JohnB

Replacement cowl flap and rudder/elevator trim indicators not available?

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Hi all,

 

My cowl flap indicator position light is out. On questioning my mechanic, he says the entire indicator has to be replaced and he says that Mooney is no longer making them? Ok its not such a big deal with a cowl flap indicator, but I heard the same is true for the elevator trim and rudder indicator lights as if those go out would be a bigger deal. Does anyone know if these are replaceable? I have now memorized the position from full deflection that is my takeoff trim and rudder trim position just in case those do go out, at least I will have that, but it would be nice to replace these when they fail. Anyone have a solution? Or is it wait until they fail and then best guess?

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John,

 

My cowl flap indicator is a bit flaky - sometimes indicating deployed when they're closed. So I'd like to know if there are replacements as well.

For your flap indicator, takeoff position reference is just about the same angle as full deflection of your ailerons.

 

Dave

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Are we sharing the same green LED bars for these. M, R and S?

Flaps, trim and rudder trim...

We had discussed sourcing them a while ago because the plastic film delaminates over time on many of them making them look a bit tired.

Good time to call and MSC to see if we can get the ball rolling between the factory and the supplier..?

Best regards,

-a-

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Aaron,

 

See the attached picture. This is from before I bough the airplane but the trim, flaps, cowl flaps and rudder trim are all illuminated.

I'd replace all of them if possible.

 

Dave

post-6965-0-74831200-1434954642_thumb.jp

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Ok that's about 5 of us so far that would want a solution for these indicators if they go out. (I can bet there's a number of us owners who's indicators have failed and are just dealing with it) I remember  someone here asked me how many revolutions up on the elevator trim wheel is the takeoff position on my indicator. 

 

I asked LASAR already, and they said the same, they're not being made, and the only ones they would have are ones scavenged from other Mooneys out of service :(. Doesn't seem that complicated of a part?

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John,

 

My cowl flap indicator is a bit flaky - sometimes indicating deployed when they're closed. So I'd like to know if there are replacements as well.

For your flap indicator, takeoff position reference is just about the same angle as full deflection of your ailerons.

 

Dave

Thanks Dave,

 

 Good point! I could probably deal with my flap indicator light being out if that failed, as you can see them as you mentioned. But for the things like cowl flaps, elevator trim and rudder trim positions, which you can't see while flying. that would be non optimal, and yes i'd pay to get those done if i could!

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I had a look at the schematic for my Ovation and extracted the page with the indicators on it.  Looks as if the Rudder Trim Indicator is one item while the elevator trim and flap position indicators are both in one sub-assembly.   I also found the Rudder Trim Potentiometer.  

It appears that the three wires from the Rudder Trim Potentiometer are routed to the Rudder Trim Indicator.  The Rudder Trim Indicator reads the analog voltage at the wiper of the Rudder Trim Potentiometer which corresponds to the Rudder position.   Then the Rudder Trim Indicator makes an analog to digital conversion and displays the closest value on an (approximately) 14 bar graph.   Other inputs to the Rudder Trim Indicator must be ground, power.  Panel dimmer might also be an input.  That still leaves at least two wires to the Rudder Trim Indicator unaccounted for. (Meaning I have not tracked them down through the spaghetti maze on the diagrams)

If the bars on the Rudder Trim Indicator are not working at all, or if some but not all of the digits appear, there could be a problem at either the Rudder Trim Indicator or the Rudder Trim Potentiometer.    IF the wiper of the latter is intermittent then the value is 'missing' and no bar might be illuminated as the ADC is out of range.  OR, if one or more of the LED bar elements has failed in the Rudder Trim Indicator then that could account for the missing positions.  

If you locate the Rudder Trim Potentiometer you could read the voltage at the wiper while someone runs the Rudder Trim through its limits.   If the voltage read at the wiper changes smoothly on the meter throughout the trim range then I'd say the potentiometer is OK. 

