fueling systems, they measured the gum content of their fuel storage tanks every day. 

[Lax291]

Good morning and hope everyone had a great Thanksgiving!  Having met Fred a few weeks before his accident, I’ve been following this closely. Does anyone have any better idea of what happened, any more information that’s come out to help prove/disprove a hypothesis? 
 

[Aaviationist]

3 hours ago, Lax291 said:

Good morning and hope everyone had a great Thanksgiving!  Having met Fred a few weeks before his accident, I’ve been following this closely. Does anyone have any better idea of what happened, any more information that’s come out to help prove/disprove a hypothesis? 
 

Have you tried reading the thread you posted in or any of the preliminary reports in it?

[LANCECASPER]

3 hours ago, Lax291 said:

Good morning and hope everyone had a great Thanksgiving!  Having met Fred a few weeks before his accident, I’ve been following this closely. Does anyone have any better idea of what happened, any more information that’s come out to help prove/disprove a hypothesis? 
 

A few pages back on this post is the preliminary report.

[Lax291]

9 hours ago, Aaviationist said:

Have you tried reading the thread you posted in or any of the preliminary reports in it?

Why would I do that when I can bother you about it? But in all seriousness, yes and it seems like there was no definitive smoking gun. I'm curious if any new information might have come to light to help zero in on what might have happened. 

Maybe I missed that in the threads?

[Jackk]

On 11/20/2025 at 7:24 PM, Conrad said:

I've also been thinking pretty hard about this accident. I'm an engineer, and I know I have more context than anyone else does about what happened here in part because I knew the plane and its maintenance history intimately.

The most telling clue of the whole investigation won't be found in the official report, I think, but on this forum. Fred described removing a clod of some major contaminant from one of the fuel tanks and he he poses a chilling question here that he never answers. What was it? And he also tells us what it was: it was dirt, or once it dried: dust. How did that get in there...? Cloudy fuel, dirt in the tanks, none of that tracks with my experience of this plane. Time appears to have changed something. A living thing, like an ant or a wasp, could explain it perhaps. The plane was in an open-air T hangar right next to a cornfield. If a tiny animal of some sort brought dirt into the tank there might have been a lot more of it on the inside than anyone would have reason to think there might be... And if they got most of it but not all of it, the post-crash fire could easily have destroyed the rest of the evidence of such a thing.

 Huh?

If you knew the plane and its maintenance history better than anyone why can’t you answer that question yourself?  

 I’m not a engineer and I can also say removing a giant chunk of gunk from fuel tank and having the plane crash shortly after might be tied together too

[LANCECASPER]

8 hours ago, Lax291 said:

Why would I do that when I can bother you about it? But in all seriousness, yes and it seems like there was no definitive smoking gun. I'm curious if any new information might have come to light to help zero in on what might have happened. 

Maybe I missed that in the threads?

Not sure where the new information would come from in this long period between getting the preliminary report and when the final report comes out.

In the final report it will be interesting to hear if they interview the first CFI that flew with him early in October that helped get the airplane down safely that first day. After everything that happened did he refuse to fly the airplane back to Florida with him? It will also be interesting to hear all of the details of what the A & P has to say was done in the weeks between the first time @Freddb34 flew it and the day of the accident. After test flying it was he completely confident in the airplane or had he recommended sending off the fuel system or any other remedies? How much information was shared with the new CFI that survived, but came in just the night before the accident flight? If they interview the previous owner, the SWA pilot, how many hours had he flown the airplane and how times had the power cut out for him? There are a lot of unanswered questions. 

[Fritz1]

story of a systemic failure, owner tried everything he knew how to resurrect a vintage piece of machinery that would cost close to $1M to produce new, a lot to be learned, the question I am asking myself is what can be done so the frequency of this kind of systemic failure does not increase but decrease, no simple answer

[N201MKTurbo]

So, for the engine to completely quit, it must lose spark, air or fuel. That assumes all the mechanical parts still work. The mechanical parts are easy to examine after the worst crash and fire. Things like cranks, cams and gears. Spark has the most redundancy with two mags and eight spark plugs. Very unlikely they all quit at the same time. Air induction doesn’t have many ways for a complete failure. About the only thing that could do it is a collapse of the induction boot. I would hope that would have been caught after the first incident. That leaves fuel. The RSA fuel injection system requires pressurized fuel at its inlet. There wasn’t a lot of discussion about fuel pressure from the OP, I wish there was. The fuel pressure gauge should be the first thing to look at. Other than having water in place of fuel, the fuel pressure gauge will verify the operation of everything upstream of the servo. The servo itself is unlikely to be intermittent and completely cut off fuel flow suddenly. Anything I can think of inside the servo that would cut off fuel flow, wouldn’t get better by itself. Anything downstream of the servo inlet would require some kind of clog. It’s unlikely that anything that could cause a clog could get past the finger screen. A clogged finger screen would cause a lack of fuel pressure. And it wouldn’t get better without cleaning it. And it should be easily seen in a post crash investigation.

So, what can cause a loss of fuel pressure? 
1. No fuel available to the fuel pumps.

2. A clog upstream of the fuel pumps.

3. Defective fuel pump.

4. A leak upstream of the fuel pumps.

5. A leak down stream of the fuel pumps.

6. A clog down stream of the fuel pumps.

As you can see, there are a lot of things that can cause a loss of fuel pressure. There is also a lot of redundancy. We have redundant fuel tanks and redundant fuel pumps. If the fuel pressure gauge indicates pressure, about the only thing that can cause the engine to quit is water in the fuel and switching tanks should be your first move. It takes about 10 seconds for fuel from the other tank to make it to the cylinders, which can seem like an eternity. If there was water in the fuel, it can short out the spark plugs and it can take a bit for the water to be either blown out of the cylinders or evaporate so the plugs can fire. In this incident, it is very unlikely there was water in the tanks after all the work that was done. If there is a lack of fuel pressure, there are only two things you can do, switch tanks and turn on the boost pump.

