Charging Problem/ Gear problem

[Dale Campbell]

I finally got my charging problem fixed after chasing it for 1.5 years. The problem was intermittant lights blinking, front & rear charge lights blinking. And landing gear not locking down at times. We had replaced, all 3 contacter, large & small diodes, large capacitors, battery, checked for loose wires & voltage drops across circuit breakers. Replace 1 lord coupler on alternator. We also changed both voltage regulators. We installed a new parrallel regulator system. The way we found the problem is the rear alternator finally totally failed. The brushes where hanging up. This also made the gear problem. On a 337H you have a power pack gear pump that demands a lot of power at the end of the gear down cycle. At that moment the rear alternator would stop putting out. Also I was down wind on landing, so the engines where at very low RPM. Not giving out enough power to complete gear down cycle.

[SkyKing]

Dale,

Whoah... you lost me. Exactly what did you identify as the culprit? Something doesn't jive with your story here... the battery, if in good shape, together with just one alternator would have more than ample capacity to cycle the gear up or down into locked positions, as it is a pressure switch that turns off the power pack, not high current. When you say the brushes "hung-up", what do you mean? Either the brushes are working ... or they're not.

Sometimes you will get a very brief, intermittant, alternator NOT CHARGING yellow light showing up when your electrical load is light, or the RPM's aren't synched up because it IS a parallel system, not in series, and the alternators are sharing the load. You can shut one alternator down using the alternator split rocker switches and proceed with a flight without a problem.

A battery doesn't necessarily have to be changed out, but more importantly, REGULARLY SERVICED, checking fluid levels and specific grafity of each cell. A volt-ohm meter is also useful in checking the battery voltage in between flights. Nominal voltage will be 23 volts, so anything above is usually indicative of a good battery... but ALWAYS check the fluid level until some history of use is determined, and using distilled water ONLY, keep the level at the "rings" in each cell. If you don't fly the airplane at least every couple of weeks, it will naturally discharge just from just sitting.

Did you know that a "dirty" battery will discharge itself? Yes, electroytic solution not properly washed off and neautralized around the battery top can discharge the battery. Always clean the battery out of the ship by flushing it with a solution of baking soda, and then fresh water, making sure that none of this enters the battery vents.

Before the connections are made, use some petroleum jelly around all of the terminals, screw threads, nuts, washers and contacts... this will help in preventing self-discharge and also keep the connections electrically sound.

Every couple of weeks, check the battery voltage with a VOM across the battery contactor and ground. And keep your battery conditioned by placing a trickly charge on it every few weeks if the airplane is being flown infrequently. Doing this will keep your battery in tip-top shape and your battery will outlast most everyone else's.

My last Gill 242 lasted for SIX long years. And another battery that was discarded by someone who didn't have knowledge of batteries... well, his gave up the ghost after a year, primarily because he never check the fluid level. He was endured to the FBO for $250 for a replacement & install... meanwhile I was able to get hold of the old one, rejuvenate it and currently use it for a serviceable spare. What you don't know can COST you a bundle.

SkyKing

[SkyKing]

BTW, in order to preserve your engines, make more practicable use of the airspace at your airport, and confirm correct operation per the checklist, it's NOT a good idea to wait until you're almost on the gound, i.e., when you're "downwind"... to lower the gear --this should always be done BEFORE entering the traffic pattern. By doing so you have time to confirm via checklist that everything is as it should be, enter the pattern and sequence yourself with other traffic, and the plane slowed up and RPM's "UP" instead of down in the bottom groveling along.

As the TCM Engine Manual for the TSIO-360 engine cautions: "DO NOT PERMIT CYINDER TEMPERATURE TO DROP BELOW 240 DEGREES F." Also, the manual urges that long descents at low maniold pressure be avoided as the engines can cool excessively and may not accelerate satisfactorily when power might be needed. So it's always best to keep the RPM's spooled UP and the MP spooled up, lower the gear well before entering the pattern to be safe, and drop some flaps out. To do otherwise is asking for trouble

SkyKing

[Dale Campbell]

The components where replaced one at a time over 1.5 years. Not all at once. We where chasing a intermittant problem it was there and then it disappeared. First one alternator would go off line, than the next time the other would go off line. Lights always blinking. The Parallel regulators, new system, was just installed 2 days ago, with the new rear alternator. The A&P told me that the alternator failed internally & the brushes would hang, also something came loose inside alternator. That is the alternator that had the lord coupler changed last year. The landing gear down locks now snap in much faster & the blinking lights stopped.
To answer another question. My home base is uncontrolled with mountains on three sides 2,000 feet above runway. I start cooling engines 10 minutes out, get most of items checked on check list , get first knotch of flaps out before desending over mountains to airport, get speed down to 100 knots, drop gear down as I turn down wind. Thats the way I have been trained by instructor. He has owned a 337 for over 10 years, a 25,000 hour pilot. What more can I tell you.