Swift Electrical System

From: "michelle dolin" <>
Subject: swift question
I know it sounds strange, but I'm having problems removing a voltage regulator from a Swift. The regulator is in the box on the right side firewall. The mounting studs for it don't come through the firewall at all. Are they behind the box? It doesn't look like they do.

Yep, that's familiar - the screw heads are on the back side of the box. Loosen the Phillips Head screws in the corners of the J box. Then, with the box loose on the firewall clamp a straight common screwdriver bit in a vice grip. Turn the 3/8" nuts on the voltage regulator off, holding the slotted screw heads on the back side of the J box. For reassembly, make a stud by running on a common plain nut before installing the regulator, that will make it easier next time. You may need to install a countersunk washer to make it work right. I sounds like your voltage voltage regulator lasted over 50 years! Unless someone reinstalled it exactly like the factory! -- Jim M

From: Steve Roth <>
I had some new radios and an audio panel installed. I am getting excessive alternator whine. My Swift has a Cessna 60-Amp alternator installed (via one-time approval). Anybody have any suggestions on the type of filtering I could use? Does Cessna have a standard alternator filter? Thanks, Steve N2397B

Yes, if you'll look at the Cessna wiring diagram for a 60 amp alternator system you'll see a 5-1629-1 noise filter. If you have one, replace it. Also all the wires in the Cessna installation are shielded. A good radio shop can probably recommend a bigger filter if you need it. -- Jim

From: George McClellan <>
I have a new problem. with the master off and a trickle charger on the system. I have lost two batteries in six months. Both brand new Gills G35's. I installed the trickle charger because the battery would lose charge if not used weekly. I tried a volt meter between the a+ line and the system master solenoid. It didn't show any current draw. ??? something is drawing the battery so flat it won't take a charge. This problem comes and goes. George

I had this same problem with my '34 Ford. I put a volt meter between the A+ and ground (positive ground on old Fords you know) It showed a slight draw, less than one volt, with everything off and no key in the ignition. At this point, I just started disconnecting things, and when I disconnected the radio, the meter went to zero. Somehow part of the radio wiring bypassed the ignition switch, which would be like a master switch in an aircraft. I would try what you did before, only put the meter between the ground terminal of the battery and the ground strap. Then, I would presume you'll see some voltage draw. Do you have a relocated battery? Perhaps the master solenoid is not wired in properly. -- Jim

In recent updates Monty and others have dealt with George McClellan's electrical drain that caused the battery to run down repeatedly. Here is the final info from George on those problems...

From: George McClellan <>
The electrical problem was a short in the Exide trickle charger system that had been installed. It took a short time to find this since the charging system was disconnected while I was looking for the problem. The battery is installed in the tail with access from behind the seat. Thanks for asking and for your help. George

Subject: Re: electrical question
From: Bill Doty <>
N80572 is set up with a Delco generator and regulator. I have a wire (second) running from the field terminal on the regulator to a resistance coil then thru a fuse holder (30 amp) and finally to the buss bar behind dash.. Has been a long time since I worked on a generator system and I don't know what this wire is for. Also had a fuse holder hooked to the buss bar with a brass stud protruding out of the fuse cap, would this be a method of checking battery volt without opening the cowl?? -- BILL DOTY

As far as I know, there is just one wire from "F" on the generator to "F" on the regulator. If the "F" circuit is grounded, the generator output is dependent on the rpm of the generator. In other words, the regulator is non-operative. For nonstandard wiring, your guess is as good as mine. To hook a voltmeter into the system, all you must do is run from any A+ hot wire thru the meter to ground. Since you don't know the purpose of these wires, I suggest you trashcan them and rewire per the book. -- Jim

From: Steve Roth <>
I have an Electronic International FP-5 Fuel Totalizer installed. It is powered off the main buss. When I activate the gear up or down, the FP-5 resets (like a power on). I first suspected that the radio noise created by brushes of the Bosch STC Gear motor was getting into the electronics. Now I believe the activation of the gear motor either (1) causes the buss voltage to dip momentarily below a value needed by the FP-5; or (2) causes the master relay (Cessna type) to drop out momentarily for the same reason. Before doing anything, wish to seek an opinion (that always creates activity here!). I suppose I could prove out my theory by temporarily wiring the FP-5L to the battery side of the master relay. Could my master relay be getting "weak" (not holding in with voltage excursion caused by current draw of gear motor?  Was the Swift standard with the Cessna type master relay or was the manual switch mounted in the firewall electronics box standard on all Swifts? My hangermate's Swift has the manual switch; I have the Cessna type relay. Regards, Steve Roth

