jcovington

Daytona Gear Incident

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7 hours ago, David Herman said:

Interestingly enough ... I had this similar situation in a Piper Arrow (PA-28) in the early 1990s when we put the gear down before landing in Tallahassee (KTLH). No lights. Three dark un-illuminated gear lights. It was a rental and the FBO Owner had just finished “checking me out” in the plane so I could rent it. (I remember being disappointed and thinking to myself, “I guess the checkout isn’t over yet”) We aborted the approach, talked to tower and exited the pattern. The gear was down, we thought, we felt it come down, but there were no green lights ... all three lights were out. Hmmm ... We performed the emergency extension procedures, returned for a a low approach, asked tower what they saw? Tower said, “They looked down,” to which we asked “all three?” He said ... “ all three look down, from what I can see, but I can’t guarantee anything.” We went back around the pattern and landed. Uneventfully.

After touchdown, I remember holding back pressure and keeping the nose wheel up until there wasn’t enough wind over the elevators to hold it up. We had discussed this prior ... just in case the nosewheel wasn’t locked. We discussed it ... but I can’t remember if we decided to pull the mixture and cutoff the engine at that point or not? But we had discussed that as well ...

My confusion “Oh ... Hello!” moment during the flight came (after we had aborted the approach and I discussed an emergency gear extension) when I looked at the owner and said ... “ok ... you can push the circuit breaker back in.” He looked at me and said ... “I didn’t pull any circuit breakers ... “ 

The conclusion,  more or less, was that the gear was functioning, was down and locked, but the indicator lights were all inoperative. An avionics shop had just completed some radio work, during which they had  (improperly) re-routed the gear light wires in such a way that we think they were caught and pulled loose when we moved the flight controls during the pre takeoff checks. To this day, I’m thinking the lights were already off when we took-off ... and we just didn’t notice? We’ll never know for sure ...

I had a similar thing in an Arrow I used to rent, but it turned out it was just that whoever flew it previously flew it at night and had turned the lights down.   I'd done a go-around to sort it out and figured it out on downwind, but it was definitely one of those "hmmmm...let's sort this out..." moments.

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Interesting comments on the number of gear indicator failures that people have had (in Arrows and Mooneys). It is a failure that I have never practiced or discussed. I do plan to present the gear indicator failure as a scenario in future flight reviews that I conduct. Hopefully, it will make it less confusing if someone sees it in the future.

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My wife and I returned from Nassau on Monday with a stop in Ft. Pierce to clear customs. The gear and gear warning system worked for all takeoffs and landings without issues. I do find myself looking at the breakers while the gear is transitioning to be sure nothing has tripped. It will be interesting to see if I retain that as a habit.

I have started to review the gear warning schematic and compared it to Vance’s excellent write-up in this thread. There are a few differences between the J model that I have and Vance’s F model. I have an annunciator panel instead of up/down lights but the signal going to the annunciator panel is the same. The Gear Warning breaker also powers a tone generator that is mounted on the inside firewall.

The J model doesn’t have access panels in front of the windshield as the F does so water is less likely to get to the back of the panel. It is still a possibility since there are screws, wires, etc. that do penetrate. I plan to check that carefully to make sure I don’t have a leak that needs to be plugged. I also plan to check the Gear Down Light and the Gear Down Limit switch that are under the floor. We had flown through a lot of rain that morning so I wouldn’t be surprised that I had water under the belly pan. I also plan to look for loose/broken/chaffed wires behind the panel and under the belly pan.

I have attached a drawing that I made of the gear connections. I have highlighted in yellow the circuit that the Gear Warn breaker powers when the gear is in the down position (the point that the breaker tripped). These are the components that I will start with.

I’ll report back with the results of my checks. It might be a few weeks as I have some commitments coming up.

Landing Gear Gear Warn Markup.pdf

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33 minutes ago, jcovington said:

I do find myself looking at the breakers while the gear is transitioning to be sure nothing has tripped. It will be interesting to see if I retain that as a habit.

Sounds like a good habit.  I'm going to steal that.

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Nice highlight technique JC!

Thanks for sharing that drawing.

best regards,

-a-

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Update: This past Saturday I had some time and decided I would spend the time in the hangar looking for the cause of the gear warning breaker trip. Looking over the gear schematic I decided to concentrate on the gear down limit switch, gear/stall warning audio tone generator and the throttle switch. At the last annual, the throttle cable had to be replaced due to it slipping. Knowing that the throttle switch is mounted on the cable I decided to check there first.

The throttle switch is a fairly inexpensive micro-switch with none of the contacts sealed. Since they aren’t sealed there is some play in the switch terminals. Next to the throttle switch, on either side, are two mounting screws that let you adjust where the switch will trip to set off the gear warning when the throttle is pulled back past a certain point. Fairly simple arrangement that works well.

