Borescope

Tom-D said:
good,, because I've never seen a borescope fix anything.
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Agree, but if it ain’t broke, don’t fix it. And a boroscope sometimes can determine that.
 
Even the crappy little Depstech one can be useful to poke in behind panels and at valve seats. The VA400 is on my xmas list though.... assuming I don't buy it sooner.
 
Lance F said:
Agree, but if it ain’t broke, don’t fix it. And a boroscope sometimes can determine that.
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If you have reason to poke a borescope in, you have problems already.
all you are doing to verifying that it is messed up.
 
Tom-D said:
If you have reason to poke a borescope in, you have problems already.
all you are doing to verifying that it is messed up.
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Kind of the point of the boroscope inspection, isn't it? Why not make use of new(ish) technology to guide the decision process? And why not use it at each annual to document the on-going health of the valves?

Do people only get their blood pressure checked after a heart attack or checked during doctor visits? I have a long record of my BP. Same for the borescope inspections I do at work. I can go (and have gone) back to old pics to compare. Extensions are pure paperwork, as I have a buttload of data to base my "inspection" on.
 
Tom-D said:
If you have reason to poke a borescope in, you have problems already.
all you are doing to verifying that it is messed up.
Click to expand...
I thought one could see things like a valve starting to go bad, before it fails.
See here:
https://www.aopa.org/-/media/Files/...ety/14FN0000-ASI-Valve-Safey-Poster_Final.pdf
https://www.aopa.org/training-and-safety/air-safety-institute/valve-safety
In the poster, a valve looking like images 1,2, or 3 could have the rocker arm adjusted, no?
 
JAWS said:
Kind of the point of the boroscope inspection, isn't it? Why not make use of new(ish) technology to guide the decision process? And why not use it at each annual to document the on-going health of the valves?

Do people only get their blood pressure checked after a heart attack or checked during doctor visits? I have a long record of my BP. Same for the borescope inspections I do at work. I can go (and have gone) back to old pics to compare. Extensions are pure paperwork, as I have a buttload of data to base my "inspection" on.
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Is it a boat-load? When did we switch that to butt-load?! I say that too. LMAO.
 
Cap'n Jack said:
I thought one could see things like a valve starting to go bad, before it fails.
See here:
https://www.aopa.org/-/media/Files/...ety/14FN0000-ASI-Valve-Safey-Poster_Final.pdf
https://www.aopa.org/training-and-safety/air-safety-institute/valve-safety
In the poster, a valve looking like images 1,2, or 3 could have the rocker arm adjusted, no?
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Of course but how bad is too bad? It's the degree leakage that quantifies bad. A picture is superfluous. Just pull the %&*%%#%^ cylinder if valve leakage starts under 60/80 and FIX IT.
 
Snowmass said:
Of course but how bad is too bad? It's the degree leakage that quantifies bad. A picture is superfluous. Just pull the %&*%%#%^ cylinder if valve leakage starts under 60/80 and FIX IT.
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there is guidance by both manufacturers
 
Tom-D said:
there is guidance by both manufacturers
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They do indeed. And at least at the TCM Service Bulletin level require a boroscope inspection.
Have a nice day everyone.
 
Lance F said:
They do indeed. And at least at the TCM Service Bulletin level require a boroscope inspection.
Have a nice day everyone.
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Service bulletin -- ???
78/80 PSI Are you going to continue?
 
Cap'n Jack said:
Does the valve start to leak before the off-center coloration starts? (Image 1 in link below).
It also seems easier to remove a plug and get a picture than to do the leakage test.
https://www.aopa.org/-/media/Files/...ety/14FN0000-ASI-Valve-Safey-Poster_Final.pdf
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I’m gonna take an educated guess here and say yes, but how long before may be trivial (or not).

Discoloring (let’s call it non-uniform coloration) is caused by inconsistent heat build up in the valve. Problematic heat buildup is caused by differing valve-to-seat contact around the circumference. Valve-to-seat contact is how the valve sheds its heat (to the seat then head, then atmosphere).

How did the seat or valve lose consistent contact? Lack of rotation? Poor rebuild? Too much heat from the guy running the red (mixture) or black (MP) knob?

It’s maybe a chicken or egg question, with maybe the answer being that for all intents and purposes that they are simultaneous (in the maintenance interval timeframe).

-No A&P, but “mad skilz”, lol - I defer to the great A&Ps here who always provide good internet guidance to me since I’ve been here on POA (you know who you are and in the spirit of Thanksgiving, I’m grateful).
 
I'll continue to try to catch problems before they become something can't be repaired, If that means pulling a cylinder, so be it.
 
Tom-D said:
I'll continue to try to catch problems before they become something can't be repaired, If that means pulling a cylinder, so be it.
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Tom....the borescope is a visual check that finds problems....before you have to remove a cylinder.
 
Should I tell my AP to change my valve rotators? I have a O-200 with about 850 hours. No issues, but if they are cheap and easy to do, is it worth it?
 
I see rotocoil parts for the O-200, so some must have them. I’ll check to see what cylinders I have in the logs for the overhaul.
 
I think this whole issue depends on understanding cause and effect. It is poor seat contact that causes exhaust gas leakage which causes valve burning and discoloration. You will not have discoloration prior to leakage. Why would you? So it is the compression test that that is the early warning indicator of valve burning not visa-versa.
 
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