The Hall of Flame

Bob Weber

Pre-takeoff checklist
Joined
Jan 29, 2019
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Autopilot Whisperer
Austrailian hall of flame.jpg

We found this in an old Cessna twin while troubleshooting a trim issue.. Can you spot the problem?
 
Yep, but we also need to see the damage from the loose connection. Not to mention, where's the screw floating around in an environment that does not react well to metal things floating around.
 
There's always a couple screws, bolts, or nuts left over when you put things back together, you know that!
 
The screw is visible... Also look at the discoloration of everything that got hot.
 
Ah... So we're playing "Find Waldo"? ;)

Hi Bob!!!
I wish I could say that I miss making the flight across the lake to come see you.
You put up your own shingle! Awesome!

Don Thanks!! Yes I did, and now you don't need to fly to me anymore, it's all over the phone.
 
half way down, right side looks like a wire is taking power off the bus (unprotected)
 
I'm looking, any way you can screenshot the area?

The 'mounting' screws for RM-2 (and maybe RM-1) has a yellow terminal attached, leading to somewhere/something.
I'm guessing that's what he's talking about.

Seems also the case for the lower terminals in the picture (without protection), even the one with the missing screw...but maybe they have built in protection? Like a USB charging port, etc.?
 


Yet another great point! I'm guilty myself of doing this, that appears to be a supply wire for the buss added to the (hopefully) longer screw on the breaker. This connection should be made with a dedicated hole in the buss using good hardware including a metal locknut.
 
Surely that wire is supplying a fuse or cb somewhere close by. But still not drawing from a good place.
 
Question: Why do they still use slotted screws in a spot that is nearly inaccessible, in most aircraft?
 
may not be violations, so much as ‘electrical unpleasantness’

1 do not see washers
2 bend in bus could have consequences later
3 previously discussed tap. could be ok; I’d have to look it up. Either way, don’t like.
4 if not a factory produced bend, could be ‘well along the plastic range’ for that metal

6 is that discoloration of the tefzel or...exposed wire?
7 typical messiness of older a/c; very common but undesireable


6D4C006D-2722-44A4-85C9-C300CAEC17F4.jpeg
 
Sorry for the delay, I wanted to make a thorough reply. These are all good things to notice and a closer check is needed.
1 There is a washer, it is badly discolored from the heat caused by a loose connection. The picture is a little blurred but the screw looks a little discolored as well. The heat could very well have transferred into that breaker, for the $30 I would replace it.
2 I would inspect the breaker for damage from when what ever bent the buss bar, if no damage carefully straighten things out.
3 previously discussed method is the way to do it, look it up and get back to us.
4 An uncomfortable looking bend, though common. I always inspect to see if the wire is still loomed tight and it hasn't been working the bend any more. Cessna did this quite often.
6 I'd need a better look at it to tell, I spotted the discolored nylon insulation of the disconnected wire, discolored tefzel area of the wire right under your number 1. Look at the dulled screw heads, they were loose at some point.
For four decades I've been looking at these panels and tightening up every connection that's loose, like I was taught.
I preach this very thing to everyone I talk to.
This is still ongoing down undah I will update when completed!
 
Question: Why do they still use slotted screws in a spot that is nearly inaccessible, in most aircraft?
The breakers come with them, as long as they're tight, they're fine.
 
Happy ending update for a new found Mate in Australia. His engineer replaced the burned stuff and checked every other connection. Everything was tight, the panel was reconditioned 5ish years ago so it was completely removed from all of the breakers, and reassembled.

He flew it the first time in the last day or so and saw the failure I was helping with. We went over some ground checks, and a very detailed explanation of how the system works. He reseated some connectors using Stabilant 22, and tied up some loose wiring. We also discussed his habits on final, I suggested he drop the gear upon GS aquire.

He just called me elated with seeing it fly better than ever, music to my ears!
 
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