What happened to quality control in aviation???

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We're just finishing the first 100-hour inspection on our new aircraft that has a Lycoming TIO-540. The airframe sailed through the inspection with only a couple minor issues that shouldn't present future problems. The engine is a different story. The mechanic discovered that the timing was off between 4-5 degrees (advanced) on the left mag, which led him to check the internals of the mag for wear. . .upon opening the mag, he discovered it FULL of oil. The timing for the right mag was spot on spec but he opened it and discovered that it too was full of oil. Lycoming warranteed two new mags for us without question.

This aircraft has 93 hours TT. . .my concerns:

--That we've been flying this turbocharged engine with the advanced timing on the left mag causing detonation. How has this affected engine longevity? What damage, if any, has been done?

--How did this engine leave the factory with the mag timing so far off?

--What are the odds that BOTH mags would seep oil? Bad batch of seals? Poor quality control at Champion (Slick)?

I'll be talking to a Lycoming tech rep today about these issues. . .should be interesting. . . I'm quite dismayed about this.
 
Now that there's a glut of No Name Chinese parts on the market the situation can only get worse .
We used to be able to but quality materials at our local hardware stores ... now even the nails are trash !
 
I'm not so sure that 5 additional degrees on just one mag will cause detonation. You may know that Lycoming angle valve engines have settings at 20 degrees advance, and some have 25 degrees. There is no mechanical difference between the engines.

What operators discovered is that the additional timing creates more HP. However, there is a very narrow range of operation where detonation can occur on 25 degrees. Generally in very cold climates, full power, with full sea level manifold pressure and extremely cold intake air temperatures, AND the pilot leaning the mixture. AND the fuel being used at the lower end of the octane specification.

Hence the switch to 20 degrees.

Did your engine experience extreme CHT's? Especially on just one cylinder? That's the first indication of detonation. Or did you discover piston damage? If not, my guess is that you have not experienced detonation.
 
Magneto quality has always been suspect. It's a mechanical device.

Think about the way points operate. When the points close, current flows and the ignition coil is "charged". When the points open, the circuit is broken, the coil discharges and fires the spark plug.

Now, what happens when the point-cam and follower wear? The points open later, retarding timing. But, what happens when the point contacts wear? The points open earlier, advancing timing. Could your oil leak cause point contact wear?

Another thought, magneto ign timing is not all that accurate. When viewed with an accurate timing light, the timing dances a good bit. If viewed via computer, with each sparkplug measured, the inaccuracies are stunning. Especially at high power levels.
 
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Quote:
What happened to quality control in aviation???


Must have flown out the window....


sorry I couldn't help myself
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:p
 
Originally Posted By: bruno
Now that there's a glut of No Name Chinese parts on the market the situation can only get worse .


You mean like Continental engines? (now Chinese-owned).

frown.gif
 
Most of us dont like it but can deal with poor quality car parts but for an airplane thats a whole different story! You cant just pull over and check when a problem occurs!
 
Cujet. . thanks for the reply. Although I've been in aviation for 35+ years, my experience lies mostly on the piloting side. . . not so much on the maintenance side, although I've picked a lot up over the years. Your comments are somewhat comforting, although my mechanic considers it a big deal (considering the turbocharging). I'm new to this particular engine, although I have a few hours in Navajos, so I'm still getting up to speed on it's nuances.

Regarding the temps, we have a JPI EDM-800 engine monitor, which I religiously use to operate the engine--the EGTs and CHTs have always been pretty much even across the board and I lean the TIT within spec (52C rich of peak at cruise). I've never observed a spike in any of the cylinder temps. I'll be downloading the operational data from the EDM next week and will look for spikes.

I'm still waiting for a callback from Lycoming. . . thanks for commenting.
 
Will we ever see electronic ignition replace magnetos? Much better timing control, less maintenance, hotter spark and reliability that's just as good or better. The problem of needing to be powered by the aircraft's electrical system is a thing of the past with E- mag replacements now having internal brushless alternators.
 
I agree. . .the time has come for electronic ignition. It's proven itself in the automotive industry for decades. With today's technology it could be done, but I'm sure that the cost of certification is what's stymieing any movement in that direction. Meanwhile we have 21st century airframes using 100-year old engine technology. . .
 
Originally Posted By: ms21043
Will we ever see electronic ignition replace magnetos? Much better timing control, less maintenance, hotter spark and reliability that's just as good or better. The problem of needing to be powered by the aircraft's electrical system is a thing of the past with E- mag replacements now having internal brushless alternators.



Having used both the "lightspeed" elec ign and E-mag's P-model (the one with the generator) on an experimental velocity Lyc IO360 angle valve, I can say, without any doubt, electronic ignition results in smoother operation and very slightly lower fuel consumption. All good things. However, after the 4th lightspeed failure, it was switched to a P-mag, which failed only once so far.

HOWEVER..... Neither electronic ign resulted in HP gain, or faster top speed. In fact, there was some slight, but verifiable peak power and top speed loss. This is, in fact, normal for electronic ignitions.

