---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 04/23/18: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:03 AM - Re: Z-12 contactor failure (Robert L. Nuckolls, III) 2. 10:00 AM - Z12 contactor failure (CORRECTION) (Robert L. Nuckolls, III) 3. 07:14 PM - Re: Z-12 contactor failure (FLYaDIVE) 4. 10:06 PM - Re: Z-12 contactor failure (Bob Verwey) ________________________________ Message 1 _____________________________________ Time: 09:03:43 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Z-12 contactor failure Bob: Yup There are all sorts of 'possible' possibilities, all without proof, but it DOES WORK! Many of our aircraft are 40+ years old. The original lubricants in the switches have long disappeared. They are NOT sealed switches. What has worked for many years are now failing. Just look Brandon's post. And, when it comes to the Stall Warning micro switch - Replacement with NEW is $1200+ used, about $600 to $700. All this can be prevented with a can of WD-40! WD40 can be useful in the maintenance of electro-whizzies with moving parts . . . and indeed, it was not originally designed to be a lubricant so much as a (W)ater (D)isplacer and cleaner. As a side benefit, it does have some degree of lubricity . . . as do many substances . . . but its service life as a lubricant is far outpaced by other products designed for lubrication. https://goo.gl/sbPhXj WD40 was major maintenance feature for the MQM107 target we used to build at Beech. https://goo.gl/otFkbp The engine was a very short service life device with minimal moving parts and INTENDED to become totally immersed in seawater during an offshore recovery. The first refurbishment move for the aircraft was to remove the engine and submerge it in a barrel of WD40. When the aircraft was ready to receive the engine, they hauled it out with compressed air and bolted it back on the airframe. Not needed on sealed DPST Toggle Switches. AND they are NOT 40+ years old. Obviously, a truly sealed switch cannot benefit from spray on remedies . . . I can't see how applying a lubricant like WD40 can be advantageous to the contacts on the switch...surely there will be burning volatiles or lube which would affect the service or life of the part? On the moving parts yes but I don't know of a way to differentiate with a spray can. WD40 is often applied to moving part for the purpose of loosening corrosion and flushing out small particulates while displacing any moisture present. The combustible VOLATILES are just that . . .they quickly dissipate after carrying WD40 'magic juice' to the intended surfaces. If the Master Switch failed why reinvent the wheel? Since this was a certified plane you are forced to work with the design of the time. What I have found is 99.982% of certified plane owners and A&P's, NEVER address the Master Switch during Annual. It should be addressed every Annual and it is very easy to do: 1 - Spray the heck out of it with Contact Cleaner. 2 - Cycle the switch a couple of dozen times. 3 - Spray it with WD-40. My first job at Cessna extended over 5 years in the technical publications department where, among other things, I wrote repair and preventative maintenance narratives in Cessna's service manuals. Emacs! The policy of the company was to 'replace on condition' meaning that devices like relays and toggle switches were considered and sometimes tested to see that they met service life design goals. If a such a device were to mis-behave, it was time to replace it. Hence no maintenance or refurbishment methods were offered or required. Side Note: This also goes for the micro-switch in the Stall Warning System. The basic switch used on the legacy stall warning sensor was a Honeywell BZ series commercial off the shelf device with very low operating force (measured in grams). Of course, as a component in a PMA/TSO product, the owner operator was prohibited from replacing said switch for $20 (and I wasn't allowed to write a procedure for it either). These are not sealed switches and they're mounted in one of the more hostile environments on the airplane. Depending on the mis-behavior mode, an application of WD40 may well free up things and restore normal operation . . . but a switch that was not working normally was probably pretty long in the tooth. Depending on criticality of the device, it may well be better to replace as opposed to refurbish the individual switch. On Experimental