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Hi Pete
I'll take it one at at time for your answers IN DIFFERENT TEXT
GMAs
It is not my intention to talk out of turn here but I will make some comments on your trouble shooting ideas, and the little quiz.
I do not think a simple volt meter is good enough to start measuring voltages and resistance as they are not accurate and libel to errors. As i have seen when measuring across a circuit breaker you will need to load it as a bad connection inside the breaker would not show until loaded.
TRUE. I WAS ASSUMING THAT YOU MEASURE THE ITEM WHILE ITS IN OPERATION... THAT IS HOW WE DO IT HERE... UNLESS YOUR DOING A STATIC CHECK. VOLTMETERS ARE ONE OF THE BETTER TOOLS TO DO ANY TROUBLE SHOOTING OF ELECTRONIC/PLANE CKTS. ONE WITH A CONTENUITY CHECKER BUILT IN (TONE OR BUZZER) IS EVEN BETTER FOR CHECKING WIRES AND SWITCHES BECAUSE YOU DON'T HAVE TO LOOK AT THE THING. WE ALSO USE O-SCOPES TO LOOK AT THE ELECTRICAL TRACINGS AND FOR CHECKING MAGS.... THEY ARE EXPENSIVE AND MOST MECHANICS ARE NOT ELECTRONICALLY TRAINED TO UNDERSTAND THEM. A GOOD VOM (EITHER DIGITAL OR ANALOG) IS THE FIRST TOOL OF CHOICE.... I DON'T KNOW HOW YOU SET VOLTAGES OR OTHER TESTING WITHOUT ONE.
On the '65 337 both alternators are fed by one regulator so you cannot compromise between the front and rear, so any oscillation problem are down to wiring, connection, and the condition of breakers etc. On all 337's with dual regulator system this is not a problem as each regulator output can be adjusted to suit.
DUAL REGULATORS WE HAVE SEEN HAVE INDIVIDUAL VOLTAGE ADJUSTMENTS BUILT INTO THEM.. AND ARE ADJUSTABLE ONCE INSIDE. IF YOUR SINGLE REGULATOR IS SETTING ACROSS BOTH FIELDS.. THE FIRST THING I WOULD DO IS UPGRADE IT TO A DUAL SPLIT... OR YOU WILL ALWAYS HAVE PROBLEMS ...BOTH ALTERNATORS WILL NOT PERFORM THE SAME ALL THE TIME... NO MATTER HOW HARD YOU TRY.
By the way GMAs what should be the voltage at the alternator field on a '65 337 and just for fun what should it be on the '77 337, just a little quiz for you all.
AHHH TRICK QUESTION THEIR PETE.... WHAT VOLTAGE SHOULD THE BATTERY BE CHARGED AT IS MORE THE RIGHT RESPONSE... CHECKING THE MANUFACTURES MANUAL IS THE PROPER ANSWER.. AS SETTING IT TO WHERE HE WANTS FOR HIS BATTERY IS THE CORRECT REPLY... (CESSNA HAS SOME GOOD READING MATERIAL IN ITS SERVICE MANUAL ON THIS SUBJECT)
You seem to go a lot for the master or starter relays, and your failure rate seems high and over here we have 30-40 year old aircraft flying quite ok and never had a relay go down. Most of the Cessna range use this relay with no problems.
WELL... CHECKING THE MANUFACTURS (CESSNA) IT SAYS THAT THEY SHOULD BE REPLACED EVERY 5 YEARS. NOW I KNOW A LOT OF OWNERS WHO HAVE NOT REPLACED THEM SINCE THE FACTORY... I ALSO SEE A LOT OF THEM THAT BURN UP STARTERS WHEN THEY HANG AND OR LOTS OF PROBLEMS WITH OTHER ELECTRICAL ISSUES WHEN THE MASTER SELO IS ...OLD. MOST OF THE TIME THE OWNERS FOLLOW THE MANUFACTURES SUGGESTED INSTRUCTIONS TO KEEP FROM HAVING PROBLEMS. OTHERWISE WHY WOULD THEY WRITE IT???
Change a battery after 2 years, no way, to expensive and not necessary if the battery is maintained properly.