There were two types of master switches in production, the manual type and the electrical relay. s/n 3597 had the relay. I was hoping a "real" electrical type would answer your question. Why not do a little experimenting? Measure your gear motors amperage draw with the airplane on jacks. You will need a ammeter with a shunt. It should draw about 40 amps on gear retraction, if it exceeds 50 amps, the motor may be at fault. A new master relay only costs about $15 so if its weak, replace it. -- Jim

Steve, why not try a tech assist from Electronics International. Ask them if a momentary drop in voltage supplied to their system will cause the totalizer to reset. I know of other folks who have used their tech assist, and they were glad to help. You might be surprised. Ed Lloyd <>

From: "Amzallag, Gerard (TX40)" <>
Subject: Fuel totalizer tricks.
(Editor's note: Received this re: Steve Roth's totalizer problems mentioned in last update.)
Hello Steve.
As pilots and aircraft owners we always find new gadgets to add on aircraft. With the availability of new electronic or solid state devices for general aviation this sort of problem will be on the increase. Solid state electronics are designed to withstand some deviation of their electrical input power. Sometimes the manufacturer will build-in some isolation features (or resets) in case these tolerances are exceeded. With this out of the way I can tell you without hesitation that you are encountering a SPIKE when the landing gear motor is energized. The landing gear switch make and break the current to the motors. What you need to do is to get a filter or capacitor to choke the spike. Much like a chock absorber does on a car's suspension. An avionics guy could recommend one based on the inrush current of the electric motor. I hope this helps. Thanks. Gerard R. Amzallag, Project Lead Engineer, Honeywell NAPO,

RADIO PROBLEMS??? (080300)
From: Paul Barger <>
Jim, My name is Paul barger I live outside of Boston and tend to leaf through your chat discussions. I have a 1946 Swift with a Lyc. IO-360 engine and have been chasing a radio problem for 2 months. Since my May annual, I have had an engine noise (bleed thru) into my vhf radio. At idle power the scratchy noise is nonexistent. At high power settings it is unbearable. I have chased every wire from the push to talk buttons on the sticks, to all grounds (alt,mags,airframe). I think it must be either a mag bleed thru or an alt bleed thru. I select L/R mag in-flight and it does no go away. The only thing the IA did on the annual was change the plugs. Is it possible new plugs could somehow bleed thru? We checked all the plug wires and found no problems. The plugs themselves all test good. The only other thing I can think of is the volume/squelch switch on my narco radio is worn. Its a turn for volume control/pull for squelch test. The pull function for whatever reason is worn and moves in and out easily. Any ideas before I self distruct?? I appreciate any thoughts you might have. Thanks, Paul Barger N3729K <>

From your description it may be RF noise, probably from the alternator. Aircraft Spruce and others have filters have noise filters in their catalogues. The price is around a hundred bucks and they do work. I don't think you have noise from the magnetos/spark plugs because that type of noise is usually described as "clicking" or "buzzing". They do have filters for the mags and resistor spark plugs, however. You probably have a fiberglas cowl. You might also try gluing a metallic mat to the inside of the cowl to keep the source of any noise away from the radio antennas. You might also consider moving the VHF antenna back, presuming it is on the panel in front of the windshield, just inches from the engine accessories. The thing that has me puzzled is you indicate the problem just started after the annual. Did the alternator suffer some damage at that time? Can you borrow a handheld and see if the problem persists? There is the possibility the squelch control is not doing its job, or the noise is being transmitted to the cockpit via a wire or metallic engine control. The "cigarette" spring in the plugs should have positive contact and the cavity can be filled with DC-4 silicone grease. I welcome any comment from "real" radio/electric experts! -- Jim

From: Paul Barger <>
Jim, I think you could call this noise "clicking". It appears to click slower at lower power settings and then continuous at high power. I think it's important to note that prior to swapping out the plugs, no filters were necessary and the radio was as clear as could be. No alternator damage has occurred and I don't think antenna location would be the culprit. Everything radio related has been in place trouble free for 8 years. Squelch is an option but it works fine at low power settings i.e. on the gnd selecting squelch on/off. Tell me more about the cigarette springs and greasing the cavities. I'm almost convinced the problem lies with the plugs, I just don't know how or why?? One last thing, this afternoon I'm going to test fly it again. I can isolate the alternator, select each mag, and turn off the intercom. I don't think any of these will isolate the problem. If that's the case, what else could cause the noise? Thanks again for all the help. -- Paul

