These are examples of components often encountered on GA aircraft. The Lamar regulator is clearly marked and it can be easily seen what it is all about. They are often found on Piper singles, and throughout the range at that.
The overvolt unit can be seen on Cessna's and even some Islanders.
They are not precision devices, - the operating points (voltages) can be somewhat variable and indeed the Lamar depicted is adjustable.
T28D -C'mon Creamie say something profound about how the Law is protecting us all.
I ask, as a [20,000 hour plus, (15,000 + Command) veteran], what?, in the way of technical, operational advantage; or skill improvements has CP ever offered. The answer is of course 'por nada'.
We are, of course kind to a brother 'amateur' pilot: (as clearly this is) but then again, you have to ask – would you (considering it's track record) put you and yours in these hands?. Short answer NO. The rest I leave up to your discretion.
Refer to it's previous posts related to aerodynamics, engines, electrics etc. etc.
His imagined (friends) AKA CASA cohorts (and Brothers in exile), can they really provide the answers it truly seeks?; ask any professional pilot in Australia about CASA flying/ on line operatational abilities (under privilege of course) – they will, in no uncertain terms give an answer, under OATH during 'in camera' testimony.
Not usually one to give advice, but; – CP ; in my tribe, it is considered that more knowledge can be gained with mouth firmly closed and ears open; than in any other way.
T28D, as I suggested above, I reckon most of that protection is now concealed in an area the size of of a key on a keyboard including a relay, SSR of course.
The modern surface mount board
Can you imagine the cost of building an old radio, say early 60's King today. An SL40 s cheap!!
The placard that is mentioned and queried in this thread is a result of CASA AD/Gen/37 amdt 3 of 9/2000.As a result of this the warning must be in place on all aircraft that fall within the AD scope. It clearly states on page 2 of the AD that "The reason for this directive is to ensure that the aircraft battery does not become flat in flight resulting in a generator not being able to produce power when selected on." The term generator in CASA speak also refers to any electrical producing unit and includes alternators.The lack of auto excitation on an alternator has already been referred to by a number of posters. This is different and really has nothing to do with why an alternator would be selected off prior to start.The only bearing that this AD would have on the original question is that if the gen/alt is left on then the chance of flattening the battery accidentally is removed.
In many Cessnas at least, when ground power is applied a number of circuits are not powered by the GP, particularly avionics.
"Many moons ago I was taught to only switch on the BATT side of the dual switches (on the Cessna's) and in the after start procedure then switch on the alternator to check that it is working in the correct sense.
Is their any merit in this system rather than switching on both at the same time prior to starting and then checking the alternator output. Maybe an engineer can shed some light if there is a technical issue at work here."
My response was to indicate that if you are out in the boondocks in a 182 with an almost flat battery, for whatever reason, you may increase the possibly of getting a start if you turn the alternator off before starting, and back on after starting of course.
This is a response from the school of hard knocks and may help someone some day.
The problem with checking an alternator after start is that the traditional instrument on aircraft for the generating system is an ammeter.With an alternator the ammeter alone is of little use. A voltmeter is much better and that is why cars and trucks have had voltmeters as standard for a long while.
On 12 volts the normal alternator output should be 13.9 to 14.5 volts. The higher the voltage output the greater load that it is handling. So a high voltage continuously may indicate a battery problem.However a low alternator amp output doesn't neccessarily indicate that the battery is happy. Generators on the other hand tell all via an ammeter.
Its a mystery as to why aircraft which use similar alternators to automotive stick to ammeters. Wunwing
To answer Flywatchers question. Firstly if the battery is suspected of being flat, indeed marginal for a start, then there is one switch you would not operate. Sure load share as much as you can with the pre-start routine. Alternator and avionics master off.
Now this is where you need to know your aircraft... the one switch I would not be touching is the starter ! That can make life very difficult, indeed possibly a show stopper.
I will have to generalise as we can't cover all aircraft or engine types.. On something like a Lycoming O-320 and up to O-540's you may get a satisfactory swing start. Once the starter has been operated a failed start will mean the Bendix will remain engaged. Many Pilots have no idea how to swing start an engine safely, or correctly. Swinging a prop with the Bendix engaged makes the job so much more difficult, - indeed next to impossible on the bigger engines.
I am not even happy swinging a Tomahawk with the starter Bendix engaged.
So on certain aircraft and you think you may have a marginal battery the best thing to do would be to break out the cellphone and ring the LAME. Leave ALL switches in the aircraft off.. Don't even hit the starter, Alternator switched off or not.
Now back to the question about where to have the switches during a normal start.. I would be reading the POH and listening just a little to the instructor. If there is any difference then it would be time to quiz the instructor a little more about it.
Firstly if the battery is suspected of being flat, indeed marginal for a start, then there is one switch you would not operate.
(trimmed) Now this is where you need to know your aircraft... the one switch I would not be touching is the starter ! That can make life very difficult, indeed possibly a show stopper.
(trimmed)
. Once the starter has been operated a failed start will mean the Bendix will remain engaged.
Agreed, but you forgot the other problem associated with marginal batteries <reffered to as MB from here on in.
How many pilots/car drivers have you seen attempting an MB start where it struggles through the compression, or even worse tapping the starter button until it finally gives up and goes through the compression? I bet not one of these people realise just how much damage they are doing to the starters internals, and potentially to the battery itself.
LAME's bank accounts love these dopes.
