Thursday 23 May 2013 13:16 UTC
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We appear to have a alternator which is refusing to charge the battery.
Did I discover this on the ground by following the checklist item which says "Ammeter charging?"
Nope. Or if I'm entirely honest: "Well... Yes....Almost... but then I convinced myself I was wrong..."
So I discovered it in the air instead, during the first set of checks after levelling off. Low Volt light still on and the Ammeter lifeless on zero no matter what I turn on and off.
So how did I come to convince myself it was fine on the ground?
Point one - I've flown several aeroplanes where the low volt light flickers a bit when the engine is running slowly. That didn't immediately stand out to me as a problem and I didn't look at it again during the powerchecks.
Point 2 - I'm far less familiar with this aircraft and what 'normal' is. I did look at the ammeter and was mildly surprised it wasn't registering "much" (or "at all" in reality!) and I should with perfect hindsight have realised that it was actually dead flat on 0 rather than merely 'not showing much'.
I should have done my turning off and on of things and recycling of the master switch at that point but I didn't. I convinced myself I wasn't seeing what I was seeing and off I went.
Undramatic of course because I had presumably a more or less fully charged battery and was only ten minutes out so I just came back again. Fiddled a bit more on the ground, enlisted a few more pairs of eyes to help me look for an obvious physical cause and then gave up ad came home to break the bad news to the group that there's probably another bill coming.
Far too easy though to convince myself I wasn't seeing a problem when there was one there staring straight at me with a perfectly clear set of symptoms.
It doesn't help that the ammeter on a PA28 is in front of the RH seat so from the LH, parallax makes the needle read higher than it really is.
I don't know how instructors & others can fly from the RHS when the instruments are offset so much...
Go up with someone and have a go, it's not that big a deal!
If Timothy had his way, you would know me as Daniel.
Hadn't thought about the parallax, although have noticed it with the tacho.
One of the lads in the shareoplane group informs me it's conspicuous when the ammeter's working because it 'bounces' in time with the strobes!
My ammeter has never worked reliably so I have to rely on the low volts light and if it's on at power check time, that's a no fly indication in spades
Extremely grumpy PPL/IR
If it's like my ammeter, it'll still do that if the alternator isn't working. The indication that something's up is the "low volts" light, as johnm says.
Moderatio in omnibus
The Warrior ammeter only reads charge current, so if the alternator fails it goes straight to zero. I know this because it happened N of Stockholm and the very helpful controllers noted my cell phone number in case I had a complete power failure whilst en-route to my diversion, allowing me through Arlanda airspace with the xpndr switched off!
Otherwise, the flicking caused by the strobes is a useful health check and I am now in the habit of checking the landing light during run-up, just to be sure the ammeter moves and I don't take off having forgotten it!
Does the ammeter read 'Charge Current' that which goes to the battery OR
Load current that which comes from the alternator to all points electrical
An ammeter which is set up to read 'Charge current' is Centre Zero and reads both charge -- current into the battery and Discharge--current out of the battery.
The Load type ammeter (most American types) only tells you the load on the alternator --
Which with a normal load of radios-lights - Strobes etc -- Should be reading something at all times during a flight, if the alternator is OK.
If this type is reading Zero then all the electrical power is coming from the battery -- but this type of ammeter will not show that discharge current.
Beagle Pup 150. flywales.flyer.co.uk
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