If there is rust in the spark plug or anything which causes resistance or a gap from the cigarette spring to the spark plug you will get noise. Clean in the spark plug cavities with a rotary wire brush. Make sure the springs make good contact. (stretch them slightly if necessary) The silicone grease should not be necessary, but many use it with success. "All Weather" plugs all but eliminate the possibility of spark plug nose, but that requires new plugs and ignition harness.  Perhaps at the annual, the ignition harness was disturbed enough to allow ignition noise. A shielded harness requires continuous shielding to work. Is your harness cracked, old and tired? You might need a new harness. -- Jim

From: Paul Barger <>
Jim, When you mention in the cavity, do you mean the spark plug threads in the cylinder? The plugs are new 5hrs, the harnesses/plug wires are all inspected/tested and in good shape. Duane Golding mentioned at Oshkosh the same thing I think you were talking about. Plugs that may need to be re-seated. Why would that cause noise. Either way I'm after them little suckers tonight!! Thanks Jim, If any brilliant ideas pop up give me a shout, Paul

No, by cavity I mean the top of the plug where the cigarette goes. You might try removing the plugs and put some metallic anti-sieze on the threads. If your plugs were put in dry there may be resistance between the cylinder and spark plug. -- Jim

Subject: Re: RADIO PROBLEMS ??
After rereading our previous correspondence, it is obvious you have a spark plug problem. Did a spark plug get dropped before you installed it? You might have one or more defective spark plugs. First of all, I would remove the spark plugs. Visually inspect them and test them. A broken insulator won't necessarily be found this way, but you can try. If you find nothing, reinstall the plugs using anti seize compound on the threads. Run up the engine and check to see if the problem is still there. If it is, obtain a known good plug and install it in one location and run the engine. Repeat this process for all 8 plugs. If this doesn't find the problem, I hate to mention it, but get a whole new set of plugs and start over. -- Jim

WHO'D A THUNK IT... (080400)
From: Al Andersen <>
Subject: August #3 GTS Internet Update
Radio noise:
Although radio noise can come from nearly anywhere, one of the least thought of places is the Aircraft Battery. Acting as a large electrical sink, it effectively reduces alternator/generator noise below the threshhold level that the radio's own filtering devices work better. When the battery is old or not very strong, the "electrical sink "properties go away, and you have radio noise that your radios can't filter out. You would be amazed how many radios I've fixed with a new 35 amp battery. It also starts the engine better! AL

From: Paul Barger <>
Jim, I pulled and cleaned the plugs, cleaned the cig cavities and adjusted the springs, pulled the radio and cleaned the connections, checked the connections on the intercom and push to talk switches, removed the battery and cleaned the terminals. Then I put the sucker back together and the radio works perfect!!! NO MORE NOISE. Go figure? Thanks again for the help.

Subj: N3791K
From: Ed Clegg <>
It appears my regulator is acting up and after dressing the points it still is. The number on the reg is 1118736D. Nobody seems to be able to come up with it. Are the Generators on the O-300A 20amp output? You did quite a few annuals on this and thought you might remember. Also is there an Alt conversion(stc) for the O300A? Any help would be greatly appreciated. Thanks, Ed Clegg

I forget the part numbers but any Delco regulator will work. The 35A regulator, for example will just regulate to a higher amp output. Even a 12A regulator will work, but will not give much output. I forget if 91K has a 25 Amp generator or what, but the regulator for a 25A generator is a 1118384. I remember 91K had generator/regulator problems some years ago and we fixed that by installing an extra ground in the "J" box. Dressing the points in a regulator usually means they are "overhauled beyond repair". There are STCed alternators for the O-300, but Cessna used a Ford 60 Amp alternator from the early '60's on, both on the O-200's and the O-300's. They are a bolt on and lighter than anything bigger than a 25A generator. The latest O-300's had them as factory equipment. I have installed several using the Cessna 172 wiring diagram on a field approval. -- Jim

Subj: Re: generator
From: Ed Clegg <>
Hi Jim, I did get a reg from a friend and all seems to be running fine now, but still unable to find what the gen output is. The tag on the gen is unreadable and there is no ref to it's rating in any of the paper work. Any ideas on how to find out? Would you send me a 337 copy of the Cessna alternator installation. I think that's the way to go. Thanks for your support, Ed