Don't believe me? Here is some light reading for you. It verifies exactly what I am saying. There is quite a bit to this story.

http://cafefoundation.org/v2/research_reports.php



1) magneto's produce a very robust spark. There is a reason dragsters still use magneto's. In fact, they are far more powerful than electronic ign's.

2) The timing of a magneto is very close to ideal under certain circumstances. Such as full power operation.

3) The timing of a magneto is also close to ideal on turbo normalized aircraft, where high manifold pressure is a normal operating condition. In other words, there is no need to advance the timing under high load conditions.

4) Remember the dual spark plugs on OPPOSITE sides of the cylinder head? This configuration reduces the need for ign advance. Thereby allowing high power output (high BMEP) without excessive (and dangerous) ign advance. Don't compare automotive single plug operation and small, high speed cylinders, to large, slow moving, dual opposed spark plug design.

Please understand I'm not saying I like mags. I don't. But in many cases, they are not as awful as the electronic ign industry would like you to believe. A good example is the velocity I mentioned above, a 4 place aircraft with a small engine. The engine must work hard all the time. The electronic never gets a chance to advance the timing in CRUISE FLIGHT, and therefore the operator never sees the predicted fuel economy gains.

Let's look at it this way, in many lower powered aircraft, the pilot will fly full throttle, max power mixture, and the constant flow fuel injection system will flow exactly the same as before. And the electronic won't advance timing due to high manifold pressure. No gain.
 
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When considering a move toward electronic ignition, the only "gain" I'd be hopeful for would be dependability. I understand that electronic ignitions may fail, but I know for a fact that magnetos WILL fail. . . it's just a question of when, and it seems that nowadays the quality of certain aviation parts has declined noticeably, particularly Slick mags. In the last aircraft we had, we got bad mags out of the box TWICE). . .there's no excuse for that IMHO.
 
Call Japan , find out what they used in their Zeros,,I think they did just fine in December, 7th,,1941..............
 
Originally Posted By: Cujet


Please understand I'm not saying I like mags. I don't. But in many cases, they are not as awful as the electronic ign industry would like you to believe.


Years ago I used to work on Navajo Chieftains, this is what I remember about them:

The magneto for each engine was one unit that housed 2 mags and I was the guy who always got the mags on the 100 hour... Pull the mags off both engines, tear them down, clean them up, inspect, replace whatever needed, lube, re-assemble each correctly for engine rotation (#2 engine rotates CCW), adjust 3 sets of points in each mag, check/adjust internal timing normal and retard, re-install mags on correct engine and time them to the engine.. These mags have one drive, lose the drive and you lose the engine. I have seen a dead mag a few times on these airplanes, but never saw an engine quit, the remaining mag always worked. But yeah, after doing those mags all the time, I always thought there should be something better.

If nothing else, getting rid of points and triggering a mag electronically would be a step in the right direction.

On the Dragster mag, I read somewhere that the ones they use on a top fueler are putting out around 50k volts and 1.2 amps.
shocked.gif
These mags are electronically triggered.
 
I'm not exactly an expert in this area, but from what I think I know, the advanced timing may have caused detonation.

You may or may not have noticed a reduction in power output in high power settings like takeoff and climbout. If you think it's a distinct possibility, have the engine inspected more thoroughly.

As for the oil leaking into the mags...Sheesh. All I can say is probably bad oil seals.

If the mags are pressurized from the turbocharger, check the pressure lines for oil as a possible source of oil into the mag. My thoughts on this is possibly a bad oil seal in the turbocharger bearings, causing oil to leak into the compressor. (Less likely unless you notice it's burning a [censored] of a lot of oil.)
 
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UPDATE: Spoke to a Lycoming tech-rep who told me (surprise) that the advance timing on one mag isn't likely to cause any damage or longevity issues and that Lycoming and Slick are working on a known issue whereby the timing on their (Slick's) mags are drifting out of spec (advance) without evidence of internal wear. He also stated that Lycoming designs a lot of tolerance for timing variation into their engines and that 4-5 degrees wouldn't matter in the long term. He advised 100-hour checks of the timing on these mags, which we do anyway. Regarding the oil in the mag, he suspected bad seals and did mention oil ingress through the pressurization system for the mags, but seemed to favor the bad seal theory.

As for the engine itself, I've got about 15 hours on it since inspection and everything is running great. The JPI is showing temps even across the board and seems to be making normal power as before the mag change. I don't note any difference in operation since the mag change / timing change. Time will tell. . . .
 
UPDATE: At 114 hours TT, starter failed (Sky-Tec) at remote airport location. . . failure caused by a post (terminal) that was loose (could wiggle the post around). New one overnighted--two days flying lost. . . . labor paid to mechanic, and aircraft rental to location = expensive repair.

Shouldn't we expect more from OEMs than over-priced, poorly-made sub-components? This is getting stupid. . . . Lycoming should raise the bar for their vendors. . . .
 
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