WELL... AGAIN MAYBE THEY DO IT THAT WAY OVER THEIR.. BUT HERE ON THE LEFT COAST MOST OF THE GILL 242'S AND OTHERS DON'T MAKE THE LOAD TEST.. I.E THEY ARE LOSING CAP AFTER 2 YEARS. (NOW WHY DOES THE MANUFACTURE WANT YOU TO LOAD TEST THE BATTERY EVERY 11 MONTHS.... WELL ITS SO THAT WHEN YOU HAVE A PROBLEM YOU MIGHT JUST HAVE ENOUGH BATTERY TO MAKE IT BACK TO LAND WITHOUT CAUSING A BIG EMERGENCY) THE ISSUE OF BATTERY DEATH IS REALLY FOUND IN TWO AREAS. THE USED AND THE UN-USED. USED THE PLATES GET EATEN UP INSIDE BY USEAGE... THE UN-USED... THE BATTERY SULFATES AND IT THEN ALSO LOSES IT ABILITY TO PROVIDE THE CURRENT SPEC'ED FOR. OF COURSE RUNNING THEM LOW ON LIQUID/WATER ALWAYS HELPS SHORTEN THEIR LIFE DUE TO HEAT AND LACK OF ACID SUPPLY. (PLATE WARPING CAUSES SHORTED SECTIONS OF THE CELLS)
I WILL NOW TURN THE TABLE ON YOU PETE.... BY ASKING THIS QUESTION. HOW MANY MIN AND AT WHAT AMPERAGE SHOULD YOU BE TESTING THE BATTERY AT/ AND WHAT EQUIPMENT SHOULD BE USED TO TEST IT FOR COMPLIANCE WITH CONTENUED AIRWORTHY? (YEP ITS OPEN BOOK SO YOU CAN GO LOOK IT UP)
WHEN WAS THE LAST TIME YOU DID A LOAD TEST ON A SKYMASTER BATTERY... AND WHAT WERE THE RESULTS. (MOST MECHANICS JUST CHECKTHE LIQUID LEVEL AND CALL IT GOOD... BUT THAT IS NOT CORRECT WHEN YOU HAVE YOUR PLANE INSPECTED.
OH AND FINAL QUESTION.. WHAT / WHEN SHOULD YOU DO THE TEST ON THE BATTERY?
I AM SURE THAT IF WE CAME OVER AND TESTED 10 SKYMASTER WE WOULD FIND THAT THEY ARE FLYING WITH DEFECENT BATTERIES... AVG IS THAT 3 OUT OF 10 WILL FAIL. IT IS THEN THAT THESE PLANES ARE NOT AIRWORTHY AND BECOME A ISSUE FOR FLIGHT.
I do not understand your shotgunning is not an acceptable method, please explain.
WELL.... SHOTGUNNING IS NOT ACCEPTABLE METHODE BECAUSE FIRST OFF IT COST THE OWNER/OPERATOR TOO MUCH MONEY. SECOND ITS NOT SAFE.
SHOTGUNNING IS NOT TROUBLE FINDING. YOU ARE JUST REPLACING THE BLACK BOX THAT FAILED... YOU DON'T KNOW WHY OR WHAT CAUSED IT... THINGS DON'T JUST HAPPEN... CAUSE AND EFFECT.... AND VISE VERSA.
IN THIS CASE CHANGING THE REGULATOR, CKT BREAKER AND ALTERNATOR ALL ARE EXPENSIVE AND MAY NOT BE NECESSARY... THIS IS CALLED SHOTGUNNING. IF CHANGING THE REGULATOR FIXES THE PROBLEM CURRENTLY ONE GOES OFF FLYING THINKING THAT THEY ARE GOOD TO GO... BUT IN REALITY ITS THE ALTERNATOR DRIVE COUPLER (FOR INSTANCE) AND NOW THE ALTERNATOR FAILS IN FLIGHT... SENDING PARTS AND PIECES INTO THE CAM GEAR WHICH THEN TAKES OUT THE OIL PUMP GEAR SHAFT AS WELL AS RUPTURING THE ENGINE. ALL BECAUSE SOMEONE DIDN'T TAKE THE TIME TO FIND THE REAL PROBLEM... THEY THOUGHT IT WAS THE REGULATOR...THUS NOW OUR PILOT NOW .. IF HE MAKES IT BACK TO THE GROUND WITHOUT GOING THUD... HAS A BIGGER EXPENSE TO DEAL WITH... SHOTGUNNING IS A BAD WAY TO WORK ON AIRCRAFT. THAT IS WHY WE TRAIN MECHANICS TO THINK... AND FIND THE BAD PART CAUSING THE PROBLEM. SYMPTOMS ARE THE EFFECT THAT THE BAD PART CAUSES.
THEN AGAIN YOU ALREADY KNOW THIS TOO...
KEEP UP THE GOOD WORK.
fly safe GMAs
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