---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 08/21/16: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:56 AM - Re: Voltage drop (Robert L. Nuckolls, III) 2. 07:04 AM - Re: Voltage drop (Robert L. Nuckolls, III) 3. 08:49 AM - Re: Voltage drop (Robert L. Nuckolls, III) 4. 09:19 AM - Re: Voltage drop (ashleysc@broadstripe.net) 5. 12:09 PM - Re: Voltage drop (Robert L. Nuckolls, III) 6. 01:08 PM - EFIS Power Switch (Art Zemon) 7. 01:27 PM - Re: Voltage drop (Chuck Birdsall) 8. 05:13 PM - Re: Voltage drop (Robert L. Nuckolls, III) 9. 06:19 PM - Re: Voltage drop (Jim Baker) 10. 07:16 PM - Re: Voltage drop (ashleysc@broadstripe.net) 11. 07:29 PM - Re: EFIS Power Switch (user9253) ________________________________ Message 1 _____________________________________ Time: 06:56:13 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltage drop At 08:57 PM 8/20/2016, you wrote: >Thanks Bob, > >I do have a backup battery that is already wired >in but have it disconnected because there is no charging going on. Don't understand this . . . is this a system battery that is part of your airplane's architecture or is it associated with a specific appliance as part of its design? >=C2 The other problem is that my odyssey battery >(680) was more discharged than I thought .=C2 It >is on a charger now and it should rectify the >problem. I was just concerned I had a bad relay >or miss-wired something.=C2 The good news is I >checked all my wiring Battery/ Alt. switch etc.=C2 They were all fine. . . . good connecting of the dots . . . >I do have a basic question that I cannot seem to >answer in my mind.=C2 When the Battery switch is >on, there is power going to the alternator via >the main B lead. Since that lead is connected >directly to the output side of the battery relay >dose it not draw a significant amount of current >when the Battery master is on and the alternator >is not running.=C2 In you book it show hat=C2 lead >connected to coils that are stationary in the >alternator, then to ground believe.=C2 My non >electrical mind just cannot figure that out. An alternator generally has two connections to the ship's electrical system. (1) The "B-Lead" or battery lead that is a power-output connection and an input lead that is (2a) excitation from the regulator to the field . . . Emacs! . . . or (2b) on/off control to the internal regulator. Emacs! In both cases, you can see that the B-lead connects to the + side of a three-phase rectifier . . . diodes that convert the internally generated AC into DC while preventing any back flow of current from the battery into the alternator. In all automotive applications, you will find that the b-lead is always connected to the vehicle's battery. The factory stock (+) battery cable for my truck comes with two wires, a fat wire to the starter solenoid and a not-so-fat wire running directly to the alternator b-lead - power never flows into this lead as long as the diodes are intact. The only 'input' lead to an externally regulated alternator draws current when the alternator control switch is ON. This is field current from the regulator attempting to control bus voltage. If the engine is not yet running, the regulator will 'full field' the alternator causing as much as 3 amps of draw on the battery. The modern internally regulated alternator often features an integrated circuit that 'watches' for the presence of ac voltage from the stator windings. If no AC present then the alternator is not rotating . . . and field current is shut off. This prevents the otherwise inevitable, non-productive drain during times the engine is not running. >It's been 5 years since I retired, but I do >remember some screen interruption, all be it >small and fast during engine starts on some if >not all the planes I flew to make a buck.=C2 Usually when changing from >APU power to the engine driven generators. =C2 I >guess its just part of the program Correct. This is a function of time-to-boot-up inherent in the design of the appliance. As I recall, all of the screens in the line of Beech products pretty much came alive in a second or less after application of operating power whether first-on or post brown-out . . . so we KNOW it can be done. All of my software driven products are wide-eyed, bright-eyed and bushy-tailed milliseconds after power up. But ever since the Blue Mountain days of EFIS products offered to owner built and maintained aircraft, there have be a variety of instances where boot-up times were sometimes distressingly long (Blue Mountain had a HARD DRIVE!!). So not only did that product need to load an operating system, it might take many seconds after the software woke up until the analog rate integration calculations could get stood up in deducing the gravity vector. We've come a long way baby . . . but it's still disappointing that some of the big guns in the electronic instrumentation business for light aircraft are not not implementing the best we know how to do in managing power-up/brown-outs events. