PA28 Pre-flight checks/plug leads?

[Thumpango]

Do you check the condition of the spark plug leads when doing your pre-flight checks on a PA28?

I did this morning and found that the braid was corroded completely through on one plug leaving just the white inner conductor connected, on exercising gentle lift on this lead it slipped out from the plug!

Flight was cancelled and aircraft faulted.

Anyone with similar experience? I am interested because CFI who wasnt there to witness this event, said we dont normally check the plug leads and seemed to think that I had ripped the wire out!:{

[Speedbird252]

I reckon you did good thumpango, the walkround is a serious part of the pre flight and youve just demonstrated why.

Mildly amused at your CFI saying that they dont usualy check them. Ive got two PA28 checklists, and a PA28 Pilots manual, and all of them quite clearly list the plug leads as part of the engine compartment check.

I have seen the brading a bit thin, but not worn to excess and Ive certainly never had a lead come out of the plug! I dont pull hard on them, but I sure as hell make sure they are connected to the plug ok.

What do you use as a checklist for the walkround?? Is it the clubs own type of checklist, or one of those say produced by AFE?

Regards,

Speedy:ok:

(edited cos i carnt spel)

[Evo]

Yep, was taught to do it when possible (i've flown one PA-28 where you can only check the oil, Speedy will know which one). I always try and do a 'nothing dangling, nothing dripping' check (to quote FFF) when I take a look at the engine :)

[ratsarrse]

I pretty much look for anything at all that looks out of the ordinary in the engine compartment (no matter what's explicitly stated in the checklist) as that is what I've been taught. Checklists just give you the bare essentials, in my opinion, and after all they are check lists, not do-lists! AFE checklist is preferred at the school I'm training at, but I suspect that I'll develop my own at some point in the furure.

[Mike Cross]

Another one worth doing is a gentle waggle of the exhaust where it exits the cowling to check for excessive movement.

On one occaison this revealed stripped threads on the retaining studs at the cylinder head, on another it revealed a cracked exhaust within the heat exchanger. Happened to be on the carb air side but could just as easily have been on the cabin heat side. Carbon monoxide is not nice in your cabin.

I've also found a pair of pliers sitting on top of the engine following maintenance.

Mike

[knobbygb]

Hmmm... I always check the leads to the plugs, and there is often at least one where the braiding is worn through and the white inner is showing. I was lead to believe this was normal, so next time I'll certainley be giving them a gentle tug to see what happens. Thanks for the 'heads up' Thumpango. I suppose having two plugs in each cylinder means the a/c isn't exactly going to drop out of the sky if a lead DOES work loose in flight, but still worth avoiding.

Incidently, I also fly the Robin 2160 where it isn't possible to check the condition of anything like this as the cowling is fixed in place. Surely these things are important (as demonstrated above), in which case there should be a way of checking.

[Edit: Actually, thinking about this in hindsight, perhaps it's everybody tugging at the leads 7 or 8 times a day that causes the problem in the first place, who knows?]

[matspart3]

Always check them if I can, found all the top side plug leads hadn't been re tightened once, after the aircraft had just come out of engineering

[FlyingForFun]

Do you check the condition of the spark plug leads when doing your pre-flight checks on a PA28?I check everything I can see. On a PA28, yes, that includes plug leads. I'm always a little worried when I fly aircraft (like both of those I fly regularly at the moment) where I can't open the cowling on the pre-flight and have a good look.

FFF's tip for the day: every time you fly with a new instructor, whether it's just a quick check-out or whatever, get the instructor to pre-flight, and talk you through what he's doing. Chances are, he'll point out something that you'd never thought to look at. I found this when checking out on a PA18 at a new club a couple of years ago. Although I was current on the PA18, the instructor insisted on showing me how to pre-flight it, and immediatley showed me how to check the engine mounts, which is something I'd never thought of checking before. My pre-flight check-list for every aircraft I've ever flown is a continually-growing list.

FFF
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[bertiethebadger]

Another check that you could add to the PA-28 ( & prob other types ) is the propeller drive belt tension.

If you put you hand into the starbord air intake & reach behind the spinner, you will feel the drive belt. I usually check for tension & to fell if the edges feel worn.

[tyro]

I used to get quite worried seeing spark plug leads with worn braids at he plug end. However it didn't seem to bother those instructors I've mentioned it to.

Does anyone know whether the braid serves to shield the avionics from interference, or to give mechanical strength to the cable, or something else?

[MikeeB]

Another check missing off the flipsheet thing I have for PA-28's is the nut that holds the elevator(stabilator(sp?)) control on. It's actually inside the aeroplace, but you can see it by bending down and looking in the hole directly at the rear of the aircraft.

