File this under strange but true. (Follow up to PSA bulb)

[Guitarmaster]

The title say it all.  Strange but true.  

As a follow-up to the installation of the PSA Paddle bulbs, I have this to report...

For reasons unbeknownst to me, the nav light circuit must have a resistive load in order for the "GEAR DN" light to work.  Here where it gets even weirder;  this occurs while the nav lights are OFF!  I re-installed the incandescent lights and voila!  "GEAR DN" illuminates.  

I decided to do some experimentation.  With one incandescent nav installed, everything worked normal.  Both installed, of course it worked.  With both removed, no "GEAR DN" light.  

My conclusion is this.  Mooney runs the nav light circuit through the gear circuit somehow.  Probably for the dimming feature.  For the indication system (it doesn't affect the "GEAR UNSAFE" at all) to work at all, it relies on a resistive load through the nav lights.  Maybe Clarence can shed some light??

So, after all that, and the long "discussion' from the other thread, I'm back to the incandescents.   Now to see if Spruce will take them back...  after that, a call to PSA to let them know of this issue.


 

Edited January 8, 2016 by Guitarmaster

[Marauder]

The title say it all.  Strange but true.  

As a follow-up to the installation of the PSA Paddle bulbs, I have this to report...

For reasons unbeknownst to me, the nav light circuit must have a resistive load in order for the "GEAR DN" light to work.  Here where it gets even weirder;  this occurs while the nav lights are OFF!  I re-installed the incandescent lights and voila!  "GEAR DN" illuminates.  

I decided to do some experimentation.  With one incandescent nav installed, everything worked normal.  Both installed, of course it worked.  With both removed, no "GEAR DN" light.  

My conclusion is this.  Mooney runs the nav light circuit through the gear circuit somehow.  Probably for the dimming feature.  For the indication system (it doesn't affect the "GEAR UNSAFE" at all) to work at all, it relies on a resistive load through the nav lights.  Maybe Clarence can shed some light??

So, after all that, and the long "discussion' from the other thread, I'm back to the incandescents.   Now to see if Spruce will take them back...  after that, a call to PSA to let them know of this issue.

 

That is exactly what is going on. In your 1975 F, when you turn on the Nav lights, it dims the gear position indicators.

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[Guitarmaster]

Here's the scoop straight from Willmar.

The Pre-J Mooney's with the electric gear have to have a resistive load installed in the nav light circuit.  It is part of the dimmer logic Mooney used in the day. The gear indication will not work otherwise.  Understand, this is with the nav lights off.   IN ADDITION, because of the way the circuit works, it can affect the operation of the gear itself!   This explains the flight home the other night in which the gear would not retract all the way.  That was a slow flight at 115 MPH.

IMPORTANT!!  If the nav lights are not working (no resistance in the circuit), there is a good chance you will have gear problems.  I love my airplane, but what a crap design.

I called Bob at PSA and told him about it.  He said they would see if there was a way to design the bulb to work with those systems.  

The bulbs are great!!!  I just can't use them.

On a side note, for those without electric gear, I happen to have two paddle bulbs with the clear lenses for sale.
 

Edited January 8, 2016 by Guitarmaster

[Yetti]

Same issue with can bus and swapping to LED.   Say LED flashers on a motorcycle.   You will still get a indicator out after installing the LED.    Most people will add a resistor to the circuit.   For some reason 330 ohms rings a bell. Ohm out one light and that would be close.

 

[carusoam]

Things I have learned from MS...

 

Question: How do the 'approved' LED Nav lights handle the same situation?

Observations:

1) That illustrates how a simple bulb change in a certified plane may not be so simple.

2) Add this to other LED lights used to light the panel.  The dimmer doesn't work unless at least one incandescent bulb stays in the circuit. Becomes obvious on the first night flight.

3) In the news this week, the low fuel light in the anunciator panel may not be enabled unless this panel has it's test button pressed and held prior to it working.  It is in my checklist.  But, didn't know how critical this simple step is to the system's function.