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:04:10 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltage drop At 06:59 PM 8/20/2016, you wrote: > >The only situation I have experienced where oil pressure response >time was important is for a cold start, as in below freezing, where >the amount of pre-heat is questionable as to whether it was applied >long enough. As in if pressure doesn't come up in 30 seconds, one >should shut down and apply heat longer to the engine compartment. >Seems like some electrowhizzy engine monitors take 30 seconds to >boot. On the other hand, most of them respond well to a small backup >battery that keeps input voltage high enough to prevent a reboot. Yeah. I recall getting ready to depart Kansas City one morning when the airplane had sat out in -10F weather. We heated the engine and used ground power to supplement a cold battery. Engine started readily but the oil pressure didn't really start to move for a really long time (didn't have the stop watch out). The oil pressure gage was connected to the engine through a small bore copper line. Oil in that line behind the fire wall did not get warmed in pre-heat . . . and was essentially the consistency of peanut butter. Under some circumstances, even the legacy steam gage can take some time to offer useful information. Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:49:42 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltage drop Posted this eariler and got a bounce from the ListServer about having exceeded attachment limits. Need to look into that. In the mean time, here's a repost with links to images: At 08:57 PM 8/20/2016, you wrote: >Thanks Bob, > >I do have a backup battery that is already wired >in but have it disconnected because there is no charging going on. Don't understand this . . . is this a system battery that is part of your airplane's architecture or is it associated with a specific appliance as part of its design? >=C2 The other problem is that my odyssey battery >(680) was more discharged than I thought .=C2 It >is on a charger now and it should rectify the >problem. I was just concerned I had a bad relay >or miss-wired something.=C2 The good news is I >checked all my wiring Battery/ Alt. switch etc.=C2 They were all fine. . . . good connecting of the dots . . . >I do have a basic question that I cannot seem to >answer in my mind.=C2 When the Battery switch is >on, there is power going to the alternator via >the main B lead. Since that lead is connected >directly to the output side of the battery relay >dose it not draw a significant amount of current >when the Battery master is on and the alternator >is not running.=C2 In you book it show hat=C2 lead >connected to coils that are stationary in the >alternator, then to ground believe.=C2 My non >electrical mind just cannot figure that out. An alternator generally has two connections to the ship's electrical system. (1) The "B-Lead" or battery lead that is a power-output connection and an input lead that is (2a) excitation from the regulator to the field . . . http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg . . . or (2b) on/off control to the internal regulator. http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg In both cases, you can see that the B-lead connects to the + side of a three-phase rectifier . . . diodes that convert the internally generated AC into DC while preventing any back flow of current from the battery into the alternator. In all automotive applications, you will find that the b-lead is always connected to the vehicle's battery. The factory stock (+) battery cable for my truck comes with two wires, a fat wire to the starter solenoid and a not-so-fat wire running directly to the alternator b-lead - power never flows into this lead as long as the diodes are intact. The only 'input' lead to an externally regulated alternator draws current when the alternator control switch is ON. This is field current from the regulator attempting to control bus voltage. If the engine is not yet running, the regulator will 'full field' the alternator causing as much as 3 amps of draw on the battery. The modern internally regulated alternator often features an integrated circuit that 'watches' for the presence of ac voltage from the stator windings. If no AC present then the alternator is not rotating . . . and field current is shut off. This prevents the otherwise inevitable, non-productive drain during times the engine is not running. >It's been 5 years since I retired, but I do >remember some screen interruption, all be it >small and fast during engine starts on some if >not all the planes I flew to make a buck.