[Del Herring]

Hi folks,
I've been coming to these forums and reading for years in anticipation of some day being able to put together my own RV, and just out of curiosity. I'm currently an aerospace engineering student/professional, and for one of our courses we were asked to develop an aviation related system of our choice. Since I've long been interested in general aviation and more recently experimental aviation, we came up with the idea to design an aircraft health-monitoring system for the general aviation market. Who knows, if the project goes well, maybe we'll actually be able to make it some day, for now we're still conceptual.

For the project, I'd love to get some input from you guys due to your experience not just in aviation, but in actually putting together and maintaining your aircraft. My general idea is something non-intrusive, that would use existing, or potentially new systems to monitor and log information about the aircraft and let pilots know when a problem is starting before it becomes catastrophic. We'd hope to improve safety and reliability of aircraft at the lowest cost.

So, if you could have the system however you wanted, what would be most important to you? What are some of the most common aircraft mechanical/electrical problems that people experience? I'm looking for any input you guys and gals have on this. Let me know what you would want if the system was built just for you.

I appreciate any input any of y'all can give. It'll help us out with school, and maybe it'll be the start of something useful for the experimental community down the road.

Thanks!

 

[rleffler]

Alex,

Email me with your location. If you are in central Ohio, I can introduce you to quite a few folks the fly RVs.

DLZ EAA VAA 27 has a meeting Wednesday evening at 7:30. The meeting topic is WWI technology advances in aviation. There will be at least a half dozen v flyers and builders there.

Bob

 

[vluvelin]

electronic project as i understand right?

Hi


recently i was checking my prop balance and playing with spectrum analysis and spectrum monitoring software
would be nice to have system that can actually be on board at all time and monitor spectrum and identify problems to come in in at-list couple of hours
also when problem suspected by system pilot can switch his audio panel to engine mike ( electronic equivalent of stethoscope)to listen to engine

if you need more details on this let me know by PM

 

[Del Herring]

Thanks for the replies.

vluvelin, that's the kind of input I'm looking for. I need to do a little reading up on spectrum analysis before I'll be able to ask any intelligent questions, but those ideas sound feasible.

rleffler, I'll shoot you an e-mail.

 

[aeroaddict]

Most health monitoring systems utilize accelerometers that capture vibration frequencies. Once a part or system is characterized then algorithms can be developed. The realtime vibration profile is then recorded and periodically analyzed for limit violations. Ideally this would allow part life limit extensions (which is where the $$ is) or, of course, detection of imminent failure.

The health monitoring systems I have seen are for helicopters; a wonderful vibration environment.

For aircraft, I think one would need to understand the common (and expensive) failure modes, then develop detection methods for that failure mode. There must be FAA data that has information on aircraft maintenance and from that, one could determine common maintenance issues/failures per type of aircraft; piston (single/multi), turbine, complex, .......

For a lowly GA pilot like myself, the most critical system for me is propulsion; that prop needs to keep turning. To keep the windmill turning, the internal combustion engine needs to work flawlessly. For a GA single engine health monitoring system, it is a matter of monitoring critical failure modes of a internal combustion engine and associated support systems; fuel, electrical, prop, lubrication, .....

Sorry for the long answer and you probably already knew this stuff.

Dan

 

[vluvelin]

Vibration spectrum in home builts

Maybe it is made for helicopter health monitoring system but didn't see one in Dynon or GRT unless i am looking in the wrong place.

from what i know engine problems are starting slowly but progressing fast
by the time human is able to fill it it may be too late but constant spectrum analysis software can detect it really quick and notify pilot to pay attention

also from my automotive background i like to use stethoscope on the engine
you can hear every knock and slap if you know how it sounds.

aero-engines have much more vibration then automotive and bad lifter adds to the picture. Some one can start tuning nozles when in reality he needs to change lifter

sorry for my poor english

 

[gammaxy]

This is probably slightly unrelated, but recently I've been building a dynamic propeller balancer using the Tinyduino platform and accelerometers, a laser tachometer, and Android phone for signal processing and display.

Here, I'm testing it and checking the calibration on my workbench before I take it to the airport and try it on my engine:

There's a lot of talk about the value of angle-of-attack instruments in GA. I feel a little guilty since I don't even have a stall horn. Now that my airplane is built and less convenient to work on, I might never have one. I like to think that some sort of pressure-sensitive material could be attached to the leading edge of the wing and wirelessly transmit AOA data to a display in my cockpit. I've worked with low power RF transmitters and imagine a small coin cell battery or small solar panel would be all that is required for power.

 

[Del Herring]

hey, don't sweat telling me something I might know. I'm not even a pilot yet, so who knows what I've never even considered.

I think you're spot on with vibration analysis, and that's the direction I was starting to head myself. I did a little research today, and Lycoming did some reports indicating that bearing failure, connecting rod failure, and valve failures were the most common problems. Bearings could definitely be picked up using vibe analysis, long before they got noisy enough for a pilot to hear. And I suspect the same is true of connecting rod problems unless they're failing quickly due to something like severe detonation.

Valve problems could probably show up via tracking of exhaust gases, which wouldn't even require mounting anything to the engine itself, which would probably be nice for people in general aviation concerned with certified engines. I'm guessing mounting sensors to a certified engine might ruin the certification.

The wireless stall warning is an interesting idea. I'm always a little distrusting of wireless reliability, but something's better than nothing. I need to do some research into props too. I found the Nall report, which was a crash study the FAA did back when. It showed that, after pilot error (which was the biggest problem by far) engine and prop failures were the next leading cause. It didn't give a breakdown between engine and prop though. I suspect the same vibration analysis techniques could be useful for prop health, as being out of balance will produce vibes.

You guys are a huge help, thanks a lot for your input, we appreciate it.

 

[aeroaddict]

I might get blasted for saying this, but you need to 'show me the money'. Health monitoring for safety is a noble cause, but it needs to pay.

How it can pay in GA is part life limit extension. Using your example, what if you could reliably predict TBO on an engine? If you could demonstrate by analysis that an engine can go 3500 hrs between TBO instead of the 'recommended' (or required sometimes) 2000 hrs, you just saved me some money.

Cheers

 

[TFeeney]

Oil Health

What about oil condition monitoring? Wouldn't there be a case to be made for increased oil change intervals or improved fault detection through live monitoring? Looking at acid numbers, or metal content? Talk to the Savvy oil analysis guys...

 

[Del Herring]

You're not wrong, aeroaddict. If nothing else, I think detecting things like bearing wear before they become full failures would be a money saver, but yea, if capability to extend TBO or other maintenance can be extended, that would be great.

Oil condition monitoring could be interesting. It's certainly not a common cause of failure from the research I've done. But there may be some optimization to be done in terms of cost of oil vs cost of wear on the engine. I'm not sure what kind of hardware would be needed to monitor oil condition, I'll see if I can find someone knowledgeable in the area. If it takes 50 pounds of equipment I'm guessing it won't go over well. Might be as simple as an inline sensor somewhere though.