Aircraft you have a HUGE ADVANTAGE... Use a Heavy Duty Master Switch and a Separate Heavy Duty Alternator Switch. I use DPST switches and tie BOTH sides together. This DOUBLES the physical as well as the electrical rating of the switch. Paralleling contacts only doubles the CARRY rating of a switch . . . it does not double opening or closing ratings. Want to go extra fancy? Look for switches that are Sliver Plated. Silver plating or solid silver contacts are rare and intended for specific applications . . . which generally do not include switching DC power. Cadmium Silver contacts are used in the more robust designs favored by mil-spec designs . . . but I suspect the Carling style products used on hundreds of thousands of TC aircraft are not so 'fancy' . . . yet demonstrably adequate to task. You can also use switches that have a built in Dust/Moisture shield. OR... Install the dust/Moisture shield over the Toggle Lever. Side Note: On certified planes with the standard split Master/Alt Switch, there are four (4) failure points: 1 - The Physical snap action of the switch. 2 - The Electrical contacts of the switch. 3 - Fast-On tabs on the back of the switch. 4 - The Physical MOUNTING of the switch. There is a snap in bezel that holds the switch into the panel. This bezel fails as the ears either break off or loose their spring action. Then the switch vibrates forward and shorts out to the aluminum panel. The cure is to use two (2) sheet metal round head screws on either side to hold the bezel in place. If the switch vibrates out it will short out and take your Master/Alt switch and Starter Relay out of the circuit. If you are airborne - You loose even the ability to go to Battery Back-up. Or do an in-flight re-start. Scary! Can you cite any service difficulty report that describes such a failure of the mounting? These switches are used by hundreds of thousands for about 50 years. I find it curious that anyone would find them (1) lacking in design to intended task and/or (2) figuring significantly on the list of probable failure that creates a hazard to flight. I know it is not a likely case, but I have experienced a contactor failure on a production plane in flight. It ended up that the root cause was a defective master switch - but the result was the same. Because there was no endurance bus alternate feed, it was a full electrical shutdown, in IMC no less! Then it wasn't a contactor failure but a switch failure. How did it manifest in flight? i.e. how did you become aware of the failure? Did things simply go black? I would like to know if there is a practical way to protect for contactor failure ( other than battery only operation ) with the Z-12 design. It would be nice to have a second path to the battery from aux alternator to ensure stable power if the master does fail. You can move the aux alternator wiring to the hot side of the battery contactor . . . it's just that simple. The appeal to me of having an aux alternator is to be able to continue flight on one alternator. This is only possible if either a battery connection is maintained always or it is a guarantee the alternator will provide stable power without a battery connection. Batteryless operation is likely but cannot be guaranteed without testing on your airplane with your constellation of hardware. As I've mentioned, there are Beechcraft piston aircraft wherein battery-off operation is described and permitted as a matter of design and verification by flight testing. It's covered in the POH. For this forum cannot make configuration/operation recommendations without conducting similar investigations as to meeting design goals The Z-13/8 uses a relay with the SD-8 alternator to connect directly to battery. Is this design practical or even advisable with the SD-20 alternator? With Z-13/8 the aux alternator will provide power to battery bus and E-BUS if contactor fails. Exactly. If you wish, you can certainly wire the SD20 in a manner suggested by Z13/8. There are no 'rules' that would prohibit you from doing so. When I took Z13/20 off the table about 10 years ago, it was because it added a degree of complexity over Z12 that did not materially reduce risk. In fight contactor failure is exceedingly rare. Smoke in the cockpit probably has a higher degree of probability . . . in which instance you may wish to shot the whole system down anyhow. Any of you who have attended my weekend seminars may