=C2 Usually when changing from >APU power to the engine driven generators. =C2 I >guess its just part of the program Correct. This is a function of time-to-boot-up inherent in the design of the appliance. As I recall, all of the screens in the line of Beech products pretty much came alive in a second or less after application of operating power whether first-on or post brown-out . . . so we KNOW it can be done. All of my software driven products are wide-eyed, bright-eyed and bushy-tailed milliseconds after power up. But ever since the Blue Mountain days of EFIS products offered to owner built and maintained aircraft, there have be a variety of instances where boot-up times were sometimes distressingly long (Blue Mountain had a HARD DRIVE!!). So not only did that product need to load an operating system, it might take many seconds after the software woke up until the analog rate integration calculations could get stood up in deducing the gravity vector. We've come a long way baby . . . but it's still disappointing that some of the big guns in the electronic instrumentation business for light aircraft are not not implementing the best we know how to do in managing power-up/brown-outs events. Bob . . . Bob . . . ________________________________ Message 4 _____________________________________ Time: 09:19:43 AM PST US From: ashleysc@broadstripe.net Subject: Re: AeroElectric-List: Voltage drop Hi Bob; Neat and very understandable schematics for externally and internally regul ated alternators. Would you care to provide one for a internally regulated, permanent magnet alternator, so as to cover the subject exhaustively? I th ink I can deduce same, but would feel better to have it "from the horse's m outh." Cheers!=C2-=C2- Stu. ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Sunday, August 21, 2016 7:57:50 AM Subject: Re: AeroElectric-List: Voltage drop Posted this eariler and got a bounce from the ListServer about having exceeded attachment limits. Need to look into that. In the mean time, here's a repost with links to images: At 08:57 PM 8/20/2016, you wrote: Thanks Bob, I do have a backup battery that is already wired in but have it disconnecte d because there is no charging going on. =C2- Don't understand this . . . is this a system =C2- battery that is part of your airplane's architecture =C2- or is it associated with a specific appliance =C2- as part of its design?
=C3=82=C2- The other problem is that my odyssey battery (680) was more di scharged than I thought .=C3=82=C2- It is on a charger now and it should rectify the problem. I was just concerned I had a bad relay or miss-wired s omething.=C3=82=C2- The good news is I checked all my wiring Battery/ Alt . switch etc.=C3=82=C2- They were all fine.
=C2-=C2- . . . good connecting of the dots . . .
I do have a basic question that I cannot seem to answer in my mind.=C3=82 =C2- When the Battery switch is on, there is power going to the alternato r via the main B lead. Since that lead is connected directly to the output side of the battery relay dose it not draw a significant amount of current when the Battery master is on and the alternator is not running.=C3=82=C2 - In you book it show hat=C3=82=C2- lead connected to coils that are st ationary in the alternator, then to ground believe.=C3=82=C2- My non elec trical mind just cannot figure that out.
=C2- An alternator generally has two connections =C2- to the ship's electrical system. (1) The "B-Lead" =C2- or battery lead that is a power-output connection =C2- and an input lead that is (2a) excitation from the =C2- regulator to the field . . . http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg =C2-. . . or (2b) on/off control to the internal =C2-regulator. http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg =C2- In both cases, you can see that the B-lead =C2- connects to the + side of a three-phase =C2- rectifier . . . diodes that convert the =C2- internally generated AC into DC while =C2- preventing any back flow of current from =C2- the battery into the alternator. =C2- In all automotive applications, you will find that =C2- the b-lead is always connected to the vehicle's =C2- battery. The factory stock (+) battery cable for =C2- my truck comes with two wires, a fat wire to the =C2- starter solenoid and a not-so-fat wire running =C2- directly to the alternator b-lead - power never =C2- flows into this lead as long as the diodes =C2- are intact. =C2- The only 'input' lead to an externally regulated =C2- alternator draws current when the alternator =C2- control switch is ON. This is field current =C2- from the regulator attempting to control =C2- bus voltage. If the engine is not yet running, =C2- the regulator will 'full field' the alternator =C2- causing as much as 3 amps of draw on the =C2- battery. =C2- The modern internally regulated alternator =C2- often features an integrated circuit that =C2- 'watches' for the presence of ac voltage =C2- from the stator windings. If no AC present =C2- then the alternator is not rotating . . . and =C2- field current is shut off. This prevents =C2- the otherwise inevitable, non-productive =C2- drain during times the engine is not running.