I asked the question of why it doesn't have a lockwire on it, and was told its a nylon thread nut.

Quite why something so important (IMO) is missing off the list, I have no idea.

[Ludwig]

If I feel the need to check something on a walkround which I could not see, and I was told by the CFI not to bother cuz we never do, I would be even more inclinded to check it, and probably even more besides - you will look at right chump sitting in a field just becasue someone said not to bother!
The whole question of the walk round is often glossed over in training; how many people do you see wandering round checklist in hand checking things per the book, but not having a clue what they are looking at, whether it is right of not, or what level of deviation form the norm is acceptable?

Interesting point about damage due to constant wiggling by load of checkers though!

[Windy Militant]

One check I was shown which I've not seen many people do is to make sure that there's no movement between the elevator sides. Certain A/C types either have a flange in the middle which can come loose or there may be damage. Now I always try a gentle wiggle during the walk round. My instructor at the time had previously had a nasty experience with this so was keen not to be caught again!

[QDMQDMQDM]

Check the thin copper primer lines. These often fracture, or at least they do on Super Cubs with 0-320s, so I presume they do on PA28s too.

David

[david viewing]

MikeeB

That bolt is known here as a 'Jesus' Bolt. Apparently that's what people say when it falls off.

David

[Thumpango]

Thank you for your comments and suggestions for other items to check! I have never been shown how to check the alternator belt but I do know about the Jesus bolt! Although, there again, it is not on the check list. I think someone told me about this somewhen.

My checklist, as supplied by the school, does not mention to check the condition of the spark plug leads or the alternator belt.
I only check these items because I deem it sensible and would be the sort of basics I would check on my car- (not before every trip though!)

I take the point that if 7 or more students check the plug leads every day and give them a gentle 'rocking' to check they are secure this could well cause damage.

Just a few other observations now, the landing lights on the PA28s I fly sometimes have blown. The school has introduced a rule that when doing circuits the landing light should not be on. Thereby saving wear on these items.

Likewise the Pitot heater. This is on the checklist, but very often is not working with both elements, ie. no warmth from it on the initial walkaround and check of lights, stall warner etc.

No ammeter indication either on the instrument checks, (both elements dead?) apparently 'no problem' as we dont use the pitot heater anyway (presumably for the work we are about to do).

Pprune is a good sounding board for these observations, any comments, as before, are very gratefully received. When you are a student you don't necessarily know what the 'Norm' is.

[WelshFlyer]

like many others have said, best to be on a lookout for anything unusual - you get sick and fed up of looking at aero engines, but by god you know if anything is out of place by the time you've finished:)

Also it helps to have other mechanical experiance as well - some things are not entirely obious on inspection:ok:

WelshFlyer.

[RW05]

I've also found the plug caps loose on a PA28 straight out of mainenance. I think they work loose in the first ground run. I've also found a cracked weld in an exhaust that obviously hadn't just happened, so I wonder how many others had missed it.... I've seen someone 'preflight' an aircraft by walking up to it, looking at it (presumably to check it was the right aircraft?) and walking away again. Anyone else have a 'people I would never get in an aeroplane with' list?

[Thumpango]

Interesting RW05,

the aircraft I had with the broken spark lead had only been serviced the week before.

Another thought, with the stresses and strains a training aircraft undergoes, heavy landings etc - (yes, I am to blame as well) how often is the airframe checked.

The wing spars must take some heavy loads on occassions so what checks are made for metal fatigue? Spark plugs, landing lights and pitot heaters I can cope with, but I doubt a successful outcome if a wing comes adrift. These are 15-20year old aircraft I am flying.

Um, I wish hadn't thought about that now!

[FlyingForFun]

Bertie,Another check that you could add to the PA-28 ( & prob other types ) is the propeller drive belt tensionUnless I'm very much mistaken, the prop on a PA28 (and most aircraft, in fact) is bolted straight onto the front of the engine - it's not driven by a belt. I'd imagine the belt you're thinking of is the alternator drive belt? (The only piston engine I'm aware of - although I'm sure there are others - where the prop doesn't bolt straight onto the front is the Rotax, and that uses a gearbox rather than a belt to drive it.)

FFF
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[bertiethebadger]

FFF,

Yourself, & others, are correct about the function of this belt.

Still worth a check though.

[Thumpango]

Pre-flighting a PA28 tends to vary according to the school checklist, I try to go beyond this and check everything I see! I am up there flying this machine and ultimately my life depends on what I have or have not checked/seen.