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#1
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Different plane, same fix
When we flew our '75 Warrior, it developed a problem with the
alternator going off-line in flight. This was preceeded by the ammeter needle bouncing crazily and finally pegging at 60 amps. I fixed that problem by spending an hour tracing all the electrical lines, and tightening connections. The main culprit was a wire connector that was screwed into the backside of the alternator with a simple phillips screw -- no safety wire, no loc-tite, no nuthin'. Looked like a ground wire to me, but I'm no mechanic. I turned it a good two and half turns, and the problem went away, never to return. We sold the plane in '02. Recently, Atlas developed a nasty, annoying whine in the headphones. This developed immediately after I had removed the PS Engineering CD/ Intercom for some panel maintenance, so I naturally assumed that they were related. No amount of re-seating, cleaning, wiggling had any effect. My frustration was mounting. Then, this past Sunday, I decided to chang the oil after our return flight from the Cherokee Pilots Association fly-in. It was Fathers Day, it was 100 degrees in the hangar, and we were both melting, but I decided to de-cowl the plane in order to make the oil change easier, and to trace the wiring -- just in case it was another loose connection somewhere. Of course, the first place I looked was the backside of the alternator, and, lo and behold, the same damned wire was loose! A few turns to tighten, and voila! -- no more whine. (I traced the rest of the wiring, while I was at it, and found a couple of broken zip ties, and one broken wire -- a lead going to one of my cylinder heaters. It's broken right where it goes into the cylinder -- THAT looks like absolutely no fun to repair...) Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... Thanks! -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination |
#2
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Different plane, same fix
"Jay Honeck" wrote in message oups.com... When we flew our '75 Warrior, it developed a problem with the alternator going off-line in flight. This was preceeded by the ammeter needle bouncing crazily and finally pegging at 60 amps. I fixed that problem by spending an hour tracing all the electrical lines, and tightening connections. The main culprit was a wire connector that was screwed into the backside of the alternator with a simple phillips screw -- no safety wire, no loc-tite, no nuthin'. Looked like a ground wire to me, but I'm no mechanic. I turned it a good two and half turns, and the problem went away, never to return. We sold the plane in '02. Recently, Atlas developed a nasty, annoying whine in the headphones. This developed immediately after I had removed the PS Engineering CD/ Intercom for some panel maintenance, so I naturally assumed that they were related. No amount of re-seating, cleaning, wiggling had any effect. My frustration was mounting. Then, this past Sunday, I decided to chang the oil after our return flight from the Cherokee Pilots Association fly-in. It was Fathers Day, it was 100 degrees in the hangar, and we were both melting, but I decided to de-cowl the plane in order to make the oil change easier, and to trace the wiring -- just in case it was another loose connection somewhere. Of course, the first place I looked was the backside of the alternator, and, lo and behold, the same damned wire was loose! A few turns to tighten, and voila! -- no more whine. (I traced the rest of the wiring, while I was at it, and found a couple of broken zip ties, and one broken wire -- a lead going to one of my cylinder heaters. It's broken right where it goes into the cylinder -- THAT looks like absolutely no fun to repair...) Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... Arc weld it. |
#3
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Different plane, same fix
On 06/20/07 08:54, Jay Honeck wrote:
[ snip ] Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... Thanks! Can you get a bolt/screw that will fit the threads and which can be safety wired? ... or would that not be an "approved" part? |
#4
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Different plane, same fix
Well if conductivity can be maintained, loctite (not red) should be
okay, used sparingly of course. Dare I say a blob of silicone over the whole thing? Something harde seems scarey to use, like JB Weld or liquid solder, epoxy glue and such. New lockwashers are probably in order. I am going to go check my alternators tomorrow.... John Jay Honeck wrote: When we flew our '75 Warrior, it developed a problem with the alternator going off-line in flight. This was preceeded by the ammeter needle bouncing crazily and finally pegging at 60 amps. I fixed that problem by spending an hour tracing all the electrical lines, and tightening connections. The main culprit was a wire connector that was screwed into the backside of the alternator with a simple phillips screw -- no safety wire, no loc-tite, no nuthin'. Looked like a ground wire to me, but I'm no mechanic. I turned it a good two and half turns, and the problem went