I think at this point you can probably tell where this is going. When I crawled into the left foot well and looked at the throttle switch I noticed that the lower forward ring terminal was very close to the forward adjustment screw, that the cable bundle going to the throttle switch was unsecured and a rubber grommet around the throttle cable was partially out. I reached up and moved the wire bundle and the ring terminal contacted the forward adjustment screw. I looked for charred marks on the ring terminal to confirm that this caused the breaker to trip. I didn’t see any charring but it did look like some brown discoloration on the ring terminal although it was hard to tell for sure. It would have been nice to see the charring although with a one amp breaker I would have been surprised to see much.

The solution was to bend the ring terminal up away from the adjustment screw, to secure the cable bundle with a tie wrap and to reinstall the rubber grommet around the throttle cable. I know that there was enough movement in the cable/switch terminals to allow the ring terminal to contact the screw. I believe that movement of the throttle with the unsecured wire bundle was enough to have it happen in flight tripping the breaker when the gear was extended.

After finding the throttle switch issue I talked myself out of pulling the belly pan since I feel I found the issue. I will most likely pull the belly pan next time I do an oil change just for a general inspection.

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Excellent analytical work, and write-ups, Jim. I can remember when I was thin enough to get under the pilot foot well to check things out. Those days have passed.

Have a safe trip and see you and your beautiful bride in a couple of weeks. :)

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2 hours ago, fantom said:

 I can remember when I was thin enough to get under the pilot foot well to check things out.

I still can :D

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Do all electric gear Mooneys not have the sight glass in the floor between the seats? That has always seemed to me to be the fool proof indicator of gear down. If the little light burns out, I can always see it with the flashlight on my phone. 

One of the nice things about the manual gear Mooneys is that no lights, horn, or anything is required to verify gear down and locked.

I've been assuming the sight glass in the floor was basically the same thing for my K.

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Nice details, JC!

Random sparks inside the cabin would be bad...  as would be random vapors from leaky tanks...

Keep both the sparks and the vapors nicely contained.  :)

Thanks for the great follow-up!

Best regards,

-a-

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Do all electric gear Mooneys not have the sight glass in the floor between the seats? That has always seemed to me to be the fool proof indicator of gear down. If the little light burns out, I can always see it with the flashlight on my phone. 
One of the nice things about the manual gear Mooneys is that no lights, horn, or anything is required to verify gear down and locked.
I've been assuming the sight glass in the floor was basically the same thing for my K.


They do. If you pull the gear warning breaker on my plane, the gear indicator lights next to the switch and the floor indicator light won’t light. I suspect he was getting the correct mechanical indication on the floor but just couldn’t see it.

I had the light in the floor indicator stop working once. It’s really hard to see without a flashlight to illuminate it.


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33 minutes ago, gsxrpilot said:

Do all electric gear Mooneys not have the sight glass in the floor between the seats? That has always seemed to me to be the fool proof indicator of gear down. If the little light burns out, I can always see it with the flashlight on my phone. 

One of the nice things about the manual gear Mooneys is that no lights, horn, or anything is required to verify gear down and locked.

I've been assuming the sight glass in the floor was basically the same thing for my K.

I did have a manual downlock indicator in the floor. I did not have a gear down light or the light in the floor window. At the time I didn't understand the gear warning system as well as I do now. I was afraid that without the lights the gear was not locked. After Daytona Aircraft put the plane on jacks and explained the gear warning system I understood that the gear was down and locked. The only problem was the lights weren't lit.

Even with the new knowledge I have about the gear warning system I would still break off the approach to do the troubleshooting. I just wouldn't have the pucker factor now that I did then.

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Back when my gear motor breaker would trip, I would hear it go and also feel the gear not doing what they were supposed to do for the proper amount of time.     I am not sure if my transition instructor did it or I started it, but Gear Switch.  Wait a few.   Check Floor indicator.  Short short final, I check for Green light and check floor.  There are probably a couple other times I check.   A couple years ago when I videoed myself, I checked the gear 4 times.

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Another update: This past Saturday I took the plane up for a short flight since it hadn’t been flown in a couple of weeks. Coming back into the airport I put the gear down and had another gear warning breaker trip. Looks like my earlier diagnostic finding of the ring terminal rubbing on the throttle position switch was wrong or at least incomplete.

I am a lot more comfortable now that I know the gear is down even with the gear warning breaker tripped so I spent some time troubleshooting. I pushed the gear warning breaker in with the gear down and got the gear down lights with the breaker staying in. I cycled the gear up and the gear warning breaker tripped. Pushed the breaker in and cycled the gear down. The gear warning breaker tripped again. Pushed the gear warning breaker in again with gear down, got all the lights and the breaker stayed in. The problem has to be something within the gear unsafe circuit or perhaps a frayed/loose wire.

When I returned to the hangar I dropped the belly panel and looked at the wiring for the gear system. I didn’t see anything loose or frayed. That was as far as I got on Saturday.

