boscomantico wrote:
With a 40 year old aircraft the one just buys „off the market“, without knowing its exact history, one just has to expect every songle electrical connection there is to be marginal at best.
Yes that seems to be the case here.
boscomantico wrote:
I would first spray some WD40 into the PTT buttons for now.
That’s a joke, right? I can’t imagine spraying any fluid into an electrical switch is a good idea, unless I want stuck mike issues.
I would not put it anywhere near so pessimistically but the real issue is that very few avionics installers understand what each connection actually does and their troubleshooting involves mostly replacing stuff which is obviously expensive.
The whole GA scene struggles with this problem.
Was a prebuy inspection done, under the covers, to see how clean or dirty it looks?
WD40 does help with electrical connections, used sparingly. But things like a PTT switch I would just toss out instantly. OTTO make some nice ones, also APEM.
If a load of other stuff stopped working too it could be widespread corrosion but more likely a loose connector.
PTT switches – aaaarghhhh !!! I’ve lost track how many we change in the club on a regular basis. These things just die….
That is because most people install the cheapest crappiest 20p Chinese ones. Spend 20 quid plus for a milspec sealed one, which can be used when you smell fuel…
Peter wrote:
Was a prebuy inspection done, under the covers, to see how clean or dirty it looks?
Yes a pre-buy was done, though I’m not sure how thorough it was behind the panel. I have to say I was a bit naïve regarding A/C electrical wiring. Having grown up with a EE and spent many hours building circuits, computers, etc., I know my way around electronics pretty well. But the mess of white behind the panel, with manually wired connectors was quite a shock. Looking at it makes me wonder how anything ever works reliably!
172driver wrote:
These things just die….
This is actually comforting, and something you don’t realize when you rent for so many years. Is replacing a PTT something I can do as an owner? And does it pull easily out of the yoke on a Socata TB10?
Peter wrote:
That is because most people install the cheapest crappiest 20p Chinese ones. Spend 20 quid plus for a milspec sealed one
Well, we put the best we can into our Cessnas, and they still die regularly. Of course they get trashed much more in a club environment than in a private owner situation, but frankly we treat them as consumables.
dutch_flyer wrote:
Is replacing a PTT something I can do as an owner?
I don’t think so, but not 100% sure, @Peter will know.
dutch_flyer wrote:
But the mess of white behind the panel, with manually wired connectors was quite a shock. Looking at it makes me wonder how anything ever works reliably!
That was exactly what I was thinking when confronted with the situation behind my panel. It’s just a mess. Single white wires all around that space, and even come to rest on moving cables of the steering control (stabilator) to slowly turn themselves into ground contacts. It is near-impossible to find yourself through this mess, and I start to think that this is done by purpose. It was set up by an avionics store with a real good reputation, and decades of experience in this field. Whoever did this either wanted that any maintenance work involves as many hours as possible, or that any highly aspirated owner shall be kept from touching anything.
My planes under panel wiring was a total mess when I bought it, very much as @UdoR describes, fixed when a friendly A&P spent 5 or 6 Saturdays circa 2012 slowly cleaning up the entire thing from stem to stern. The wiring and unused equipment removed weighed 14 lbs. He was interested in the plane and just decided to help, labor rate worked out to $25/hr. He’s been on my Christmas list ever since.
I just replaced both PTT switches with new ones from Otto, along with new old stock OEM stick grips. I made a ‘science project’ out of it because I wanted the push buttons to protrude through the rubber grips, with the hole punched from the inside and no nut visible.
The only way you get this level of attention to detail is with owner awareness and involvement.
dutch_flyer wrote:
That’s a joke, right? I can’t imagine spraying any fluid into an electrical switch is a good idea, unless I want stuck mike issues.
He did not say drench them. But a quick spray and a few presses can actually sort dirt issue quite quickly. Worked for me before, but only if the switch is well accessible. And then of course allow it to dry.
Same thing with the plugs, which could explain why the switch (which I’d put safely away in your flight bag eventually, brilliant solution if one of them breaks for real) won’t work now. A bit of contact spray, plug-unplug a couple of times and dry with a q-tip. Usually does the trick.
If it is the audio panel, that is a different story altogether…. hope not.