away, never to return. We sold the plane in '02. Recently, Atlas developed a nasty, annoying whine in the headphones. This developed immediately after I had removed the PS Engineering CD/ Intercom for some panel maintenance, so I naturally assumed that they were related. No amount of re-seating, cleaning, wiggling had any effect. My frustration was mounting. Then, this past Sunday, I decided to chang the oil after our return flight from the Cherokee Pilots Association fly-in. It was Fathers Day, it was 100 degrees in the hangar, and we were both melting, but I decided to de-cowl the plane in order to make the oil change easier, and to trace the wiring -- just in case it was another loose connection somewhere. Of course, the first place I looked was the backside of the alternator, and, lo and behold, the same damned wire was loose! A few turns to tighten, and voila! -- no more whine. (I traced the rest of the wiring, while I was at it, and found a couple of broken zip ties, and one broken wire -- a lead going to one of my cylinder heaters. It's broken right where it goes into the cylinder -- THAT looks like absolutely no fun to repair...) Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... Thanks! -- Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination |
#5
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Different plane, same fix
Jay Honeck wrote:
Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... New phillips screw, new external tooth lockwasher, loctite (medium grade removable type), add it to the list of inspection items when the cowl is off the airplane. There may be a drilled head screw/bolt you could use, but you mentioned there is no way to safety wire it.....I assume that means nothing on the back of the alternator to wire it to. Steve |
#6
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Different plane, same fix
Jay Honeck wrote:
I fixed that problem by spending an hour tracing all the electrical lines, and tightening connections. The main culprit was a wire connector that was screwed into the backside of the alternator with a simple phillips screw -- no safety wire, no loc-tite, no nuthin'. Looked like a ground wire to me, but I'm no mechanic. SNIP Anyway, what should I put on this stupid screw to stop it from vibrating loose? LocTite? Another lock washer? There's no way to safety wire it... "Generally" there's only 2 wires on the alternator; the field wire from the regulator, and the output. Ground is usually established through the case of the alternator and associated bracket. If it was a relatively thin wire, it was more likely that it was the field. If that's the case, you defintely DON'T want to safety wire it. A fresh lock washer, and if you absolutely must, a very small dab of Locktite. There's always a chance that it was some sort of "extra" ground that someone added, but if that being loose is causing a whine, it seems like something else is also wrong (and the extra ground is covering it up). --- Jay -- Jay Masino "Home is where My critters are" http://www.JayMasino.com http://www.OceanCityAirport.com http://www.oc-Adolfos.com |
#7
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Different plane, same fix
PLEASE, NO LOCTITE. LOCTITE MEANS THAT YOU NEVER WANT TO REMOVE THE SCREW
AGAIN, which is going to play hell if the alternator itself ever craps out. If it is a bare wire, then no lockwasher in the world will help. Put a crimp terminal on the wire and then an INTERNAL TOOTH star or splitring lockwasher. The order of assembly is alternator, crimp terminal, lockwasher, screw. Jim -- "Dream as if you'll live forever. Live as if you'll die today." --James Dean "Jay Honeck" wrote in message oups.com... When we flew our '75 Warrior, it developed a problem with the alternator going off-line in flight. This was preceeded by the ammeter needle bouncing crazily and finally pegging at 60 amps. |
#8
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Different plane, same fix
Jay Honeck wrote:
When we flew our '75 Warrior, it developed a problem with the alternator going off-line in flight. This was preceeded by the ammeter needle bouncing crazily and finally pegging at 60 amps. [...] The main culprit was a wire connector that was screwed into the backside of the alternator with a simple phillips screw -- no safety wire, no loc-tite, no nuthin'. Looked like a ground wire to me, but I'm no mechanic. Disclaimer: This is based on experience with ground vehicles and by looking at the generator setup on a 182. I don't have an A&P; I don't even have a TG&Y. Some of this may not be allowable owner maintenance. Some of this may not be allowable on a certificated aircraft. Your mileage may vary. Sounds like the field wire to me. A loose ground wire would probably tend to make the ammeter read less (discharge), rather then pegging at max charge. There are some variations, but in general, a generator or alternator with external regulator will have three connections: - Main output wire. This carries all of the current coming out of the generator or alternator. Usually the fattest (thickest) wire on the device, and often bolted on to a fairly substantial stud - 0.25"/6.3 mm or more diameter. The stud will be insulated from