It's been 5 years since I retired, but I do remember some screen interrupti on, all be it small and fast during engine starts on some if not all the pl anes I flew to make a buck.=C3=82=C2- Usually when changing from APU power to the engine driven generators. =C3=82=C2- I guess its just pa rt of the program
=C2- Correct. This is a function of time-to-boot-up =C2- inherent in the design of the appliance. =C2- As I recall, all of the screens in the =C2- line of Beech products pretty much came =C2- alive in a second or less after application =C2- of operating power whether first-on or =C2- post brown-out . . . so we KNOW it can =C2- be done. All of my software driven products =C2- are wide-eyed, bright-eyed and bushy-tailed =C2- milliseconds after power up. =C2- But ever since the Blue Mountain days of =C2- EFIS products offered to owner built and =C2- maintained aircraft, there have be a variety =C2- of instances where boot-up times were sometimes =C2- distressingly long (Blue Mountain had a HARD =C2- DRIVE!!). So not only did that product =C2- need to load an operating system, it might =C2- take many seconds after the software woke =C2- up until the analog rate integration =C2- calculations could get stood up in deducing =C2- the gravity vector. =C2- We've come a long way baby . . . but it's =C2- still disappointing that some of the big =C2- guns in the electronic instrumentation =C2- business for light aircraft are not not =C2- implementing the best we know how to do =C2- in managing power-up/brown-outs events. =C2- Bob . . . =C2- Bob . . . ________________________________ Message 5 _____________________________________ Time: 12:09:17 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltage drop At 11:18 AM 8/21/2016, you wrote: >Hi Bob; >Neat and very understandable schematics for externally and >internally regulated alternators. Would you care to provide one for >a internally regulated, permanent magnet alternator, so as to cover >the subject exhaustively? I think I can deduce same, but would feel >better to have it "from the horse's mouth." >Cheers! Stu. I'm not sure such a critter exitsts. The only PM alternators I'm aware of are exceedingly simple arrays of magnets rotated about a stator winding of suitable wire. Check out the images at . . . http://tinyurl.com/z27kpv4 These are PM alternators characteristic of all such products from the lowly SD-8 up through the 30A, 3-phase machines on some small tractors. Spinning magnets, stationary wires. The energy coming out of these machines is an AC current with frequency and voltage proportional to engine RPM. This is why the 'regulators' paired with these devices are more properly called RECTIFIER-REGULATORS. They must not only convert the AC to DC (like the diodes in the wound field alternators) they must CONTROL that voltage through devices that must CARRY the full load current. Hence, there are no nifty, itty-bitty regulators like those found in wound field machines . . . instead, the R-R is a rather robust device obviously designed to dissipate HEAT. It's a whole other breed of cat . . . so sayeth the north end of the northbound horse. Bob . . . ________________________________ Message 6 _____________________________________ Time: 01:08:33 PM PST US From: Art Zemon Subject: AeroElectric-List: EFIS Power Switch Folks, I am reviewing my wiring diagrams, prior to starting to assemble the wiring harness for my EFIS. I started with MGL's installation instructions, which include an On/Off power switch for the whole MGL system: display + iBox + RDAC + magnetometer + AHRS. You can see the "EFIS On-Off" switch in these three diagrams: =8B can bus 1.pdf =8B=8B can bus 2.pdf =8B=8B ibox.pdf =8B I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS? As far as current draining the battery, I am not too worried. The whole system (all five components) draws just 1.7-2.9 amps, depending on display brightness and whether or not the heaters in the magnetometer and AHRS are energized. -- Art Z. -- http://CheerfulCurmudgeon.com/ *"If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel* ________________________________ Message 7 _____________________________________ Time: 01:27:18 PM PST US Subject: Re: AeroElectric-List: Voltage drop From: Chuck Birdsall Bob, With respect to your 4th paragraph - I work in the TC maintenance side of th e aviation industry, and have seen oil delivery system failure manifest itse lf first during engine start. The majority of those times the failure was e ither maintenance-induced or were on aircraft that have sat for extended per iods with no attempt to pre-oil before starting (one of the bigger offenders in the latter in my experience has been geared, turbocharged Continentals i n Cessna 400 series aircraft, for some reason). A few, however were mechanic al failures that were clued-in by oil pressure goofiness. One of those involved a pipeline patrol aircraft whose operator said that he didn't think the engine was developing full power. He also mentioned casual ly that the oil pressure was jumping up high right away after engine start, a nd had been doing that for several flights. That little tidbit led us to the oil filter, which was chock full o metal bits. (After further clue-taking t he engine was replaced...) My take on this is that oil pressure behavior is one of several clues to eng ine health. If the behavior departs from the norm then it's time to start as king why. It's also the last chance you get to discover that after draining t he oil for an oil change, you forgot to put oil back in - before it gets tur ned into very expensive paper weights. It's why I'd recommend having some s ort of backup for use during engine start or other times when the electrical system has failed. In the TC world that's usually a backup battery (a la G 1000), but even a simple idiot light attached to an oil pressure switch woul d help. Chuck On Aug 20, 2016, at 6:06 PM, Robert L. Nuckolls, III wrote: At 11:10 AM 8/20/2016, you wrote: > The contactor normally gets a little warm--no worries there.