remember this slide: Emacs! The last 200-300 hours of my flying days were carried out with these three items in my flight bag. Since I flew nothing but rentals, I had little insight as to the history of electrical/electronics systems. I was prepared to continue flight to intended destination with the master switch OFF. Indeed, the performance of these $100 hand-held gps receivers so exceeded the panel mounted stuff that those last hundreds of hours were flown with DUAL gps receivers 'mounted' to the glare-shield and windshield with little blobs of windshield sealant. Never touched a VOR receiver or even the panel mounted GPS receivers again. As I describe in Chapter 17 of the 'Connection, system reliability has far more to do with pilot skills and careful crafting of a Plan-B than it does on any selection of system hardware. The carefully crafted architecture and pilot's personal bag of tricks strives for failure tolerance . . . not failure proofing. The later cannot be achieved. Bob . . . ________________________________ Message 2 _____________________________________ Time: 10:00:11 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Z12 contactor failure (CORRECTION) In-fight contactor failure is exceedingly rare. Smoke in the cockpit probably has a higher degree of probability . . . in which instance you may wish to shot the whole system down anyhow. Any of you who have attended my weekend seminars may remember this slide: Emacs! The last 200-300 hours of my flying days were carried out with these three items in my flight bag. Since I flew nothing but rentals, I had little insight as to the history of electrical/electronics systems. I was prepared to continue flight to intended destination with the master switch OFF. Indeed, the performance of these $100 hand-held gps receivers so exceeded the panel mounted stuff that those last hundreds of hours were flown with DUAL gps receivers 'mounted' to the glare-shield and windshield with little blobs of windshield sealant. Never touched a VOR receiver or even the panel mounted GPS receivers again. As I describe in Chapter 17 of the 'Connection, system reliability has far more to do with pilot skills and careful crafting of a Plan-B than it does on any selection of system hardware. The carefully crafted architecture and pilot's personal bag of tricks strives for failure tolerance . . . not failure proofing. The later cannot be achieved. Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:14:38 PM PST US From: FLYaDIVE Subject: Re: AeroElectric-List: Z-12 contactor failure Bob: You are going off on tangents - - - On Mon, Apr 23, 2018 at 12:02 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > Bob: > > Yup There are all sorts of 'possible' possibilities, all without proof, > but it DOES WORK! > Many of our aircraft are 40+ years old. The original lubricants in the > switches have long disappeared. > They are NOT sealed switches. > What has worked for many years are now failing. Just look Brandon's post .. > And, when it comes to the Stall Warning micro switch - Replacement with > NEW is $1200+ used, about $600 to $700. > All this can be prevented with a can of WD-40! > > WD40 can be useful in the maintenance of electro-whizzies > with moving parts . . . and indeed, it was not originally > designed to be a lubricant so much as a (W)ater (D)isplacer > and cleaner. As a side benefit, it does have some degree of > lubricity . . . as do many substances . . . but its service > life as a lubricant is far outpaced by other products designed > for lubrication. > > =8BBarry - Nobody said it was being used as a lubricant, only you. It will work as a lubrcant to the contact areas of plastic switches and even the metal pivot points. How long will it last? I don't know... As I said in my post; A&P seldom address switches and many of these switches are 40 + years old. So, anything that one can do to extend their life or rejuvenate them is a good thing. Back to the WD... It is being used =8B =8Bas a WD and as a CLEANER! Oh wait... Can it be used as a cleaner??? DEFINITELY YES!=8B Do you have proof that it can't be? https://goo.gl/sbPhXj > > WD40 was major maintenance feature for the MQM107 target > we used to build at Beech. > =8BBarry - So!!! Who cares!=8B > > https://goo.gl/otFkbp > > The engine was a very short service life device with > minimal moving parts and INTENDED to become totally > immersed in seawater during an offshore recovery. > =8BBarry - Want more info on this subject? I did salvage and artifa ct recovery way-way back in the 70's and 80's . Who cares!