[PT20J]

The mechanical fuel pump has two poppet valves. If contamination somehow got to the pump, it could hold one of the valves open and defeat the pump. But contaminants would have to get past the gascolator screen unless the aircraft had an older Dukes aux pump and SBM20-222B to add a filter after the aux pump had not been complied with and the Dukes fuel pump was failing.

[Jackk]

5 hours ago, Fritz1 said:

story of a systemic failure, owner tried everything he knew how to resurrect a vintage piece of machinery that would cost close to $1M to produce new, a lot to be learned, the question I am asking myself is what can be done so the frequency of this kind of systemic failure does not increase but decrease, no simple answer

 I don’t think it’s that dramatic, fuel contaminant is fuel contamination.

 

 If I pulled a chunk of gunk out of a tank that was that significant, it’s be purging the tank, all the filters, all the lines, carb, etc. 

 

 I’d also probably save/send the gunk out to have it analyzed as to what it was 

 

 different path I’d take if was a mud dauber nest vs bits of sealant/hose that broke down 

Edited November 30 by Jackk

[EricJ]

When my servo failed it was intermittent.    During the last failure after we landed it would barely idle, and just made enough power for us to taxi to a parking spot.    We ran it there for a while to try to see what we could get it to do, and it did come back and run, even full throttle, for a bit, then quit again.   It did that a couple times.   We definitely weren't going to fly it again, but there are apparently mechanisms by which the diaphragms and rods can get jammed and then unjam, or something.   Contamination can get into the servo through the fuel path, which is heavily filtered, or through the impact pressure tubes, which is usually filtered but not on a Mooney with the ram air door open.

 

[DCarlton]

On 11/27/2025 at 12:20 PM, 201er said:

Is there any way that really old avgas can harden?

Not sure if this is even real, but recently saw this about supposedly 50 year old jet fuel turning to jelly:

 

I believe the process is called polymerization.  I encountered this when working on an old Vietnam era weapon system back in the late 80s.  It does happen with some fuels but I’m guessing it wasn’t a factor.  I’ll bet there’s a chemical engineer on Mooneyspace that can explain it.  

[N201MKTurbo]

https://ntrs.nasa.gov/api/citations/19970025575/downloads/19970025575.pdf

This is a good article about the chemistry of gum and deposit formation.

 

[1980Mooney]

Why is everyone talking about "giant chunks of gunk"?

On Oct. 22 he said here:

"There was some sediment built up into clumps that once the tank was completely drained and dried out, turned into a silty powder.  They got it all out by flushing it several times until it was cleaned.  Just happy to have my plane back and bring it south. " 

[N201MKTurbo]

48 minutes ago, 1980Mooney said:

Why is everyone talking about "giant chunks of gunk"?

On Oct. 22 he said here:

"There was some sediment built up into clumps that once the tank was completely drained and dried out, turned into a silty powder.  They got it all out by flushing it several times until it was cleaned.  Just happy to have my plane back and bring it south. " 

Because the thread went off on a tangent that has nothing to do with the original post. That happens around here.

I suppose it is because the OP found crud in his tank. Even though the crud was cleaned out. It seems the OPs crud was just dirt, not any kind of gunk, gum or varnish.

[Shadrach]

18 hours ago, EricJ said:

When my servo failed it was intermittent.    During the last failure after we landed it would barely idle, and just made enough power for us to taxi to a parking spot.    We ran it there for a while to try to see what we could get it to do, and it did come back and run, even full throttle, for a bit, then quit again.   It did that a couple times.   We definitely weren't going to fly it again, but there are apparently mechanisms by which the diaphragms and rods can get jammed and then unjam, or something.   Contamination can get into the servo through the fuel path, which is heavily filtered, or through the impact pressure tubes, which is usually filtered but not on a Mooney with the ram air door open.

 

There are small orifices that can become blocked by debris when fuel is flowing/under pressure. When the flow/pressure is removed, the debris dislodges from the orifice and free floats in the servo until flow/pressure is reintroduced. The impact tubes are not on the “wet” side of of the diaphragm but blocking them will cause the mixture to lean. When my servo was rebuilt, I was told that they found debris in the tubes but none were blocked. I never noticed it on the JPI, but I did not have a baseline for comparison. I knew that I wanted more fuel on takeoff off as my EGTs were always high 1200° to low 1300° range, meaning I was only ~200° ROP at best on take off.  I asked to have the servo set as rich as possible within spec. When I got the servo back, all EGT‘s were 1150° to 1180° on takeoff. Over time, takeoff EGT’s have slowly increased to 1180° to 1230°. I’m wondering if the impact tubes have collected obstructions over the years, causing my engine to run slightly leaner than it did right after servo overhaul. I do use the RAM air in “clear air“ starting  ~500 feet AGL in winter; it remains closed until above 3000 during bug season.

I can’t say for sure, but it seems to me that a failure like Fred’s would require an intermittent blockage on the wet side of the servo blocking the outflow to the divider.
Debris in the intake tubes would likely show up as elevated EGT’s and CHT’s from an overly lean mixture.

[N201MKTurbo]

We can hope the NTSB will have the servo inspected. 
 

I bet they are reading this thread BTW.

[Ragsf15e]

1 hour ago, N201MKTurbo said:

We can hope the NTSB will have the servo inspected. 
 

I bet they are reading this thread BTW.

I hope they put a pretty good effort into it instead of just saying it was all too damaged in the fire and they can’t tell.  I think it could potentially save lives in the future to know what really happened.