The 12A and 20A generators are physically the same size. (pretty short) The 25A generator is a little longer. The 35A generator is about 10" long and weighs 16 lbs. A 12A generator is p/n 1101876, a 20A generator is p/n 1101890, a 25A generator is p/n 1101879 and a 35A generator is p/n 1101887. I like a 20A generator, small light and today's radios don't require a lot of power. A 60A alternator is nice, but at full charge it can take a horsepower or two to turn it. When a former owner of N3791K, Ray Vosika, was here in Lake Elmo some years ago the generator failed and we put on (I think!) a 25A generator. Of course, it may have been replaced since. Like I mentioned before, that airplane had a lot of generator problems before we installed an extra ground at the regulator. I got an alternator approved 25 years ago, before I kept a file of my 337's. I will look thru my old files and see if I can find a copy. I sent Charlie Nelson a copy years ago and they have passed it on to many Swifters. I think they might get 5 bucks or something for a copy. -- Jim

Subject: Alternator 337
I was looking thru my files for an STC and I found my old field approval 337 for an alternator on a C-125. A C-145 and O-300 would be done in the same manner. If anyone wants a copy of my 337 they should send me their address. (a stamped self addressed envelope would be nice too!)  --  Jim

Subj: Re: Alternator inst 337
From: Ed Clegg <>
Hi Jim, You mentioned an extra ground was placed on the gen system of 91K. Would that have been at the reg? It seemed to be ok after I replaced the old one (reg), but acting up again. The ammeter is hooked up as near as I can figure as a load meter so it only shows what's being used. Last Sunday returning from Ma it when full to what I think was appox 20amps. The meter has no numbers. Shutting the strobes and radios off had no affect leading me to believe the current limiter was controlling. What do you think?

We installed an extra ground at the regulator, but an extra ground or two at the engine never hurt anything! If you study the Swift wiring diagram, you will see that's the way the ammeter is from the factory. I like it that way, on runup you get a good check on the generator, when running the flaps you get a near full needle deflection. Do a run up when you get a chance and note the ammeter needle at approx. 1000 rpm should show a slight charge. Then, when the flaps are cycled it should show near a full charge. This presumes the battery is normal. -- Jim

From: Larry Owen <>
Subject: February #3 GTS Internet Update -Reply
Hi Dennis
Just a FYI (or a why didn't I think of that sooner story ) N78278 has a history lately of being a slow starter. One week it would be fine, the next , it would grind endlessly, popping but not wanting to start. Swapping the battery did not really change anything, Jump starting helped but was still stubborn at times. Mags check out. Plugs cleaned and swapped upper and lower. Harness is new. Alt good. I more or less put the problems down as "Not flying it enough" (true anyway). Yesterday was looking at the starter, not wanting to replace it, not knowing what else to do. Began removing the battery cables in preperation of pulling the starter... battery cables... battery cables!!! THE BATTERY CABLES !!! Took a good hard look at the cables that ran from the battery to ground, battery to starter solenoid, solenoid to the starter. All had to be 20 years old, all where much smaller than what I would want. As I removed them, noticed lots of "not bright" metal and grime/corrosion at and in the junctions. Spend a lot a time cleaning terminals. Took the cables down to the local parts store and found "generic" cables, heavier, better insulated. New nuts and washers, Invested less that $20 for three cables. Now N78287's starter turns over twice a fast, starts in 3-4 blades, not 8-10 or more. Makes a huge difference in my attitude about getting going. Hummmm, now I'm wondering what else on this bird is 20 years old, working but not working hard enough. I may have to start a $20 a week replacement program for that next "good enough" part I find. Maybe "Spring Cleaning" should be "Spring Replacement & Upgrade" Have a good one ! Larry Owen N78278

Subj: Battery & Starter Cables
From: (Denis M. Arbeau)
I have ordered some new battery/starter cables from Bogert Aviation. Here is what they said the content of their "kit" is...
Our kit has the battery neg to ground @ 22", battery pos to master sol. @ 21", master solenoid to starter solenoid @ 17", and starter frame to firewall ground @ 27".
On my Swift, I have the battery neg to ground, battery pos to master sol, and master solenoid to starter solenoid. What I DON'T have is this "starter frame to firewall ground". My question is, where on the "starter frame" do I attach this 27" cable and where on the "firewall" do I attach the other end?