4) As designed, the gear down light in the annunciator panel is hard to see in daylight with the Nav lights on.

5) Leaving the Nav lights on during the day, in fact, makes missing one of the more obvious warnings of the gear being left up more easy to miss.

6) There still isn't an improvement available for the limit switches in the landing gear system. (Unrelated to this thread, I think...)

The progression of the digital age makes the analog age of consumer products look quite ancient.

After recently seeing a linear actuator being used to automatically control the mixture, I can see digital updates properly creeping in for our aging fleet.

Best regards,

-a-

 

[Guitarmaster]

 

Same issue with can bus and swapping to LED.   Say LED flashers on a motorcycle.   You will still get a indicator out after installing the LED.    Most people will add a resistor to the circuit.   For some reason 330 ohms rings a bell. Ohm out one light and that would be close.

 

I thought of adding a resistor, but of course, the airplane is certified so....

If you ohm out the nav system, it is roughly 5.6 ohms per bulb.  Only one in the circuit seems to solve the problem so it doesn't take much. 

[HRM]

Not weird at all.

Locate schematic.

Take this course.

Problem solved.

Hint: the fun part about LEDs is that they are not resistors

[Guitarmaster]

 

Question: How do the 'approved' LED Nav lights handle the same situation?

It's a good question.  I would bet there is some resistance built into the unit.

[carusoam]

Harley you are hot today!

Could it be as easy as present the new challenge and the schematic to your mechanic.  Have him select a proper, new post to connect the wire to, thus restoring the proper operation of the gear?

Best regards,

-a-

[Marauder]

Here's the scoop straight from Willmar.

The Pre-J Mooney's with the electric gear have to have a resistive load installed in the nav light circuit.  It is part of the dimmer logic Mooney used in the day. The gear indication will not work otherwise.  Understand, this is with the nav lights off.   IN ADDITION, because of the way the circuit works, it can affect the operation of the gear itself!   This explains the flight home the other night in which the gear would not retract all the way.  That was a slow flight at 115 MPH.

IMPORTANT!!  If the nav lights are not working (no resistance in the circuit), there is a good chance you will have gear problems.  I love my airplane, but what a crap design.

I called Bob at PSA and told him about it.  He said they would see if there was a way to design the bulb to work with those systems.  

The bulbs are great!!!  I just can't use them.

On a side note, for those without electric gear, I happen to have two paddle bulbs with the clear lenses for sale.

 

Matt -- I'm having a hard time following you on this. I know there is a connection between the gear condition lights and the Nav lights. When you have the Nav lights on, they dim the condition lights.

What you wrote indicates that if you have a problem in the Nav light circuitry, you may not be able to use the gear. Did I read that right?

I spent weeks troublingshooting my gear breaker popping issue back in the 90s and don't recall any actual relationship between the gear motor mechanism and the condition lighting condition. Can you explain more?

Also, you indicated you had a gear issue that it wouldn't retract all the way. Did you get the "gear unsafe" warning and no movement of the gear (as indicated by the floor indicator) or did it partially retract and then stopped?

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[Marauder]

Also, does your plane have the override switch?

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[Guitarmaster]

OK.  Got it figured out!  It took some more in-depth study of the schematics, but here goes...

It's not a resistive load thing like I (and Wilmar) thought it was.  It's a ground lift problem.

Here goes....  when the nav lights are off, the "gear down" light grounds through the nav lights.  It does't matter which one.  As long as one bulb is good, there will be a ground and it works just fine.  When the nav lights are on, the normal ground, nav lights, is lifted and so the current must find a different path.  That path is through the "dimming resistor" to a different ground.  With all my grumping about crap design, it is pretty ingenious especially for the 60's.  The system works flawlessly... as long as the filaments in one of the three bulbs is intact.  

Since LED's have no filament, there is no "hard" connection between + and - essentially lifting the ground.  This could easily be solved by jumping the terminals at the bulb with a small resistor.  

"Also, you indicated you had a gear issue that it wouldn't retract all the way. Did you get the "gear unsafe" warning and no movement of the gear (as indicated by the floor indicator) or did it partially retract and then stopped?"

