Maintenance and Pilots on the ball.
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Maintenance and Pilots on the ball.
THIS IS NOT A LAME BASH THREAD - DO NOT EVEN THINK ABOUT IT 
HOW MANY AIRCRAFT OWNERS TAKE AN ACTIVE INTEREST IN THE TECHNICAL RESULTS OF MAINTENANCE ON THEIR PLANE?
I thought I would start this thread to raise awareness of what you the pilot can do to better look after your aircraft and ensure it is configured in an optimal state.
Topics should be typically engine related although airframe and avionics can be discussed, so I will suggest things like plugs, magneto's fuel flow etc.
To kick off, lets look at a very smart guy, who randomly visits this forum and has a large pressurised twin. Turbocharged engines. This aircraft is maintained by a very good shop and has recently come out of annual. The plane does typically 12-13 hours a month or more. The aircraft is fitted with a good EMS setup and the pilot has been educated very well on understanding exactly what the EMS is telling him. No dog watching TV here!
Engine A is showing signs of lower TIT and higher CHT's and can not flow the typical LOP fuel flows without busting 380-385dF and has to be run around 20-30dF further LOP.
Engine B is not showing these symptoms, rather it seems not to be as smooth when LOP. The GAMI spread is still perfect however. The TIT is a bit higher and during an inflight mag check there is a bit more variation in the EGT bars.
What was found? Engine A had both mags timed with 1 degree too much advance, plugs were all fine. Engine B had several plugs with a gap beyond 0.018" and the mags were 2-2.4 degrees retarded. It should be noted this engine was also easier to start, and that makes sense too, the pilot noted this.
How many pilots out there would be this sharp? My guess is 1% at best.
This was not long out of an annual so the obvious question is how on earth is this possible? the answer is simple. Most LAME's do the best they can with the little they have. Many are still using the old timing gear marks under the brass plug or the hole/flywheel method. We used a Rite System kit.
Why is this important? Well on a TC engine 1 degree of timing really does make a big difference. With the digital Rite System you can pick and adjust in 0.1 degree increments, and a full degree is hard to pick using the old factory markings. So if the LAME is a bit slack or in a hurry or whatever, he can say "it's within tolerance" and think it is fine. But add another degree or two and it is not fine and may be very bad.
If you or your LAME do not have one, buy one and gift it to him/her.
Plugs.....If they are fine wires and tempest, not much to do, if Champion check their resistance. If they are massive electrode buy your self some gapping tools and every 50 hours clean and gap them. 0.016" to 0.018" is the range, set them at the lower end and recap at 50 hours. When they get to 20-22 thou they are not performing right.
I am sure there are plenty of stories that can be shared, so feel free to share or ask questions if you wish. I will do my best to answer them, or others here will for sure. There are some LAME's here that might have to help me out too.
Remember this is not a LAME slag fest. I will ask Taily to keep an eye on that. I want this thread to be all about learning and positive things.
I am out bush for the weekend so I may not be back to this till Monday, so play nice y'all.
HOW MANY AIRCRAFT OWNERS TAKE AN ACTIVE INTEREST IN THE TECHNICAL RESULTS OF MAINTENANCE ON THEIR PLANE?
I thought I would start this thread to raise awareness of what you the pilot can do to better look after your aircraft and ensure it is configured in an optimal state.
Topics should be typically engine related although airframe and avionics can be discussed, so I will suggest things like plugs, magneto's fuel flow etc.
To kick off, lets look at a very smart guy, who randomly visits this forum and has a large pressurised twin. Turbocharged engines. This aircraft is maintained by a very good shop and has recently come out of annual. The plane does typically 12-13 hours a month or more. The aircraft is fitted with a good EMS setup and the pilot has been educated very well on understanding exactly what the EMS is telling him. No dog watching TV here!
Engine A is showing signs of lower TIT and higher CHT's and can not flow the typical LOP fuel flows without busting 380-385dF and has to be run around 20-30dF further LOP.
Engine B is not showing these symptoms, rather it seems not to be as smooth when LOP. The GAMI spread is still perfect however. The TIT is a bit higher and during an inflight mag check there is a bit more variation in the EGT bars.
What was found? Engine A had both mags timed with 1 degree too much advance, plugs were all fine. Engine B had several plugs with a gap beyond 0.018" and the mags were 2-2.4 degrees retarded. It should be noted this engine was also easier to start, and that makes sense too, the pilot noted this.
How many pilots out there would be this sharp? My guess is 1% at best.
