enginehistory.org

[rwahlgren]

This guy goes through the report.
https://www.youtube.com/watch?v=1HNsQuLrOqg

The comments about the cylinder corrosion? Very likely from what was used to put out the fire. There was no mention about fire or heat damage to the magneto's, that could affect the test results.

[kmccutcheon]

[mksmith]

I'm skeptical whether or not that amount of corrosion would have been caused at the scene during the initial and later recovery efforts. That said however, the investigative teardown occurred Feb 11-20, four months later so when these pictures were taken, who knows what the condition would have been at the time of the accident.

You can find the information here:

https://data.ntsb.gov/Docket?ProjectID=100356

Item 37 Page 69


On the other hand, given all the other signs of poor maintenance. Both of #4's magnetos P-leads were separated from the housing, the left one being removed completely and grounded to the housing rendering it inoperative, I imagine this should have been caught during a mag check at run up.
_________________
Mike Smith

[rwahlgren]

https://www.youtube.com/watch?v=9x1TCMftngU
Start At 11:46


I do not agree with these guys.
I like how he says no damage to the cylinder, he should look again.
I didn't see signs of detonation, did they look at the piston?
Don't they know even a connecting rod bending hydraulic lock usually will not split the head. At 12:30 its the force that distorted the cylinder that split the head. He says when you look at the metallurgy of it??
Sorry guys the NTSB was correct on this.

[kmccutcheon]

[rwahlgren]

Only piston I could barley see was the one in the cylinder, thanks for the links.
The power plant report is great, though the picture quality should be much better. How to find more of these types of reports?

Photo number 80, Engine #3 cylinder #4 ? Detonation? I guess if the engine was running when the prop suddenly hit obstructions then maybe there could have been for a few seconds or so. Continuous running with detonation usually leaves pits, and would clean the combustion space better. What would be the reason for only 1 or 2 cylinders only to be involved? There is a lot of carbon and lead Bromide or what ever on the pistons. Look at photo 64 corrosion on the upper skirt area.
Photo 112 shows rusty top ring, and piston similar to #4. Photo 113 in the cylinder shows rusting. So all white colors could be corrosion, photos only say so much. Photo 114 rust again and corroded push rod tube.
Finally on page 67 they mention corrosion. Photo 119 and how come they don't say detonation with this clean top piston that is similar to the other?
Page 86 and no mention of the missing propeller shaft? How did they rotate it? Photo 157 No mention of detonation here similar to photo 80.
What happened here? Photo 169 shows white on piston top and 170 its gone? Strange inconsistency.
The comments for photo 172, yellow paint on face of the valve? How do they see the face with it installed? Nomenclature problems?
Detonation and yellow exhaust valve face paint has me wondering.

[rwahlgren]

Is this report the final report on the engines? How come only the 2? Since the plane was barely flying you would think an inspection on all the engines would be in order.
I was under the impression that an investigation for a plane crash engine would be a bit more thorough. There is no mention of checking E gap, nor magneto to crankshaft timing especially when they mention possible detonation. There are more accurate ways to check the point gap, that removes the human element of feel, that I think should have been used, and was the shaft checked for play? There is no mention about the propshaft condition on one of the engines that looks over heated in the photo.
It is obvious that good maintenance was very lacking with some of the findings in this report. The picture quality is horrible.
I expected it to be a bit more professional considering the source.

[kmccutcheon]

[rwahlgren]

Yes that is why I was pointing out the corrosion and rust, from sitting after being watered down or what ever is used to put out the fire. So when they mention white color on the piston etc we have no real idea what it is in a photo.
I just thought the photos especially some of the close up out of focus ones should have been better since the outfit taking them has almost unlimited dollars to afford a better quality camera, especially for such important tasks as aircraft accident investigations.
All those detonation causes mentioned okay. But they would cause long term detonation problems, with the lack of major pitting and or burned edges the event would have been short term or very intermittent.
It would be nice to see more of these kinds of reports.
And pardon the pun, what has me on the antidetonate is that video where they claimed detonation blew up the cylinder head.

[rwahlgren]

Volume 4, Number 4 Torque Meter magazine.
ATDC by Kevin Cameron

Article is about DETONATION AND PREIGNITION

On the continued page 18
"Light deto leaves the edges of pistons looking slightly sand-blasted. Heavier deto splashes off aluminum which can sometimes be seen as something like gray cigarette ash specks on the spark plug insulator."

Just thought this was on topic for this discussion.

[rwahlgren]

In doing some study on detonation, I found information that crevice space could be ripe for helping detonation. Since in the crevice space possible stagnate air fuel mixture could be available and not readily ignited from normal ignition flame. Crevice space would be the area around especially the top compression ring. And this maybe why that area and piston edges are so susceptible to the attack from detonation.