=C3=82 > > Your battery is probably just fine. My 925 does=C3=82 the same thing.=C3=82 > > You'll need some kind of back-up battery to prevent what you're describing . I use one from TCW that works great. Oops . . . I stubbed my toe here. If you have any electro-whizzies that reboot when presented with a bus voltage below 11.0 volts . . . then they almost certainly will reboot every time you start the engine. I'm somewhat chagrined that folks who build and qualify these panel mounted super-computers don't either (1) study the real world of bus voltage behaviors during engine start and/or (2) advise the customer that their product WILL reboot during a start-up transient that has ALWAYS existed on EVERY airplane. To my mind, the simplest work-around is simply not to turn on . . . or depend on these gizmos until after engine start. Yeah, I know, our instructors taught us to concentrate on the oil pressure display after engine start with a finger on the mag switches lest the pressure not come up as expected. But I would be interested to hear if anyone on this list has ever experienced an failure of oil circulation that did not manifest until right after start up. No doubt, Lindbergh and contemporaries had good reason to worry about such things. Those guys carried tool boxes around in the rear cockpit with an eye toward needing off field maintenance of one kind or another. Now we have a new suite of technology which, for reasons we'll never know, was NOT designed to replace legacy instrumentation. DO-160 requires a qualified product to (1) not be damaged by and (2) recover gracefully from bus voltage brownouts quantified in the test requirements document. Problem is, graceful recovery has not been interpreted to mean that the oil pressure display on the glass screen needs to be as available and responsive as their steam gage counterparts during the first few seconds after engine start. This leaves the system integrator (YOU) with a problem. If you're going to pay homage to the legacy philosophy for monitoring engine parameters that were of intense interest to Charles Lindbergh, then we have to ADD power supply brown-out buffers for these new electro-whizzies . . . that COULD have been designed to accommodate such brown-outs. The question becomes, are we adding cost, weight and complexity to a system striving to honor a operating practice that has been around since Lindbergh? What are the demonstrated risks for cranking up an engine 'blind' an waiting for the 'new' technology to wake up and report for duty? Bob . . . ________________________________ Message 8 _____________________________________ Time: 05:13:56 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltage drop At 03:24 PM 8/21/2016, you wrote: >Bob, > >With respect to your 4th paragraph - I work in the TC maintenance >side of the aviation industry, and have seen oil delivery system >failure manifest itself first during engine start. The majority of >those times the failure was either maintenance-induced or were on >aircraft that have sat for extended periods with no attempt to >pre-oil before starting (one of the bigger offenders in the latter >in my experience has been geared, turbocharged Continentals in >Cessna 400 series aircraft, for some reason). A few, however were >mechanical failures that were clued-in by oil pressure goofiness. Yes, aviation has been plagued with numerous examples of engines that operated on the edge of self destruction . . . the C175 engines come to mind also. But again, what are the probabilities that upon starting an engine predominant in OBAM aviation aircraft that it will present with a loss of oil pressure . . . given that it taxied an airplane to parking in the not too distant past? Further, an aviation maintenance career puts you in situations like doctors . . . who never see anyone but sick people. My last five years at Beech concentrated on a series of seemingly intractable difficulties . . . but for every airplane I touched, there were thousands that did not need or would benefit from my attention. >My take on this is that oil pressure behavior is one of several >clues to engine health. If the behavior departs from the norm then >it's time to start asking why. It's also the last chance you get to >discover that after draining the oil for an oil change, you forgot >to put oil back in - before it gets turned into very expensive paper weights. But do the FMEA on these hypothetical scenarios. It's one thing that a particular engine/airframe