This was not long out of an annual so the obvious question is how on earth is this possible? the answer is simple. Most LAME's do the best they can with the little they have. Many are still using the old timing gear marks under the brass plug or the hole/flywheel method. We used a Rite System kit.
Why is this important? Well on a TC engine 1 degree of timing really does make a big difference. With the digital Rite System you can pick and adjust in 0.1 degree increments, and a full degree is hard to pick using the old factory markings. So if the LAME is a bit slack or in a hurry or whatever, he can say "it's within tolerance" and think it is fine. But add another degree or two and it is not fine and may be very bad.
If you or your LAME do not have one, buy one and gift it to him/her.
Plugs.....If they are fine wires and tempest, not much to do, if Champion check their resistance. If they are massive electrode buy your self some gapping tools and every 50 hours clean and gap them. 0.016" to 0.018" is the range, set them at the lower end and recap at 50 hours. When they get to 20-22 thou they are not performing right.
I am sure there are plenty of stories that can be shared, so feel free to share or ask questions if you wish. I will do my best to answer them, or others here will for sure. There are some LAME's here that might have to help me out too.
Remember this is not a LAME slag fest. I will ask Taily to keep an eye on that. I want this thread to be all about learning and positive things.
I am out bush for the weekend so I may not be back to this till Monday, so play nice y'all.
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Given that the aircraft owner is now the authorising person for the maintenance perhaps it is time that aircraft owners took a very keen interest in their aircraft and not just their wallet.
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Rather than gap massive every 50 hrs, I would recommend replace with Champion fine wire plugs. Massive only last 3-400 hrs before they would fail wear limits and they seem to have about doubled in price in a few years.(more than exchange rate change anyway)
That indicator behind the brass plug is not allowed to be used for timing any more due mandatory bulletin.
Been a few contact points funny wear in recent years on both Bendix and Slick recently, this normally a few hours after 500 hr inspection or O/H.
Cleaning inside where HT lead goes is often missed and can make a big difference in resistance.
That indicator behind the brass plug is not allowed to be used for timing any more due mandatory bulletin.
Been a few contact points funny wear in recent years on both Bendix and Slick recently, this normally a few hours after 500 hr inspection or O/H.
Cleaning inside where HT lead goes is often missed and can make a big difference in resistance.
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I prefer the saying why are we still flying piston engines.
Mostly cost, the STC mags are about 10% extra of a overhaul cost around 5K (at end of day).
Also about zero support in maintenance and parts.
The new Connies with extended TBO don't come with STC mags as option and the extra hours are better bang for buck than STC mags.
In Oz as soon as one of these companies goes broke product support is gone - so then is your use of them in OZ. But other reasons also, like mags actually do work fine very often.
Mostly cost, the STC mags are about 10% extra of a overhaul cost around 5K (at end of day).
Also about zero support in maintenance and parts.
The new Connies with extended TBO don't come with STC mags as option and the extra hours are better bang for buck than STC mags.
In Oz as soon as one of these companies goes broke product support is gone - so then is your use of them in OZ. But other reasons also, like mags actually do work fine very often.
Last edited by Band a Lot; 17th Aug 2016 at 07:35. Reason: clear up
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Would the commonly available apps available for iPhone do for digital protractor? Seriously
wouldve thought technology is the same or better than the time rite stuff
I feel this thread should provide fertile ground for observations of the Waddington Effect
wouldve thought technology is the same or better than the time rite stuff
I feel this thread should provide fertile ground for observations of the Waddington Effect
CASA does not understand the Waddington effect, hence overhauls of perfectly good propellers at an arbitrary interval without any supporting evidence and of course replacement of control cables, etc.
I ran head on into the Waddington effect about 1978 - F27 AP gyros.
I ran head on into the Waddington effect about 1978 - F27 AP gyros.
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Lumps, I would expect they would but you still need the in plug hole tool and a buzz box, and the cone/holder that fits the spinner......might as well buy one :-)
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Thanks for the reference to Waddington effect Lumps. I hadn't heard of it but it makes interesting reading. It sort of reflects my own experience that the time one had to be most careful of an aircraft failing you was when it was just out of maintenance.
If it was perfectly good, there would be no need for an overhaul. Presumably someone in this world, somewhere, has had a failure of this model of propellor and therefore they have taken action so as to protect users of that product.
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Squawk I think this a more accurate statement as CASA have used a blanket approach.
Presumably someone in this world, somewhere, has had a failure of a propeller!
Presumably someone in this world, somewhere, has had a failure of a propeller!