Flap Relays

[Releew]

A while ago, I published that my flaps would deploy and would not retract.  After some extensive troubleshooting, it was linked to two sealed relays.  Each micro switch in the circuit was methodically checked and found OK.  The relays are hard soldered to a circuit board.  Mouser electronics helped cross match the relays from the currently installed part.  I looked in my service manual, but could not find any information on the relays.  The new relays were installed and worked flawlessly until last week.  Same problem occurred!  I never found a "Smoking Gun" on the first replacement, so although the problem was solved, I could not conclude how these relays got their contacts fired.  We use hundreds of relays in control panels at work and I have very seldom had relay failures.  So why?  It turns out the Flap Target was too close the the contact wheel of the micro switches.  With the aircraft on the ground, and flaps at takeoff position (and Gravity doing its thing) the separation of the target and the switch contact was enough to drop the circuit.   BUT...... when the flap were generating lift, it moved the target fractions closer to the switch contact and created relay chatter.  Ill admit, this was discovered by accident when a friend in the hangar happen to lift up on the flap when I was staring up at the flap motor.  Sure enough, the relays started humming and the motor started pulsing.  Its a wonder they lasted as long as they did!!!

Just wanted to pass this along.  This site should be all about passing on information to solve problems!

 

Rick

[larryb]

I found the same thing while troubleshooting my flap relay problem last year. I was able to get the system to chatter on the ground when I put upward pressure on the flap while it was in the take off position. My solution was to widen the "dead zone" where both relays are activated and the flaps are in the TO position. We did this by grinding away a little material on the lower section of the lever that activates the rollers of the microswitches. I also found poor alignment of the microswitch. The switches were adjusted too close to the lever such that one of the rollers had bent. 

[Mooney_Allegro]

Hello Releew,

Your post was perfect timing.  My original Wing Flap Relay Assembly failed last October, at 500 hours TT, costing about $1800 just for that board in the photograph below, not including labor.   Last Friday, 46 hours since the last failure, and 5 months later, the same thing happened.  I landed, retracted the flaps, and the Flap CB popped, and couldn't retract the flaps.  They stuck at full flaps.  I believe the problem is the Relay Assembly, just like before.  I spoke to Mooney about it, and they said they've been having issues where these boards have been failing on an increasing basis.  One of Premier Aircraft's demo new Mooneys had the same failure last October.  The local MSC will look at my plane tomorrow and I'll know more information on the cause, but I suspect it to be the Flap Relay Assembly again.   I'll pass along your info to my technician tomorrow.   

The photos below are the failed assembly from last October.   It almost looks like there's thermal damage to the 1st photo.  The card that's in my plane now is another brand, from the Javelina Corporation.  Mooney advised me that they're using a new provider.  If my new card is in fact bad, that means that it only lasted 5 months and 46 hours.  I'll advise tomorrow what they find.

Thx

[carusoam]

Great details gents!

This problem seems to surface at least once each year....

But, this is the first time i’ve Heard about the test for chatter...

https://mooneyspace.com/search/?q=Flap relay switch&updated_after=any&sortby=relevancy&search_and_or=and

I think Lance May have written about relay part numbers... (fuzzy memory on my part...)

The chatter test may explain why the relays don’t work so well on the ground, but may work better when there is a load on the flaps while flying...

hmmmm.....?

PP thoughts only, not a mechanic...

Best regards,

-a-

[larryb]

These are all standard relays. The boards can be repaired at the component level for just a few $.

[Releew]

Correct.....  The Potter Brumfield relays were $11.00 each.  You need to know how to remove and replace as they are soldered in position.  No Biggie.....

I was just happy to find a Root Cause.....  Mine chattered under a load, meaning when "in air."

 

Rick

[Yetti]

Top relay in the pic has heat damage.   Look for the relay number on Digi Key.   Should take about 6 minutes to replace for someone who has soldering experience.  And a decent soldering station.

[Yetti]

ebay for the win

https://www.ebay.com/i/202619389822?chn=ps

[Mooney_Allegro]

I have some more info on my flaps stuck at full flaps.  The mechanic working on my plane discovered that the flaps started working again after disconnecting, cleaning, & blowing out the terminals with high pressure air, then using contact cleaner on the electrical connections.  The flaps were cycled a dozen times with no issues.  I originally thought the problem was with the Wing Flap Relay Assembly, but I was wrong.   