The Swift does not have this cable as original equipment. On your O-300B there are 3 studs and 2 bolts for bolting the starter to the accessory case. I would install one end of the cable underneath one of the nuts on one of these, whichever is most convenient. The other end should be bolted to some heavy structure, perhaps where the battery ground stud is located in the firewall. Or the cable could go to a steel "tab" fabricated and installed underneath an engine mount nut, but don't install the soft cable end directly on the engine mount bolt. -- Jim

THE MYSTERY WIRES...  (010103)
Subj: wires?
From: Paul Smith <>
Well, here's my next problem. I am trying to hook up the wires to the wings. Coming out of the wing root is a bundle of three wires. They attached on a BUS to three wires heading out the wing. One is the power to the wingtip position light. The other two remain a mystery. They are not the wires to the gear micro-switches. They don't seem to have any power to them. On the left wing, one wire coming out of the wing root is labeled, "47L" The other has no label on it. The two goin out the wing are labeled, "54L," and "59L" On the right side, the one coming out of the wing root is labeled, "62R" The two going out the wing are labeled, "55R" and "50R". I have scoured the diagrams, and can find no reference to them. The FBO who has been helping me with this project is also stumped. Got any ideas? By the way the gear and flaps work fine, all microswitches and lights working well. Thanks, Paul Smith
(My Swift is about as stock as they come and they are labeled )

I have seen those 3 wires but there is only one that works for the position light! Use your VOM and figure it out. The wires on the Position Light Circuit drawing in the Operators Manual are different from what you mention but that makes no difference, just use the one that works! Strobes were unknown in 1946 maybe those other wires are spares. -- Jim

Subj: Brushes
From: Paul Smith <>
Do you know anyone that has an original ammeter? Mine is shot. By the way, regarding the wires to the wing, I was told by Harley Howell that these are probably wires put in at manufacture for both the stall warning and landing light options. -- Paul Smith

That same ammeter was used on lots of Piper and Cessna airplanes. They may be different colors. Do you have an aircraft salvage place nearby you can check? -- Jim

Subject: original Swift battery box stencil
A while back I had a note from someone restoring a Swift to absolute original who wondered if I knew the wording of the stencil on the battery box as they left the factory. I didn't at that time. We needed battery box for 60B and Mark Holliday scrounged one up from his parts hangar. The wording on the outboard side is:

WARNING (5/8" high letters, red)
Check battery water level (1/4" high letters, red) every 10 hours or 2 months
Do not fill above the baffle plate
Excessive fluid will cause damage

There may be more but it is unreadable. -- Jim

Subj: Wing tip strobes
From: Howard Thalacker <>
Hi, Jim Hope you had a good holiday season and you are off to a great New Year. I am finally getting around to the wingtip strobe plans of last summer. Could you refresh my memory on what unit to buy and the paperwork to be done to complete the project. N3263K. Thanks, Howard Thalacker

The strobes I usually use are the AeroFlash Model 152-0007. Your mechanic must submit a 337 to the FAA for field approval. I have a "pet" form 337 write-up which has been accepted by the FAA many times. I can send you a copy for your mechanic to use as a guide or I can make out the required 337 for a slight fee -- leaving the mechanic signature block open of course, do you have a local mechanic who can install the strobes and make out the 337 form? -- Jim

Subj: Question on Electrical System on Swifts
From: Jack Meyer <>
Sir, After finding my new battery fairly dead (would not turn the motor over but the landing light would work) a few times in a row, I did some reading on past problems with the Swift electrical system. I noted that at 1000 rpms I should see a positive full charge when running the Hyd system to operate the flaps. I do not see that, in fact I see no apparent charge at all. Does this indicate a problem with the voltage regulator or some other problem? I do see a charge above 1500 rpm during runup and in flight. I did put a VOM between the neg terminal on the battery and the fuselage which showed no current flow at all. Which should indicate a possible short somewhere in the system. Thanks for the help and advice in advance. Jack Meyer N2321B

Do you have a generator or alternator? Assuming you have a generator, disconnect the field lead at the regulator and operate something over 1000 rpm. If the generator shows "charge" the trouble is a ground either in the generator field or field wire. If the generator shows "no charge" the regulator is at fault. Make sure the regulator is properly grounded. I have seen Swifts with a history of "regulator trouble" that went thru one regulator after another but after installing an extra ground -- no more trouble. Local Swifter Ken Kneer had a problem last year with his generator system -- we trouble shot it for a month and changed both the generator and regulator due to inconsistent readings. The trouble was corrosion on a pin in the Cannon plug in the "J" box on the firewall. I would say the most likely culprit is worn generator brushes or a bad regulator. -- Jim