This week I have spent quite a bit of time examining the gear wiring circuit to identify the likely points I need to check. I concentrated on the gear unsafe circuit and came up with the following items to check

1)      Connector RC09A/PL09A for loose pins/corrosion

2)      Connector RC14A/PL14A for loose pins/corrosion

3)      Connections on the up/down limit switches for loose wires/corrosion

4)      Replace D1 Diodes on RC14A/PL14A and RC09A/PL09A

5)      Look for frayed wires around the gear mechanism

6)      Test the 1 amp gear warning breaker

I have had several flights (about 10 hours total) with no issues with the gear warning breaker. When it happens it will consistently fail and then the next flight work with no issues. I think it is likely that the D1 diodes are going bad letting current flow where it shouldn’t. Since the diodes are located on the PL14A/PL09A connectors I will replace them while I look for bad pins/corrosion.

I will be playing find the connectors in the wire bundles on Friday. I’ll report back what I find.

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On 6/13/2018 at 9:41 AM, jcovington said:

Another update: This past Saturday I took the plane up for a short flight since it hadn’t been flown in a couple of weeks. Coming back into the airport I put the gear down and had another gear warning breaker trip. Looks like my earlier diagnostic finding of the ring terminal rubbing on the throttle position switch was wrong or at least incomplete.

I am a lot more comfortable now that I know the gear is down even with the gear warning breaker tripped so I spent some time troubleshooting. I pushed the gear warning breaker in with the gear down and got the gear down lights with the breaker staying in. I cycled the gear up and the gear warning breaker tripped. Pushed the breaker in and cycled the gear down. The gear warning breaker tripped again. Pushed the gear warning breaker in again with gear down, got all the lights and the breaker stayed in. The problem has to be something within the gear unsafe circuit or perhaps a frayed/loose wire.

When I returned to the hangar I dropped the belly panel and looked at the wiring for the gear system. I didn’t see anything loose or frayed. That was as far as I got on Saturday.

This week I have spent quite a bit of time examining the gear wiring circuit to identify the likely points I need to check. I concentrated on the gear unsafe circuit and came up with the following items to check

1)      Connector RC09A/PL09A for loose pins/corrosion

2)      Connector RC14A/PL14A for loose pins/corrosion

3)      Connections on the up/down limit switches for loose wires/corrosion

4)      Replace D1 Diodes on RC14A/PL14A and RC09A/PL09A

5)      Look for frayed wires around the gear mechanism

6)      Test the 1 amp gear warning breaker

I have had several flights (about 10 hours total) with no issues with the gear warning breaker. When it happens it will consistently fail and then the next flight work with no issues. I think it is likely that the D1 diodes are going bad letting current flow where it shouldn’t. Since the diodes are located on the PL14A/PL09A connectors I will replace them while I look for bad pins/corrosion.

I will be playing find the connectors in the wire bundles on Friday. I’ll report back what I find.

My similar situation was a foreign metal object that had fallen into the throttle position switch that was causing a short to ground a popping the gear light breaker ('69 F model though) 

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On ‎6‎/‎13‎/‎2018 at 9:41 AM, jcovington said:

This week I have spent quite a bit of time examining the gear wiring circuit to identify the likely points I need to check. I concentrated on the gear unsafe circuit and came up with the following items to check

1)      Connector RC09A/PL09A for loose pins/corrosion

2)      Connector RC14A/PL14A for loose pins/corrosion

3)      Connections on the up/down limit switches for loose wires/corrosion

4)      Replace D1 Diodes on RC14A/PL14A and RC09A/PL09A

5)      Look for frayed wires around the gear mechanism

6)      Test the 1 amp gear warning breaker 

 

A final follow-up (at least I hope). A few weeks ago I dropped the belly pan and removed some of the interior pieces so that I could find the gear warning connectors and diodes.

The RC14A/PL14A connector with the D1 diode attached is located beside the pilot seat at the point that the wiring harness passes through the floor. I couldn’t find any loose pins or corrosion on that connector. I held off on replacing the diode as I wanted to look at the other connections first.

The RC09A/PL09A connector with the D1 diode attached is not near as easy to access. It is behind the pilot side panel about 6 inches below the gear switch. I couldn’t find any loose pins or corrosion on that connector although it was very difficult to access. I didn’t replace this diode either as the radio racks would have to be removed to get enough slack in the wiring harness to replace the diode.

The next step was to check the up/down limit switch connections under the belly to see if any were loose. I found one of the ring connectors on the up limit switch was fairly loose. I was able to get about a half turn on the screw when I tightened it. While I had the belly pan off I checked the remainder of the connectors (gear and flap) and everything else was tight.

I have about 20 hours and 20 gear cycles since I tightened up the loose ring connector on the up limit switch without any issues. I believe that the up limit switch loose connector was causing enough extra resistance to cause the 1 amp breaker to trip when the gear was in transit. If it occurs again then I will have to replace the diodes and breaker as there isn’t much left. I hope this is my last post to this thread but if the breaker trips again I will report back.

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It was a chat with Joey Cole that convinced me to purchase my Mooney.  He's good people.  Hope the OP can get his issues fixed, sounds like drag.  He certainly dealt with it correctly.

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