=8B > > The first refurbishment move for the aircraft was to remove > the engine and submerge it in a barrel of WD40. When the > aircraft was ready to receive the engine, they hauled it out > with compressed air and bolted it back on the airframe. > > Not needed on sealed DPST Toggle Switches. AND they are NOT 40+ years ol d. > > Obviously, a truly sealed switch cannot benefit from > spray on remedies . . . > =8BBarry - That's why I said you CYCLE the Switches a couple dozen ti mes.=8B =8BWhy are you going off on so many tangents?=8B > > I can't see how applying a lubricant like WD40 can be advantageous to the > contacts on the switch...surely there will be burning volatiles or lube > which would affect the service or life of the part? On the moving parts y es > but I don't know of a way to differentiate with a spray can. > > WD40 is often applied to moving part for > the purpose of loosening corrosion and flushing > out small particulates while displacing any > moisture present. The combustible VOLATILES are > just that . . .they quickly dissipate after carrying > WD40 'magic juice' to the intended surfaces. > =8BBarry - You advertise yourself as an engineer. =8B =8BIf so, why are you so closed minded to other possibilities? =8B There are curtain things in physics that cannot be changed, but how a product can be used and to Great Advantages is sure out there. > > If the Master Switch failed why reinvent the wheel? > > Since this was a certified plane you are forced to work with the design o f > the time. > What I have found is 99.982% of certified plane owners and A&P's, NEVER > address the Master Switch during Annual. > > It should be addressed every Annual and it is very easy to do: > 1 - Spray the heck out of it with Contact Cleaner. > 2 - Cycle the switch a couple of dozen times. > 3 - Spray it with WD-40. > > My first job at Cessna extended over 5 years > in the technical publications department where, > among other things, I wrote repair and preventative > maintenance narratives in Cessna's service manuals. > =8BBarry - So what? Anybody can sit down behind a desk and write a ma nual. I have for a few dozen Environmental Test procedures. ANYTHING can be written. Ask the A&P and IA that is TRY to follow =8B =8Bwhat some paper-pusher =8Bwrote IF it is possible. Ask the plane owner who has to pay the bill why a simple thing like the Cessna Seat Rail Tracks has to be replace and WHY it is so expensive! =8B Or how to replace the Flap Motor on a Cessna.=8B > [image: Emacs!] > > The policy of the company was to 'replace on condition' > meaning that devices like relays and toggle switches > were considered and sometimes tested to see that > they met service life design goals. If a such a device > were to mis-behave, it was time to replace it. Hence > no maintenance or refurbishment methods were offered > or required. > > Side Note: This also goes for the micro-switch in the Stall Warning > System. > > The basic switch used on the legacy stall warning > sensor was a Honeywell BZ series commercial off > the shelf device with very low operating force > (measured in grams). Of course, as a component > in a PMA/TSO product, the owner operator was prohibited > from replacing said switch for $20 (and I wasn't > allowed to write a procedure for it either). > > These are not sealed switches and they're mounted > in one of the more hostile environments on the airplane. > Depending on the mis-behavior mode, an application > of WD40 may well free up things and restore normal > operation . . . but a switch that was not working > normally was probably pretty long in the tooth. Depending > on criticality of the device, it may well be better > to replace as opposed to refurbish the individual > switch. > > > On Experimental Aircraft you have a HUGE ADVANTAGE... > Use a Heavy Duty Master Switch and a Separate Heavy Duty Alternator Switc h. > I use DPST switches and tie BOTH sides together. This DOUBLES the > physical as well as the electrical rating of the switch. > > Paralleling contacts only doubles the CARRY > rating of a switch . . . it does not double > opening or closing ratings. > > Want to go extra fancy? Look for switches that are Sliver Plated. > > Silver plating or solid silver contacts are > rare and intended