[Mooney_Allegro]

This is the new style board Mooney is using.  Are these "relays" easy to change out just like the older style pictured in a few threads above?  I'm told by a MSC that this board cost almost $1800 to replace (entire assembly), not including labor.  

[larryb]

Those relays appear to be soldered to the board. Replacing individual relays is not hard if you know what you are doing but they are not plug-in either.

[Yetti]

I'm still wondering why you need 18 wires going to a flap relay board.    Oh and yes contact cleaner on flap limit switches is SOP.   Also gently wiggling the flaps will sometimes make the flaps start working again.

[Releew]

Agree.....  electrically this can be done with Four Switches and no relays.  Without a schematic its hard to tell what they are utilize for, but if I had to guess, its to latch and provide a permissive path to the secondary relay or other switch in the circuit.

[larryb]

When I was troubleshooting my flap relay problem last year I created this diagram from the Mooney wiring diagram and measurements of my circuit. 

 

[carusoam]

Nice logic, Larry!

Thanks for Sharing that.

Best regards,

-a-

[rgpilot]

I had a problem with flaps stuck in the up position on 2004 Ovation. I removed belly pan and tapped on relay and the flaps immediately began working.

I purchased a replacement relay as described by "Yetti" a Omron G8P-1C4P 24VDC which looks just like the relay I was trying to replace but I found that the Omron relay has five pins  and the original relay had 6 pins. Alfter spending hours looking for an exact replacement for the original, I could not find any. How does the five pin relay replace the six pin relay?

Is there a pin that is not needed?

[larryb]

The 6 pin relay has two pins that are tied together inside. I think it is the common contact pin. In my board it had to be jumpered with a piece of wire because the board used the pin that was not present in the 5 pin version. If you find the data sheet on both the old and new relays it will be clear.

[rgpilot]

That's what I thought, but I don't have any data sheets and I and not sure which pins to jump on the board. Maybe I can check the old relay with an omn meter and figure it out.

[larryb]

The JT1E-DC24V relay has 2 common contact pins, one near the coil and one near the NO and NC contacts.
The alternate relay does not have the common contact pin near the coil pins.
The Mooney circuit board does not have a trace feeding the common contact pin of the alternate relay.
Therefore, a jumper is needed on the board from the common contact pin near the coil pins to the other common contact.

Note that most pcb power relays have the same footprint. Mostly interchangable.

 

[rgpilot]

That's helpful but I am still not sure where to put the jumper.

[larryb]

It just so happens that I have had another issue with my relays and had an opportunity to take a picture with the jumper in place. This is the jumper required when replacing the factory 6 pin relay with the alternate 5 pin relays that are available today.

 

 

[Daneshgari]

Hi all. i just had my second relay replaced by MSC at Lapeer, MI. my great mechanic Jay believes that the TKS fluid maybe one of the contributors to the failure. Has anyone found a correlation there?

Perry

[N201MKTurbo]

12 minutes ago, Daneshgari said:

Hi all. i just had my second relay replaced by MSC at Lapeer, MI. my great mechanic Jay believes that the TKS fluid maybe one of the contributors to the failure. Has anyone found a correlation there?

Perry

What was wrong with the relay? Burned contacts? Welded contacts? Melted plastic? Open coil? 

Did you take it apart to find the root cause?

[Daneshgari]

The flaps would not retract. The mechanic believed that the relays were fried.

[N201MKTurbo]

Ok, so we don’t know the failure mode of the relay. 

TKS fluid is essentially antifreeze and alcohol. (Ethylene glycol, diethylene glycol and isopropyl alcohol) 

None of those are very conductive or corrosive to the circuit board parts. The IPA May soften the plastic if left on it long enough, but you would see that by visual inspection. It’s possible that the relay became filled with TKS fluid and the IPA would have time to soften the plastic parts, but that seems unlikely considering where it is located. It seems like at most it may get slight incidental contact with the fluid being blown up through the skin joints in the belly. It seems like it would evaporate before it had time to do any damage.