combination has a history of difficulties related to loss of oil pressure . . . is anyone here on the List flying such a machine? Forgetting to put the oil in . . . any owner/op at elevated risk for such errors has dozens of opportunities for equal if not or more hazardous examples of absent minded events. If anyone is truly concerned about immediate notification of oil pressure after start up, I suggest that an oil pressure switch and warning light would be a simpler, lower cost, lighter weight and nearly zero maintenance solution compared with any sort of battery installation. Such switches are not subject to the effects of brown-out. Bob . . . ________________________________ Message 9 _____________________________________ Time: 06:19:14 PM PST US From: Jim Baker Subject: Re: AeroElectric-List: Voltage drop Learned to fly a J3 with my Dad as the instructor. Even the old C65 was prone to startup oil pressure issues. Had to watch carefully to see if pressure would develop immediately after the hand prop. If not, you'd have to pull the pressure line off the back of the pump and prime it with a squirt can so the gears would have something to work with. Jim Baker 405 426 5377 -----Original Message----- From: "Robert L. Nuckolls, III" Sent: Sun, 21 Aug 2016 20:12 Subject: Re: AeroElectric-List: Voltage drop --=====================_632832515==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed At 03:24 PM 8/21/2016, you wrote: >Bob, > >With respect to your 4th paragraph - I work in the TC maintenance >side of the aviation industry, and have seen oil delivery system >failure manifest itself first during engine start. The majority of >those times the failure was either maintenance-induced or were on >aircraft that have sat for extended periods with no attempt to >pre-oil before starting (one of the bigger offenders in the latter >in my experience has been geared, turbocharged Continentals in >Cessna 400 series aircraft, for some reason). A few, however were >mechanical failures that were clued-in by oil pressure goofiness. Yes, aviation has been plagued with numerous examples of engines that operated on the edge of self destruction . . . the C175 engines come to mind also. But again, what are the probabilities that upon starting an engine predominant in OBAM aviation aircraft that it will present with a loss of oil pressure . . . given that it taxied an airplane to parking in the not too distant past? Further, an aviation maintenance career puts you in situations like doctors . . . who never see anyone but sick people. My last five years at Beech concentrated on a series of seemingly intractable difficulties . . . but for every airplane I touched, there were thousands that did not need or would benefit from my attention. >My take on this is that oil pressure behavior is one of several >clues to engine health. If the behavior departs from the norm then >it's time to start asking why. It's also the last chance you get to >discover that after draining the oil for an oil change, you forgot >to put oil back in - before it gets turned into very expensive paper weights. But do the FMEA on these hypothetical scenarios. It's one thing that a particular engine/airframe combination has a history of difficulties related to loss of oil pressure . . . is anyone here on the List flying such a machine? Forgetting to put the oil in . . . any owner/op at elevated risk for such errors has dozens of opportunities for equal if not or more hazardous examples of absent minded events. If anyone is truly concerned about immediate notification of oil pressure after start up, I suggest that an oil pressure switch and warning light would be a simpler, lower cost, lighter weight and nearly zero maintenance solution compared with any sort of battery installation. Such switches are not subject to the effects of brown-out. Bob . . . --=====================_632832515==.ALT Content-Type: text/html; charset="us-ascii" At 03:24 PM 8/21/2016, you wrote:
Bob,

With respect to your 4th paragraph - I work in the TC maintenance side of the aviation industry, and have seen oil delivery system failure manifest itself first during engine start.  The majority of those times the failure was either maintenance-induced or were on aircraft that have sat for extended periods with no attempt to pre-oil before starting (one of the bigger offenders in the latter in my experience has been geared, turbocharged Continentals in Cessna 400 series aircraft, for some reason). A few, however were mechanical failures that were clued-in by oil pressure goofiness.
Yes, aviation has been plagued with numerous
examples of engines that operated on the edge
of self destruction . . . the C175 engines
come to mind also. But again, what are the
probabilities that upon starting an engine
predominant in OBAM aviation aircraft that
it will present with a loss of oil pressure
 . . . given that it taxied an airplane to
parking in the not too distant past?

Further, an aviation maintenance career
puts you in situations like doctors . . .
who never see anyone but sick people.
My last five years at Beech concentrated
on a series of seemingly intractable
difficulties . . . but for every airplane
I touched, there were thousands that did
not need or would benefit from my attention.