for specific applications . . . > which generally do not include switching > DC power. Cadmium Silver contacts are used in > the more robust designs favored by mil-spec > designs . . . but I suspect the Carling style > products used on hundreds of thousands of TC > aircraft are not so 'fancy' . . . yet demonstrably > adequate to task. > =8BBarry - YES - They Are! But, as the fellow whom had the failure w as talking and as I was saying: These switches have NOT been addressed during Annuals over MANY - MANY YEARS! =8B =8BThe Experimental Owner has Great Advantages over the Certified Own er by making small changes that GREATLY extend the life and as you are so vigorous to report on 'Reduction of Failure Points'. So, why shouldn't they look for the better switch. Silver Plated or CadSilver? GAUD! Which way did you part the gnat's hairs on that one? Walking into a electronics store, the Simple question: Do you have any Silver Plated Contact Switch? Will result in the SAME results! When I order Manure I don't care if it is horse or cow. Either one will work! > > You can also use switches that have a built in Dust/Moisture shield. > OR... Install the dust/Moisture shield over the Toggle Lever. > > Side Note: On certified planes with the standard split Master/Alt Switch , > there are four (4) failure points: > 1 - The Physical snap action of the switch. > 2 - The Electrical contacts of the switch. > 3 - Fast-On tabs on the back of the switch. > 4 - The Physical MOUNTING of the switch. There is a snap in bezel that > holds the switch into the panel. > This bezel fails as the ears either break off or loose their spring actio n. > Then the switch vibrates forward and shorts out to the aluminum panel. > The cure is to use two (2) sheet metal round head screws on either side > to hold the bezel in place. > If the switch vibrates out it will short out and take your Master/Alt > switch and Starter Relay out of the circuit. > If you are airborne - You loose even the ability to go to Battery Back-up .. > Or do an in-flight re-start. > Scary! > > Can you cite any service difficulty report > that describes such a failure of the mounting? > =8BBarry - You must LOVE AD's! I found the problem twice. I fixed the problem twice.=8B =8BYES! The switches have lasted for many years. Does that mean the y cannot fail? And, as I said: It was not the switch. It was the mounting bezel. Just because a FAA 8070-1 report not exist AND I do not know if one does or does not exist, does not mean the problem does not exist. =8BJust look at the design of the retaining bezel and even you should be able to see there is a potential failure point. ESPECIALLY! When the switch is removed in tracking down a wiring issue. There are more things in Heaven and Earth Horatio than even Bob has knowledge on. Barry These switches are used by hundreds of thousands > for about 50 years. I find it curious that > anyone would find them (1) lacking in design > to intended task and/or (2) figuring significantly > on the list of probable failure that creates > a hazard to flight. > ________________________________ Message 4 _____________________________________ Time: 10:06:52 PM PST US From: Bob Verwey Subject: Re: AeroElectric-List: Z-12 contactor failure Gee Wizz Barry, Many have taken on Bob N, and many have failed.... In all the 15 + years I have been a member of this forum, the thing that has impressed me most is the decorum of the participants....just sayin! Best... Bob Verwey 082 331 2727 On 24 April 2018 at 04:12, FLYaDIVE wrote: > Bob: > > You are going off on tangents - - - > > On Mon, Apr 23, 2018 at 12:02 PM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > >> Bob: >> >> Yup There are all sorts of 'possible' possibilities, all without proof, >> but it DOES WORK! >> Many of our aircraft are 40+ years old. The original lubricants in the >> switches have long disappeared. >> They are NOT sealed switches. >> What has worked for many years are now failing. Just look Brandon's pos t. >> And, when it comes to the Stall Warning micro switch - Replacement with >> NEW is $1200+ used, about $600 to $700. >> All this can be prevented with a can of WD-40! >> >> WD40 can be useful in the maintenance of electro-whizzies >> with moving parts . . . and indeed, it was not originally >> designed to be a lubricant so much as a (W)ater (D)isplacer >> and cleaner. As a side benefit, it does have some degree of >> lubricity . . . as do many substances . . . but its service >> life as a lubricant is far outpaced by other products designed >> for lubrication. >> >> =8BBarry - Nobody said it was being used as a lubricant, only you. It will > work as a lubrcant to the contact areas of plastic switches and even the > metal pivot points. How long will it last? I don't know... As I said in > my post; A&P seldom address switches and many of these switches are 40 + > years old. So, anything that one can do to extend their life or rejuvena te > them is a good thing. Back to the WD... It is being used =8B > > =8Bas a WD and as a CLEANER! > Oh wait... Can it be used as a cleaner??? > DEFINITELY YES!=8B > Do you have proof that it can't be? > > https://goo.gl/sbPhXj >> >> WD40 was major maintenance feature for the MQM107 target >> we used to build at Beech. >> > =8BBarry - So!!! Who cares!=8B > > >> >> https://goo.gl/otFkbp >> >> The engine was a very short service life device with >> minimal moving parts and INTENDED to become totally >> immersed in seawater during an offshore recovery. >> > =8BBarry - Want more info on this subject? I did salvage and arti fact > recovery way-way back in the 70's and 80's . > Who cares!=8B > > >> >> The first refurbishment move for the aircraft was to remove >> the engine and submerge it in a barrel of WD40. When the >> aircraft was ready to receive the engine, they hauled it out >> with compressed air and bolted it back on the airframe. >> >> Not needed on sealed DPST Toggle Switches. AND they are NOT 40+ years >> old. >> >> Obviously, a truly sealed switch cannot benefit from >> spray on remedies . . . >> > =8BBarry - That's why I said you CYCLE the Switches a couple dozen times.=8B > > =8BWhy are you going off on so many tangents?=8B > >> >> I can't see how applying a lubricant like WD40 can be advantageous to th e >> contacts on the switch...surely there will be burning volatiles or lube >> which would affect the service or life of the part? On the moving parts yes >> but I don't know of a way to differentiate with a spray can. >> >> WD40 is often applied to moving part for >> the purpose of loosening corrosion and flushing >> out small particulates while displacing any >> moisture present. The combustible VOLATILES are >> just that . . .they quickly dissipate after carrying >> WD40 'magic juice' to the intended surfaces. >> > =8BBarry - You advertise yourself as an engineer. =8B > > =8BIf so, why are you so closed minded to other possibilities? =8B > There are curtain things in physics that cannot be changed, but how a > product can be used and to Great Advantages is sure out there. > >> >> If the Master Switch failed why reinvent the wheel? >> >> Since this was a certified plane you are forced to work with the design >> of the time. >> What I have found is 99.982% of certified plane owners and A&P's, NEVER >> address the Master Switch during Annual. >> >> It should be addressed every Annual and it is very easy to do: >> 1 - Spray the heck out of it with Contact Cleaner. >> 2 - Cycle the switch a couple of dozen times. >> 3 - Spray it with WD-40. >> >> My first job at Cessna extended over 5 years >> in the technical publications department where, >> among other things, I wrote repair and preventative >> maintenance narratives in Cessna's service manuals. >> > =8BBarry - So what? Anybody can sit down behind a desk and write a manual. > I have for a few dozen Environmental Test procedures. ANYTHING can be > written. > Ask the A&P and IA that is TRY to follow =8B > > =8Bwhat some paper-pusher =8Bwrote IF it is possible. > Ask the plane owner who has to pay the bill why a simple thing like the > Cessna Seat Rail Tracks has to be replace and WHY it is so expensive! > =8B Or how to replace the Flap Motor on a Cessna.