Quote:
Many Pilots have no idea how to swing start an engine safely
I'll cheerfully put myself in this category. Aware of the dangers, aware of the cockpit drill (for 2 person swinging). Something I might go and learn sometime.
Quote:
So on certain aircraft and you think you may have a marginal battery the best thing to do would be to break out the cellphone and ring the LAME. Leave ALL switches in the aircraft off.. Don't even hit the starter, Alternator switched off or not.
Or if you have the equipment, and knowledge, then go GPU and end the MB situation.
Quote:
Now back to the question about where to have the switches during a normal start.. I would be reading the POH and listening just a little to the instructor. If there is any difference then it would be time to quiz the instructor a little more about it.
I prefer to ask questions like these of several instructors as a group, then kick back with a beer to enjoy the fireworks. Then check what I learned with a LAME.
We had a conversation about this very thread at the aeroclub on sunday, and I thought now was an oppurtune time to recheck my thoughts....so opened my travel-air manual to x-check my recollections of the procedures and why.
The Be95, has 2 big arse ALT FAIL lamps set high on the coaming. In the pre-start, you use the Test button to make sure they light up. To keep it simple...
.....Master on. Alt on Alt warning lamp should illuminate. Light the fire Alt lamp should extinguish Check amp metre, once it falls to its lowest point, light 2nd fire.
Doing it this way shows that the failure warning circuit is working as advertised.
If you start it with the alternator off, the fail lamp will never show you if the warning system is working.
The AD is actually CASA AD/Gen/39 amdt 3 of 9/2000.
What is interesting also is the comment that the previous revision, Amend 2, was issued in Nov 1967... and the reasons and changes from the original are unknown.
That is very much what I expected. Many of these AD's are historic... based on an event so far back that no-one is even too sure what brought it all on at that time. It takes even more input now to go and research everything for the AD to be cancelled or otherwise amended.
It all goes back to an FAA Advisory Circular, dated 1965. AC20.40
At that time many pilots were possibly used to self exciting generators. These days it is the exact opposite, as we have already mentioned the alternator is commonplace. Commonsense and training will tell us that the alternator will not come online with a flat battery.
BACKGROUND: Since an alternator is but one class of generator, approval of alternator installation in light aircraft have been made by the Agency under those rules in FAR 23 and 27 which deal with generator systems. It has been found, however, that certain types of alternators
(which are apparently used in a number of automotive applications) obtain their field excitation from the battery. When field excitation is obtained in this way, there is the danger that, if the alternator is turned off in flight, subsequent loss or discharge of the battery would result in Loss of the alternator as well. This unusual design feature invokes the provisions in @23.1541(a)(2) and 27.1541(a)(2). ACCEPTABLE MEANS OF COMPLIANCE: With respect to battery-excited alternator instarlations, an acceptable method of complying with 6823.l.S41(a)(2) and 27.1541(a)(2) is to provide a placard advising the pilot not to turn off the alternators in flight, except in case of emergency
Last edited by baron_beeza; 27th Jun 2012 at 22:43.
If you aircraft has an external power port then I suggest you should start asking questions about the whereabouts of the jumper leads.
It is not difficult tp make a set and well worth the effort... especially if your aircraft already has the socket.
The Piper plug is not that expensive.
I have made a number of these up for owners over the years and still have spare sets. I am also putting together kits to modify Piper Cherokees and the likes to install the PEP receptacle.
The jumper leads just require a car to get you going again. That has to be much safer than the alternatives. Crawling into the battery compartment with a set of automotive jumper cables is not a safe alternative.
I don't even charge aircraft batteries in-situ.
If you want lessons on prop swinging you really do need a good instructor.. I mean possibly a LAME. So many guys get it wrong. Many get away with it but just do a Google and see how many aircraft actually do get damaged. The accident rate is staggering.
If you are not qualified to swing a prop then don't even consider it. Drag out the mobile instead.. The best advice I can offer I am afraid guys.
Oh, and do check to see if your aircraft takes external power. If it does the get out the leads and go out through the drill.
Last edited by baron_beeza; 29th Jun 2012 at 02:44.
The Be95, has 2 big arse ALT FAIL lamps set high on the coaming. In the pre-start, you use the Test button to make sure they light up. To keep it simple...
.....Master on. Alt on Alt warning lamp should illuminate. Light the fire Alt lamp should extinguish Check amp metre, once it falls to its lowest point, light 2nd fire.
Doing it this way shows that the failure warning circuit is working as advertised.
If you start it with the alternator off, the fail lamp will never show you if the warning system is working.
The Chieftain is similar and goes even further in that the master switch is both battery and alternators linked together, this is due to how the electrical system load shares. The split switch allows an individual alternator (field) to be switched off at a time but not both at once without switching off the battery. In the event of dual alternator failure the alternator field breakers must be opened which are separate to the master switch. Starting each side with its respective alternator off would require juggling switches and breakers. Most operators already come up with ingenious ways of starting chieftains using pulled boost CBs, mixture at various settings, flicking fuel aux pumps and so on without adding alternators to the list.
Checking whether an individual alternator is doing its job can be achieved a similar way to how the individual hydraulic pumps are checked. That is after one engine is started check fail light and battery charge status (ammeter load) same as the gear handle hydraulic check is completed. Shutdown in same order as start and check systems on other engine. Inbetween the failure lights and ammeter should provide sufficient indication of problems.
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then kick back with a beer to enjoy the fireworks. Then check what I learned with a LAME. 