As for a failure on the display end of the system -- it seems possible that the LED bar graphs were contaminated during assembly of the DIP LED module and that individual segments fail.  It should be possible to find a replacement display module.   I doubt the ADC is failed, though if there is an output for each display segment one or more of those drivers could have blown.  That's probably in a single IC.  Probably one can find a replacement for the semiconductor or some new old stock.

The easiest way to get this fixed is to get Mooney to build a replacement.   If that's not possible then an owner produced part ought to be kosher. 

So far all my 2000 M20R's displays are ok....

If anyone has a defective unit to send me I'll take it apart and report back about repairing these indicators.

 

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The indicator is similar to our Mooney rudder trim display. However it is designed to read the potentiometer in the RAC servo, which is probably not the same resistance, and is a 12 volt system not the 24 volt type we need. Also not an approved part, of course.

 

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Ok that's about 5 of us so far that would want a solution for these indicators if they go out. (I can bet there's a number of us owners who's indicators have failed and are just dealing with it) I remember  someone here asked me how many revolutions up on the elevator trim wheel is the takeoff position on my indicator. 

 

I asked LASAR already, and they said the same, they're not being made, and the only ones they would have are ones scavenged from other Mooneys out of service :(. Doesn't seem that complicated of a part?

I just found a replacement unit for my Eagle on Mooney's web-site.  My indicator is  PN 800391-505 and a replacement kit is available (PN 940152-509).  Does anyone know what the differences are?  

It should be the same for M20R and perhaps M20M?

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I had a look at the schematic for my Ovation and extracted the page with the indicators on it.  Looks as if the Rudder Trim Indicator is one item while the elevator trim and flap position indicators are both in one sub-assembly.   I also found the Rudder Trim Potentiometer.  

It appears that the three wires from the Rudder Trim Potentiometer are routed to the Rudder Trim Indicator.  The Rudder Trim Indicator reads the analog voltage at the wiper of the Rudder Trim Potentiometer which corresponds to the Rudder position.   Then the Rudder Trim Indicator makes an analog to digital conversion and displays the closest value on an (approximately) 14 bar graph.   Other inputs to the Rudder Trim Indicator must be ground, power.  Panel dimmer might also be an input.  That still leaves at least two wires to the Rudder Trim Indicator unaccounted for. (Meaning I have not tracked them down through the spaghetti maze on the diagrams)

If the bars on the Rudder Trim Indicator are not working at all, or if some but not all of the digits appear, there could be a problem at either the Rudder Trim Indicator or the Rudder Trim Potentiometer.    IF the wiper of the latter is intermittent then the value is 'missing' and no bar might be illuminated as the ADC is out of range.  OR, if one or more of the LED bar elements has failed in the Rudder Trim Indicator then that could account for the missing positions.  

If you locate the Rudder Trim Potentiometer you could read the voltage at the wiper while someone runs the Rudder Trim through its limits.   If the voltage read at the wiper changes smoothly on the meter throughout the trim range then I'd say the potentiometer is OK. 

As for a failure on the display end of the system -- it seems possible that the LED bar graphs were contaminated during assembly of the DIP LED module and that individual segments fail.  It should be possible to find a replacement display module.   I doubt the ADC is failed, though if there is an output for each display segment one or more of those drivers could have blown.  That's probably in a single IC.  Probably one can find a replacement for the semiconductor or some new old stock.

The easiest way to get this fixed is to get Mooney to build a replacement.   If that's not possible then an owner produced part ought to be kosher. 

So far all my 2000 M20R's displays are ok....

If anyone has a defective unit to send me I'll take it apart and report back about repairing these indicators.

 

Jerry,

great point, I told LASAR about my flap indicator, they took it apart and found out that a resistor was bad, replaced it, now it works like a charm! So these things are fixable!

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Mooney sells the face plate (~$60) and LEDs (~$3.00) for the trim and flap indicator unit.  I just replaced the face plate on mine.  

