First off I'm not blaming anyone . Do not know the cause. Only looking for the cure as it has all parties stumped so I'm looking for ideas here.
Helping build a friends RV-14 with the EXP 119 engine. I know most will say a wiring issue , have at it but I have had enough people go through the wiring that I am personally ruling that one out unless people can tell me that Van's instructions will cause this scenario (don't think so).
Other than two thing which I will document , everything is connected as per Van's instructions.
(1) the #8 wire WH-P912 wire leaves the battery side of the starter relay (on the firewall) then goes up to the two shunts (jumped) then through the firewall to the main buss. The WH-P909 leaves the main alternator and goes to the shunt mentioned above as does the power from the standby alternator (second shunt) .
(2) Builder elected to install a 60 amp. switch mode power supply and it connects to the main buss via a CB. With the master off and you switch the power supply on , it powers up the avionics for ground testing and training. With the power supply on , 12V. can back track all the was forward to the battery side of the start relay (on the fuselage) then across the copper bar joining the start relay to the ship side of the master solenoid (but with the master off (as would be the case if your using the power supply) the power is not connecting to the battery). In case you have a battery charger on the battery and you want to play with the avionics.
Now as to what happened. On the initial panel power up with the ground power supply and no key in the ignition, we heard a click. It was the starter drive jumping forward. No turning just jumping forward every time power was applied (and clicking each time) . When power was removed the drive would back out. The start relay was not clicking. When you turn the key the start relay( on the firewall) has a loud click as it should. We tried to trouble shoot for quite a bit and all of a sudden it(the starter drive) stopped clicking and pushing the drive out. Strange it would stop after doing this many times. Jump forward a few days and we do the first engine start up and everything is working as it should. The next day (yesterday) we have the power supply on testing a few more things. Noise in the hangar ( I guess) as we did not hear the drive engage this time only to smell smoke. Smoke was coming out of the started. It was removed and sent to a engine builder and they disassembled it and as we expected it toasted the start solenoid on the starter.
With the starter removed , I cannot duplicate any scenario that applies power to the starter wires. We have been in contact with Van's , Lycoming and Hartzell . Other than you must have wires mixed up no one can explain our mystery. As Hartzell (Skytec) explained and I agree if the start relay wasn't forwarding power to the starter there wouldn't be power there to burn the starter up so it cannot be the starter's fault. The start relay had to be providing power some how or this would not have occurred. If the start relay was providing full power the starter would have turned.
Finally my question, can a faulty start relay (as mounted on the firewall) fail and pass power from the battery side without being commanded? I know they can stick on. Regardless , it's coming out and being replaced but it would be nice to know what took place. If the problem isn't the relay and it doesn't act up right away, I would hate to have this happen again let alone while in the air.
Thanks for reading such a long post, Ron
Helping build a friends RV-14 with the EXP 119 engine. I know most will say a wiring issue , have at it but I have had enough people go through the wiring that I am personally ruling that one out unless people can tell me that Van's instructions will cause this scenario (don't think so).
Other than two thing which I will document , everything is connected as per Van's instructions.
(1) the #8 wire WH-P912 wire leaves the battery side of the starter relay (on the firewall) then goes up to the two shunts (jumped) then through the firewall to the main buss. The WH-P909 leaves the main alternator and goes to the shunt mentioned above as does the power from the standby alternator (second shunt) .
(2) Builder elected to install a 60 amp. switch mode power supply and it connects to the main buss via a CB. With the master off and you switch the power supply on , it powers up the avionics for ground testing and training. With the power supply on , 12V. can back track all the was forward to the battery side of the start relay (on the fuselage) then across the copper bar joining the start relay to the ship side of the master solenoid (but with the master off (as would be the case if your using the power supply) the power is not connecting to the battery). In case you have a battery charger on the battery and you want to play with the avionics.
Now as to what happened. On the initial panel power up with the ground power supply and no key in the ignition, we heard a click. It was the starter drive jumping forward. No turning just jumping forward every time power was applied (and clicking each time) . When power was removed the drive would back out. The start relay was not clicking. When you turn the key the start relay( on the firewall) has a loud click as it should. We tried to trouble shoot for quite a bit and all of a sudden it(the starter drive) stopped clicking and pushing the drive out. Strange it would stop after doing this many times. Jump forward a few days and we do the first engine start up and everything is working as it should. The next day (yesterday) we have the power supply on testing a few more things. Noise in the hangar ( I guess) as we did not hear the drive engage this time only to smell smoke. Smoke was coming out of the started. It was removed and sent to a engine builder and they disassembled it and as we expected it toasted the start solenoid on the starter.
With the starter removed , I cannot duplicate any scenario that applies power to the starter wires. We have been in contact with Van's , Lycoming and Hartzell . Other than you must have wires mixed up no one can explain our mystery. As Hartzell (Skytec) explained and I agree if the start relay wasn't forwarding power to the starter there wouldn't be power there to burn the starter up so it cannot be the starter's fault. The start relay had to be providing power some how or this would not have occurred. If the start relay was providing full power the starter would have turned.
Finally my question, can a faulty start relay (as mounted on the firewall) fail and pass power from the battery side without being commanded? I know they can stick on. Regardless , it's coming out and being replaced but it would be nice to know what took place. If the problem isn't the relay and it doesn't act up right away, I would hate to have this happen again let alone while in the air.
Thanks for reading such a long post, Ron
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