Yes, I thought the two might be related, but I think it is just coincidence.  I came up partially and stopped.  It was cold out so in retrospect, the squat switch may be the culprit here.  I am thinking a bypass switch will be installed at annual.  Probably new biscuits are in order as well.  Gear shift....
The guy at Wilmar said the down limit switches in these airplanes are a problem and they replace MANY in airplanes displaying the same symptoms as mine.  I am sure that is the problem with no gear in the freezing temps.

The plane has been more of a project than I wanted, but it has been fun!  

[carusoam]

cold 'old' donuts and squat switches are the reason for the by pass switch.

Many threads on that topic.

squat switches evolved into airspeed switches.

other things to consider if you are adding a bypass.

airspeed switches are also being used for some modern Nav equipment, ADSB?

Best regards,

-a-

 

[HRM]

 

It's not a resistive load thing like I (and Wilmar) thought it was.  It's a ground lift problem.

Here goes....  when the nav lights are off, the "gear down" light grounds through the nav lights.  It does't matter which one.  As long as one bulb is good, there will be a ground and it works just fine.  When the nav lights are on, the normal ground, nav lights, is lifted and so the current must find a different path.  That path is through the "dimming resistor" to a different ground.  With all my grumping about crap design, it is pretty ingenious especially for the 60's.  The system works flawlessly... as long as the filaments in one of the three bulbs is intact.  

Since LED's have no filament, there is no "hard" connection between + and - essentially lifting the ground.  This could easily be solved by jumping the terminals at the bulb with a small resistor.  

...and I'll bet you didn't even take the EDx course like I suggested.

The LED is a diode, the 'D' in LED. Back in the 60's, no one would have imagined an LED capable of replacing a filament bulb in this application.

After earlier discussion in the prior thread one must consider mods that might affect critical systems. Recall "Butterfly Effect" and "Rule and Context Regression"?

{critical systems : landing gear}

[Guitarmaster]

 

...and I'll bet you didn't even take the EDx course like I suggested.

The LED is a diode, the 'D' in LED. Back in the 60's, no one would have imagined an LED capable of replacing a filament bulb in this application.

After earlier discussion in the prior thread one must consider mods that might affect critical systems. Recall "Butterfly Effect" and "Rule and Context Regression"?

{critical systems : landing gear}

OK.  Yep.  You got me.  

Alright... yes, i know what an LED is and how its works.  I guess I used the wrong terminology.  Sorry.  Im a pilot. not an engineer.

So, technically NOT an open circuit, but it might as well be in terms of how the system sees it.  

and, yes, I did sign up for the course.  It looks interesting and I always like to expand my knowledge.

Edited January 8, 2016 by Guitarmaster

[Guitarmaster]

 

cold 'old' donuts and squat switches are the reason for the by pass switch.

Many threads on that topic.

squat switches evolved into airspeed switches.

other things to consider if you are adding a bypass.

airspeed switches are also being used for some modern Nav equipment, ADSB?

Best regards,

-a-

 

I will check that out.  "Modern" would not be the adjective of choice to describe my panel.

[ryoder]

 

Here's the scoop straight from Willmar.

The Pre-J Mooney's with the electric gear have to have a resistive load installed in the nav light circuit.  It is part of the dimmer logic Mooney used in the day. The gear indication will not work otherwise.  Understand, this is with the nav lights off.   IN ADDITION, because of the way the circuit works, it can affect the operation of the gear itself!   This explains the flight home the other night in which the gear would not retract all the way.  That was a slow flight at 115 MPH.

IMPORTANT!!  If the nav lights are not working (no resistance in the circuit), there is a good chance you will have gear problems.  I love my airplane, but what a crap design.

I called Bob at PSA and told him about it.  He said they would see if there was a way to design the bulb to work with those systems.  

The bulbs are great!!!  I just can't use them.

On a side note, for those without electric gear, I happen to have two paddle bulbs with the clear lenses for sale.
 

