Why aren't chip detectors used in piston GA aircraft?

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T Bird

Pre-takeoff checklist
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T Bird
Just learned about these and on the surface they seem like they could be a relatively cheap and easy safety addition to single engine piston aircraft, giving pilot an earlier heads up of possible impending engine failure. There's probably some easy answer here that I just don't know but I've had difficulty finding more information. These are pretty common in helicopters and many turbine aircraft engines but can't find any cases of them being installed in piston engines. Anyone know the reason(s)?
 
Just had one (xmsn) last week with a patient on board. :( I think with pistons they just don’t have the extensive gearing like turbines to warrant the extra cost. Especially turbine helicopters.
 
I think you'd get a lot of false alarms in a piston engine. Especially as the engine ages, but before it starts making visible metal. A lot more parts sliding against each other compared to a turbine or helicopter gearbox.
 
T Bird said:
Anyone know the reason(s)?
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Too much metal and debris in the oil to be useful. They've been developed and used in the past but caused more problems than they indicated. However, even on turbine engine application you can still get nuisance indications due to "fuzz" and other anomalies, which is why they developed burner chips plugs that would "burn" off the debris and extinguish the chip light in flight.
 
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One of the STC’d firewall-mounted oil filter mods used to offer a chip detector option. I doubt it ever did much good for anyone that used it. I bought one of their filter relocation kits and never installed it. Gave it away after having it on the shelf for 10 years. Airplane owners will pay good money for all kinds of useless crap.
 
Bell206 said:
Too much metal and debris in the oil to be useful. They've been developed and used in the past but caused more problems than they indicated. However, even on turbine engine application you can still get nuisance indications due to "fuzz" and other anomalies, which is why they developed burner chips plugs that would "burn" off the debris and extinguish the chip light in flight.
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Yeah wish we had fuzz burn. Probably would’ve eliminated the one (less 2 mm) I had last week.
 
By the time you get a "chip" large enough to detect with a system cheap enough to put on typical GA airplane the engine will already be toast. Chip detectors on turbine engines are great for finding larger items like a piece coming off one of the teeth in the gearbox or something in the lubrication system starting to self destruct and catastrophically fail. They aren't going to find small particles coming from piston walls as they wear down over time. You will get much more value out of cutting open and inspecting the oil filter as well as sending the oil out for analysis at each change and watching for trends.
 
you mean like the chips they use to find lost dogs?
 
kmacht said:
They aren't going to find small particles coming from piston walls as they wear down over time.
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You’ll find its those small, fine metal particles that will mix with oil/carbon and accumulate on the chip plug contacts, bridging the gap. This is why chip plugs don’t really work on recip engines in most cases due to the volume of minute metal particles in the oil.

While some “large” pieces do get caught on the plug on occasion, its mostly small chips, flakes, and slivers that are found and addressed. For example, on a RR C30 turbine any chip or flake over 1/32” in diameter or more than 4 slivers of metal and you could be pulling the engine or module out of service.

The whole purpose of chip plugs is to detect an impending failure vs an outright failure. Unfortunately, there have been catastrophic turbine failures where the chip light illuminated quickly followed by a loud explosion or worse only a loud explosion with no light.
 
Funny thing, only time I’ve ever flown in a Huey was a chip I got in a Black Hawk. 3,700 hrs and only one chip. FLATIRON came to pick us up and got to experience the whoop whoop of the Huey with doors open. They got Lakotas now. :confused:
 
Checkout_my_Six said:
would you shut down the engine on an alert?
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It depends on the engine. Years ago with the Lycoming LTS-101 series turbine and their issues, if the chip light even flickered you were required to shut down the engine. It got so bad at one point due to bearing failures, they rerouted the turbine governor control lines (Py) internally into the gearbox and installed a cutter on the main turbine shaft. So if a #2 bearing failed which would cause the entire turbine blade/shaft assy to move aft, the cutter would cut the Py line and decel the engine if you missed the chip light flicker.
 