the metal case of the machine. - Field wire. The regulator turns this on and off to control how much current the main wire puts out. This is a relatively thin wire (on the order of 14 gauge or 1.5 mm^2) and may be bolted to a stud or screwed to a metal terminal. The stud or screw will be relatively small, like #8 or #10 (maybe 3 or 4 mm). The stud or terminal will be insulated from the metal case of the machine. - Ground connection. Often done through the mounting bolts, but some may have a separate ground wire or strap. It will be at least as thick as the field wire and possibly as thick as the main output wire. It may also be a woven metal strap instead of a wire. This will be bolted directly to the metal casing of the machine with no insulation. Again, there are variations, but this is probably the most common setup on older aircraft. Of course, the first place I looked was the backside of the alternator, and, lo and behold, the same damned wire was loose! A few turns to tighten, and voila! -- no more whine [in radio audio]. Before you fiddle with this, make sure the master is off. For extra safety, disconnect the battery negative cable. Look at the place the screw goes into. Is there a plastic ring or boss around it, insulating the screw from the case of the machine? If so, then it's NOT a ground wire, and you CANNOT safety wire it to anything that is grounded. Also, look to see how contact is made. There should be a ring terminal on the end of the wire. If there is a fairly substantial ring of metal on the machine under the ring terminal, such that it contacts all of the ring terminal all around, then that's probably where most of the electrical contact happens, and the screw threads are just there to hold it down. (If not, see "A" below.) In this case, I would consider this: Get an aircraft-approved screw with the same thread as the existing screw, plus a hex (internal or external) head. Also get an aircraft-approved flat washer that fits the screw. You'll also need some brake cleaner or alcohol, the lowest grade of Loctite, something like a Q-tip, compressed air, and maybe some masking tape. Loctite comes in different grades and usually has a note like "can be disassembled with hand tools" or "must use power tools and/or heat to disassemble" on the package. You want the "hand tools" kind, which _will_ come apart when you want it to. Make su master off, battery disconnected. Unscrew the existing screw. Apply brake cleaner or alcohol to Q-tip and clean ring terminal on both sides; let it dry. Apply brake cleaner or alcohol to a fresh Q-tip and clean the screw threads; let it dry. If there is any possibility at all that you will get liquid into the generator/alternator, cover the holes with masking tape. Then put brake cleaner or alcohol on a fresh Q-tip and clean the place where the ring terminal bolts down - get down in the threads if at all possible. Let it dry for a few minutes, then give a gentle quick shot of compressed air in the threads to make sure it's dry. Assemble the washer onto the new screw (rounded edge away from screw head), then put the screw+washer through the ring terminal. Hold the screw+washer+terminal near the place it screws into, and apply the tiniest drop of Loctite that you can to the screw threads. (It may be helpful to put a drop of Loctite on a cleaned piece of solid wire, safety pin, etc, and then use that to put the Loctite on the threads, instead of trying to squeeze the Loctite directly onto the threads.) Start installing the screw, being very careful not to get any Loctite anywhere other than on the threads. If you get Loctite on the ring terminal or on the place where the ring terminal seats, take it apart, clean everything, and start over. Once the screw is finger tight, get the proper wrench or Allen key and torque it to spec. Remove any masking tape that was applied and reconnect the battery. Count your tools. Do a test run. A: On the other hand, if the underside of the ring terminal is not totally in contact with metal, then some of the electrical contact may be taking place on the threads and Loctite may not be advisable. The best answer in this case is probably to install an approved lockwasher under the screw head (it should go screw, lockwasher, ring terminal, machine), torque to spec, and inspect regularly. Disclaimer: This is based on experience with ground vehicles and by looking at the generator setup on a 182. I don't have an A&P; I don't even have a TG&Y. Some of this may not be allowable owner maintenance. Some of this may not be allowable on a certificated aircraft. Your mileage may vary. Matt Roberds |
#9
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TG&Y was Different plane, same fix
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#10
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TG&Y was Different plane, same fix
Gig 601XL Builder wrote:
I don't have an A&P; I don't even have a TG&Y. OK how many hear understand the TG&Y reference? For extra points what did it stand for? Wasn't TG&Y a discount store? I remember them from the 60s/70s. John Galban=====N4BQ (PA28-180) -- Message posted via http://www.aviationkb.com |
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