Wow.  What a failure mode.  Glad I have the manual gear even if it has its own drawbacks.

[Guitarmaster]

  Here's the scoop straight from Willmar.

The Pre-J Mooney's with the electric gear have to have a resistive load installed in the nav light circuit.  It is part of the dimmer logic Mooney used in the day. The gear indication will not work otherwise.  Understand, this is with the nav lights off.   IN ADDITION, because of the way the circuit works, it can affect the operation of the gear itself!   This explains the flight home the other night in which the gear would not retract all the way.  That was a slow flight at 115 MPH.

IMPORTANT!!  If the nav lights are not working (no resistance in the circuit), there is a good chance you will have gear problems.  I love my airplane, but what a crap design.

I called Bob at PSA and told him about it.  He said they would see if there was a way to design the bulb to work with those systems.  

The bulbs are great!!!  I just can't use them.

On a side note, for those without electric gear, I happen to have two paddle bulbs with the clear lenses for sale.

 

Wow.  What a failure mode.  Glad I have the manual gear even if it has its own drawbacks.

I was incorrect on this. It just affects the indication.

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[ryoder]

 

I was incorrect on this. It just affects the indication.

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Ok good.  That would be terrible.

[Marauder]

  I was incorrect on this. It just affects the indication.

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Ok good.  That would be terrible.

And scary!

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[Marauder]

OK.  Got it figured out!  It took some more in-depth study of the schematics, but here goes...

It's not a resistive load thing like I (and Wilmar) thought it was.  It's a ground lift problem.

Here goes....  when the nav lights are off, the "gear down" light grounds through the nav lights.  It does't matter which one.  As long as one bulb is good, there will be a ground and it works just fine.  When the nav lights are on, the normal ground, nav lights, is lifted and so the current must find a different path.  That path is through the "dimming resistor" to a different ground.  With all my grumping about crap design, it is pretty ingenious especially for the 60's.  The system works flawlessly... as long as the filaments in one of the three bulbs is intact.  

Since LED's have no filament, there is no "hard" connection between + and - essentially lifting the ground.  This could easily be solved by jumping the terminals at the bulb with a small resistor.  

"Also, you indicated you had a gear issue that it wouldn't retract all the way. Did you get the "gear unsafe" warning and no movement of the gear (as indicated by the floor indicator) or did it partially retract and then stopped?"

Yes, I thought the two might be related, but I think it is just coincidence.  I came up partially and stopped.  It was cold out so in retrospect, the squat switch may be the culprit here.  I am thinking a bypass switch will be installed at annual.  Probably new biscuits are in order as well.  Gear shift....

The guy at Wilmar said the down limit switches in these airplanes are a problem and they replace MANY in airplanes displaying the same symptoms as mine.  I am sure that is the problem with no gear in the freezing temps.

The plane has been more of a project than I wanted, but it has been fun!  

Thanks for the follow up. The reason I asked is that I would get the "gear unsafe" light as I went to retract the gear. The donuts didn't expand enough to make contact with the squat switch on colder days (something that happens a lot in Buffalo). This would always be just as I went to retract the gear. It never happened mid cycle. If it does, then I think a limit switch is more likely the culprit.

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[HRM]

 

OK.  Yep.  You got me.  

Alright... yes, i know what an LED is and how its works.  I guess I used the wrong terminology.  Sorry.  Im a pilot. not an engineer.

So, technically NOT an open circuit, but it might as well be in terms of how the system sees it.  

and, yes, I did sign up for the course.  It looks interesting and I always like to expand my knowledge.

Frankly, you did good (I am an engineer and a pilot) and you illuminated, no pun intended, a very interesting issue that many will profit from.

I was just being tongue-in-cheek about the course, but my smart-aleck (the apple doesn't fall far from the tree, no?) molecular biologist son took it and declared himself an EE--so enjoy!

[StinkBug]

 

On a side note, for those without electric gear, I happen to have two paddle bulbs with the clear lenses for sale.
 

I have manual gear and would be interested.