No....I would not shut down my GA engine....so the point is moot. Then if you make it down....you can cut the filter and determine the cause of the failure.
;)
 
EvilEagle said:
T-28’s have a chip light (most at least) and those guys swear by them. We don’t use them on the R-1340 in the T6 but we do on both the B24 and B29
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Interesting, is there something about a radial engine that makes a chip detector more feasible than a typical flat engine? Would they not have the same kind of "false alarms" that several have discussed in this thread?

Checkout_my_Six said:
would you shut down the engine on an alert?
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No but in theory it could give you more time to handle the impending failure. I imagine it being something where the light coming on could cause you to abort a takeoff, immediately identify and turn towards nearest airport, etc. The false alarm aspect makes sense, but I wonder if that could possibly be accounted for with engineering. Any potential indication that your engine is about to fail I think could ultimately save lives, even if it's just an extra few minutes.
 
T Bird said:
Interesting, is there something about a radial engine that makes a chip detector more feasible than a typical flat engine? Would they not have the same kind of "false alarms" that several have discussed in this thread?
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I'm not sure. We've had several issues with them in the B-24 and have put several on/off MEL for various faults over the years. I'm not a T-28 guy so I just learned recently that they use them.
 
T Bird said:
Interesting, is there something about a radial engine that makes a chip detector more feasible than a typical flat engine? Would they not have the same kind of "false alarms" that several have discussed in this thread?


No but in theory it could give you more time to handle the impending failure. I imagine it being something where the light coming on could cause you to abort a takeoff, immediately identify and turn towards nearest airport, etc. The false alarm aspect makes sense, but I wonder if that could possibly be accounted for with engineering. Any potential indication that your engine is about to fail I think could ultimately save lives, even if it's just an extra few minutes.
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Just monitor your temps....that will be just as effective. ;)
 
T Bird said:
Interesting, is there something about a radial engine that makes a chip detector more feasible than a typical flat engine? Would they not have the same kind of "false alarms" that several have discussed in this thread?
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Keep in mind, there are several different types of chip detectors, but mainly electric, which give an indication in the cockpit, and manual which requires physically removing the plug to check for metal. The only ones I've seen on radials were the manual type that had internal superchargers so no false alarms while flying. But if that manual plug was not the quick-discount type then you would tend lose oil while checking for metal. Also the type of oil system design can affect if a chip detector would be feasible as well.
 
AV8R_87 said:
Interesting, I thought fuzz burners were pretty much standard equipment in the industry by now.
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Well @Bell206 could probably give an accurate percentage for the heli industry. I can tell you our 407s and 135s don’t have it. Had it on the Black Hawk xmsn, input mod and tail gear box (30 sec delay) but not in the engine oil. It think it’s a good feature though to eliminate particles that don’t indicate a major failure and preventing needless land ASAP landings.
 
Velocity173 said:
could probably give an accurate percentage for the heli industry.
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As I recall the percentage was more operator-centric than anything else. However, a number of operators tended to follow the old Army studies that adding a finer filtration to the oil system provided more benefits than a fuzz burner system and went that route.

Plus there have been instances where the use of the fuzz-burning portion of the detector system was prohibited after several high-profile failures. Which in turn influenced certain industry customers to not want them used as well.
 
I have an STC’d chip detector on my Bo, and it has never given me a nuisance alert (around 1200 hours). I’m glad to have it.
 
How quickly an engine unravels from chip detection to sudden stoppage or significant power loss probably varies depending on the mode of engine failing. Fuzz induced detection will be a slower death than an actual chip of metal that sets the detector off, if anything bad even happens at all. I wouldn’t mind it, it’s another data point and the risk of false positives or negatives is worth it.
 
SCCutler said:
I have an STC’d chip detector on my Bo, and it has never given me a nuisance alert (around 1200 hours). I’m glad to have it.
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Interesting -- curious what was the cost to install that? Or did you buy it with it already installed?
 
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