I also bought a few LEDs since they are obsolete and may be hard to find if I need them in a few years.  

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On 11/5/2015 at 9:10 PM, JohnB said:

Jerry,

great point, I told LASAR about my flap indicator, they took it apart and found out that a resistor was bad, replaced it, now it works like a charm! So these things are fixable!

Problem solved!!

With the help of John B, I called and got ahold of Lonnie in the Avionics shop at LASAR. He said that there is a Pico Fuse (1/4 amp)  that goes bad on these circuits and needs to be replaced. It is wired into the circuit board. They send them out to an electronics shop to be repaired.

I ordered 10 pico fuses from Mouser and had a radio shop replace one in 10 minutes and the problem is solved on my trim indicator. It is the same fuse that goes bad on the Trim, Flaps, Cowl Flaps and Rudder Trim indicators on the later K & J, TLS, Bravo, Ovation and Eagle.

 

This is the green 1/4 amp Pico fuse that goes bad:

 

IMG_7088.JPG

Edited by LANCECASPER
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On 12/19/2015 at 4:23 PM, LANCECASPER said:

Problem solved!!

With the help of John B, I called and got ahold of Lonnie in the Avionics shop at LASAR. He said that there is a Pico Fuse (1/4 amp)  that goes bad on these circuits and needs to be replaced. It is wired into the circuit board. They send them out to an electronics shop to be repaired.

I ordered 10 pico fuses from Mouser and had a radio shop replace one in 10 minutes and the problem is solved on my trim indicator. It is the same fuse that goes bad on the Trim, Flaps and Rudder Trim indicators on the TLS, Bravo, Ovation and Eagle.

 

This is the green 1/4 amp Pico fuse that goes bad:

 

IMG_7088.JPG

Nice!!! Im glad it worked out.. and thanks for the pictures.. Now I know what it looked like. Whew.. nice to know there's solutions out there for fixing our birds!

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Does anyone have the part number for the light bulbs in the Moritz gauges?  There are two types there but the one with hight brightness does not last long.

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THANK YOU LANCECASPER!

My rudder trim display has been dark since I purchased the plane 20 months ago. I just saw this post a few days ago, and showed it to my hanger elf. He confirmed the fuse was failed, replaced it, and the indicator now works for the first time in forever. 

While the unit was out I traced out the logic and created a schematic. The main chip inside is the LM3914, and it is available. The rest of the parts are generic. So the device should be maintainable at the component level. 

The flap and elevator trim are similar, but they use 2 cascaded LM3914 chips to drive 20 led's. I did not trace out the circuit, but it should be substantially similar.

There is little the fuse protects, I see little need for it. The first thing the power lead hits (after the fuse) are two voltage regulators which both have short circuit protection. In my unit, the fuse was a small 1/8 A. I think it should be larger, like 1/2 A. 

Larry

rudder_trim_indicator_schematic.pdf

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On 1/7/2019 at 8:07 PM, larryb said:

THANK YOU LANCECASPER!

My rudder trim display has been dark since I purchased the plane 20 months ago. I just saw this post a few days ago, and showed it to my hanger elf. He confirmed the fuse was failed, replaced it, and the indicator now works for the first time in forever. 

While the unit was out I traced out the logic and created a schematic. The main chip inside is the LM3914, and it is available. The rest of the parts are generic. So the device should be maintainable at the component level. 

The flap and elevator trim are similar, but they use 2 cascaded LM3914 chips to drive 20 led's. I did not trace out the circuit, but it should be substantially similar.

There is little the fuse protects, I see little need for it. The first thing the power lead hits (after the fuse) are two voltage regulators which both have short circuit protection. In my unit, the fuse was a small 1/8 A. I think it should be larger, like 1/2 A. 

Larry

rudder_trim_indicator_schematic.pdf

Excellent..hangar elf that can produce schematics,!

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