=8B > > >> [image: Emacs!] >> >> The policy of the company was to 'replace on condition' >> meaning that devices like relays and toggle switches >> were considered and sometimes tested to see that >> they met service life design goals. If a such a device >> were to mis-behave, it was time to replace it. Hence >> no maintenance or refurbishment methods were offered >> or required. >> >> Side Note: This also goes for the micro-switch in the Stall Warning >> System. >> >> The basic switch used on the legacy stall warning >> sensor was a Honeywell BZ series commercial off >> the shelf device with very low operating force >> (measured in grams). Of course, as a component >> in a PMA/TSO product, the owner operator was prohibited >> from replacing said switch for $20 (and I wasn't >> allowed to write a procedure for it either). >> >> These are not sealed switches and they're mounted >> in one of the more hostile environments on the airplane. >> Depending on the mis-behavior mode, an application >> of WD40 may well free up things and restore normal >> operation . . . but a switch that was not working >> normally was probably pretty long in the tooth. Depending >> on criticality of the device, it may well be better >> to replace as opposed to refurbish the individual >> switch. >> >> >> On Experimental Aircraft you have a HUGE ADVANTAGE... >> Use a Heavy Duty Master Switch and a Separate Heavy Duty Alternator >> Switch. >> I use DPST switches and tie BOTH sides together. This DOUBLES the >> physical as well as the electrical rating of the switch. >> >> Paralleling contacts only doubles the CARRY >> rating of a switch . . . it does not double >> opening or closing ratings. >> >> Want to go extra fancy? Look for switches that are Sliver Plated. >> >> Silver plating or solid silver contacts are >> rare and intended for specific applications . . . >> which generally do not include switching >> DC power. Cadmium Silver contacts are used in >> the more robust designs favored by mil-spec >> designs . . . but I suspect the Carling style >> products used on hundreds of thousands of TC >> aircraft are not so 'fancy' . . . yet demonstrably >> adequate to task. >> > =8BBarry - YES - They Are! But, as the fellow whom had the failure was > talking and as I was saying: > These switches have NOT been addressed during Annuals over MANY - MANY > YEARS! =8B > > =8BThe Experimental Owner has Great Advantages over the Certified O wner by > making small changes that GREATLY extend the life and as you are so > vigorous to report on 'Reduction of Failure Points'. So, why shouldn't th ey > look for the better switch. > Silver Plated or CadSilver? > GAUD! Which way did you part the gnat's hairs on that one? > Walking into a electronics store, the Simple question: Do you have any > Silver Plated Contact Switch? Will result in the SAME results! When I > order Manure I don't care if it is horse or cow. Either one will work! > > >> >> You can also use switches that have a built in Dust/Moisture shield. >> OR... Install the dust/Moisture shield over the Toggle Lever. >> >> Side Note: On certified planes with the standard split Master/Alt >> Switch, there are four (4) failure points: >> 1 - The Physical snap action of the switch. >> 2 - The Electrical contacts of the switch. >> 3 - Fast-On tabs on the back of the switch. >> 4 - The Physical MOUNTING of the switch. There is a snap in bezel that >> holds the switch into the panel. >> This bezel fails as the ears either break off or loose their spring >> action. >> Then the switch vibrates forward and shorts out to the aluminum panel. >> The cure is to use two (2) sheet metal round head screws on either side >> to hold the bezel in place. >> If the switch vibrates out it will short out and take your Master/Alt >> switch and Starter Relay out of the circuit. >> If you are airborne - You loose even the ability to go to Battery Back-u p. >> Or do an in-flight re-start. >> Scary! >> >> Can you cite any service difficulty report >> that describes such a failure of the mounting? >> > =8BBarry - You must LOVE AD's! > I found the problem twice. I fixed the problem twice.=8B > > =8BYES! The switches have lasted for many years. Does that mean t hey > cannot fail? And, as I said: It was not the switch. It was the mounting > bezel. > > Just because a FAA 8070-1 report not exist AND I do not know if one does > or does not exist, does not mean the problem does not exist. > =8BJust look at the design of the retaining bezel and even you shou ld be > able to see there is a potential failure point. > ESPECIALLY! When the switch is removed in tracking down a wiring issue. > > There are more things in Heaven and Earth Horatio than even Bob has > knowledge on. > > Barry > > These switches are used by hundreds of thousands >> for about 50 years. I find it curious that >> anyone would find them (1) lacking in design >> to intended task and/or (2) figuring significantly >> on the list of probable failure that creates >> a hazard to flight. >> > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.