My take on this is that oil pressure behavior is one of several clues to engine health. If the behavior departs from the norm then it's time to start asking why. It's also the last chance you get to discover that after draining the oil for an oil change, you forgot to put oil back in - before it gets turned into very expensive paper weights.
But do the FMEA on these hypothetical scenarios.
It's one thing that a particular engine/airframe
combination has a history of difficulties related
to loss of oil pressure . . . is anyone here on
the List flying such a machine? Forgetting to
put the oil in . . . any owner/op at elevated
risk for such errors has dozens of opportunities
for equal if not or more hazardous examples of
absent minded events.

If anyone is truly concerned about immediate
notification of oil pressure after start up,
I suggest that an oil pressure switch and
warning light would be a simpler, lower cost,
lighter weight and nearly zero maintenance
solution compared with any sort of battery
installation. Such switches are not subject
to the effects of brown-out.


  Bob . . . --=====================_632832515==.ALT-- --=====================_632832515==.ALT-- ________________________________ Message 10 ____________________________________ Time: 07:16:27 PM PST US From: ashleysc@broadstripe.net Subject: Re: AeroElectric-List: Voltage drop Hi Bob; One such critter is DB Electrical APM0009, which is a 12 V., 20 Amp, intern ally regulated permanent magnet alternator. Cheers!=C2-=C2- Stu. ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Sunday, August 21, 2016 11:17:35 AM Subject: Re: AeroElectric-List: Voltage drop At 11:18 AM 8/21/2016, you wrote: Hi Bob; Neat and very understandable schematics for externally and internally regul ated alternators. Would you care to provide one for a internally regulated, permanent magnet alternator, so as to cover the subject exhaustively? I th ink I can deduce same, but would feel better to have it "from the horse's m outh." Cheers!=C2-=C2- Stu. =C2-=C2- I'm not sure such a critter exitsts. =C2-=C2- The only PM alternators I'm aware =C2-=C2- of are exceedingly simple arrays of =C2-=C2- magnets rotated about a stator winding =C2-=C2- of suitable wire. Check out the images =C2-=C2- at . . . http://tinyurl.com/z27kpv4 =C2-=C2- These are PM alternators characteristic =C2-=C2- of all such products from the lowly SD-8 up =C2-=C2- through the 30A, 3-phase machines on some =C2-=C2- small tractors. =C2-=C2- Spinning magnets, stationary wires. =C2-=C2- The energy coming out of these machines is =C2-=C2- an AC current with frequency and voltage =C2-=C2- proportional to engine RPM. =C2-=C2- This is why the 'regulators' paired with =C2-=C2- these devices are more properly called =C2-=C2- RECTIFIER-REGULATORS. =C2-=C2- They must not only convert the AC to DC =C2-=C2- (like the diodes in the wound field =C2-=C2- alternators) they must CONTROL that voltage =C2-=C2- through devices that must CARRY the full =C2-=C2- load current. Hence, there are no nifty, =C2-=C2- itty-bitty regulators like those found in =C2-=C2- wound field machines . . . instead, the R-R =C2-=C2- is a rather robust device obviously designed =C2-=C2- to dissipate HEAT. =C2-=C2- It's a whole other breed of cat . . . so =C2-=C2- sayeth the north end of the northbound =C2-=C2- horse.=C2-=C2-=C2-=C2-=C2-=C2-=C2- =C2-=C2- =C2-=C2-=C2-=C2-=C2-=C2- =C2- Bob . . . ________________________________ Message 11 ____________________________________ Time: 07:29:53 PM PST US Subject: AeroElectric-List: Re: EFIS Power Switch From: "user9253" > I am honestly not sure that I want this switch. Is there ever a time when I would have the master switch on but not want power to the EFIS? The pilot should have the ability to shut off each and every electrical load. If the MGL units have their own switches, than an additional switch is not necessary. If the MGL malfunctions or gives off smoke, there should be a way to shut it off without shutting off everything else. On the other hand, if you do not mind shutting off the master switch if necessary, it is not a big deal. Builders of experimental aircraft can wire the airplane to meet their goals. As long as it is not dangerous, do it the way you want. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=459733#459733 ------------------------------------------------------------------------------------- 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.