Trim/Flap Indicator issue - M-20M

[IvanP]

Loking for some collective wisdom about Trim/Flap indicator malfunction on 1990 Bravo. Couple of flights ago, the flap indicator started to flicker a bit and then no LED bars were on for teh rest of the flight. Trim indicator remained fully functional. The next day, the flap indicator LED bar in UP position was on but no other segments woud light up when the flaps were moved. The LED bar indicating UP position now remains on, regardless of actual position of flaps. Trim indicator is fine.

I found a thread here about the potentiometer being possibly the culprit and changed the pot. This did not help. I checked the new pot before installing it and it was good. I am still geting the UP inidcation regardless of where the flaps are. Any ideas on what could be causing this?

Thank you in advance for any thoughts and ideas.

 

[LANCECASPER]

 

 

16 hours ago, IvanP said:

Loking for some collective wisdom about Trim/Flap indicator malfunction on 1990 Bravo. Couple of flights ago, the flap indicator started to flicker a bit and then no LED bars were on for teh rest of the flight. Trim indicator remained fully functional. The next day, the flap indicator LED bar in UP position was on but no other segments woud light up when the flaps were moved. The LED bar indicating UP position now remains on, regardless of actual position of flaps. Trim indicator is fine.

I found a thread here about the potentiometer being possibly the culprit and changed the pot. This did not help. I checked the new pot before installing it and it was good. I am still geting the UP inidcation regardless of where the flaps are. Any ideas on what could be causing this?

Thank you in advance for any thoughts and ideas.

 

It turned out to be the pico fuse in the trip/flap indicator "box" in my Bravo - that solved it.

[IvanP]

I was thinking about the fuse as well. If it was the fuse, I woudl expect the indicator to be completely dark. Mine shows light in the up position when teh master is on. Is there more than one fuse in this magic box? 

[LANCECASPER]

2 hours ago, IvanP said:

I was thinking about the fuse as well. If it was the fuse, I woudl expect the indicator to be completely dark. Mine shows light in the up position when teh master is on. Is there more than one fuse in this magic box? 

It’s a small fuse in the box - the lights will still flicker and sometimes stay in the wrong spot when the pico fuse goes bad.

[IvanP]

44 minutes ago, LANCECASPER said:

It’s a small fuse in the box - the lights will still flicker and sometimes stay in the wrong spot when the pico fuse goes bad.

I see. Will have to yank the box out and look inside. Looks like it is not going to be easy to get to. Do you, by chance, recall the fuse specs and sourcing?

Thanks for yoru advice. 

[LANCECASPER]

6 hours ago, IvanP said:

I see. Will have to yank the box out and look inside. Looks like it is not going to be easy to get to. Do you, by chance, recall the fuse specs and sourcing?

Thanks for yoru advice. 

If you go back and read the post I quoted it should be there.

[IvanP]

Update on the Trim/Flap Indicator box - after today's flight both trim and flap indicators show UP position, regardless of actual position of trim or flaps. Trim indicator was OK on take-off, but after about 1 hour it went dark. After shutdown, I turned the master on again and the LEDs in up position on both are on, but no movement. 

Definitely will have to take the box out and get it fixed, but I have a trip scheduled later this week. I can eyeball T/O flaps without problems, but the trim is a different story. Does anyone have experience with setting the trim for T/O without the indicator on a long body?  Thanks in advance for any advice.

[Slick Nick]

That's a tricky one, trim is one of those "killer items". Wouldn't want to just be guessing where it's set.

And unlike a traditional trim tab, it's not exactly something that can be done by eye from the outside of the aircraft. 

[N201MKTurbo]

Turn the trim wheel all the way nose down. Run it all the way nose up and count the revolutions of the trim wheel. Put some tape on it to make it easier to count. Put it half way between the two and you will have safe trim for takeoff. If it seems to nose or tail heavy on takeoff, adjust your count as necessary.