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-   -   PA28 smoke source mystery (https://www.pprune.org/tech-log/654922-pa28-smoke-source-mystery.html)

kghjfg 23rd Sep 2023 09:50

This is an interesting thread.

You won’t answer any specific questions, you seem to think you shut down by “turning the ignition off”

and you’re not sure where the fire extinguisher is on a PA28.

(in fact, you state it’s in the back?)

I asked you a couple of simple questions, which may identify a mag switch failure, but you chose to ignore the questions. ( if the mag switch had failed, that might cause it. )

I find it odd that you call the mag switch the “ignition” like you would on a car.

Anyway, why all the vagueness, and if you’re competent to land away, why are you not competent to look behind the bottom of the panel.

Are you a student by any chance?



Anyway, was the smoke near the timing lever?
Just answer me that, if nothing else.

DuncanDoenitz 23rd Sep 2023 10:39

Excuse me wading in, but we're at Post 21 now and I see no indication that any "qualified" person has looked at his suspected problem, or that the maintenance organisation/mechanic has been consulted about it. With the greatest respect to the pilots and Instructors on here, and on-site, flying is your area of expertise, fixing things is ours. <br /><br />I'm 3 or 4 years retired now but, back in the day, there were a number of Service Bulletins extant on the subject of ignition switches. They go wrong; sometimes seriously. A mechanic is best placed to give advice, discuss possible failure modes and to gain better access to the switch, its wiring, and adjacent components to perform a proper inspection.

Edit; Appreciate and acknowledge Uplinker's post below. I should also add that, if the OP is a student, I appreciate that the presence of an authority-gradient may not make this as easy as "just do this, then do that".

Uplinker 23rd Sep 2023 11:19

Quite so, but FWIW, in post #2, I did imply that an engineer would be required to investigate this.

A small amount of smoke could be an electrolytic capacitor popping, or could be an arc between worn switch contacts igniting a small amount of oil or grease, or could be a shorted wire overheating its insulation. Whatever the cause, it needs investigating by a qualified engineer.

But let's not be too hard on the OP - it seems to me that the company were less than sympathetic when they reported the fault, and shame on the company for not taking this seriously and being much more proactive - have they not undergone CRM training?
Given the apparent dismissive attitude of the CFI, perhaps the OP felt they could not talk to anyone in the company - hence them asking for advice here. It is not necessarily easy to go up to other instructors whom you don't know in the crew room and ask their opinion or advice.

We all (should) know how serious, smoke in the cockpit can be, and I am very surprised at the CFI's attitude and apparent lack of concern regarding the fault.

EXDAC 24th Sep 2023 02:38


Originally Posted by hedgehopper (Post 11507426)
3. when changing tanks in flight or turning off on the ground, you move your left leg to a position under the seat thereby allowing easier access the fuel valve, and “Momentarily Kick” the trigger allowing a short burst of medium to escape.

How many aircraft fire extinguishers do not require removal of a safety pin before the exinguisher can be activated? All of the small halon and powder extinguishers I have at my house require a pin to be pulled before they can be activated. I'm confident the ones in my aircraft are the same.


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