Magneto 500 hr Inspection Requirement

Tom-D said:
like the rear fuselage bulkhead cracking, there is no AD, but every 170 type know that is where the elevator stops are and they get banged a lot and the stops get pushed thru the aluminum bulkhead. I have replaced 4, it requires a fuselage jig, and about 5 days labor. at today shop rates.
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Tom,

Is this the area directly below the vertical stab where there is a bracket riveted to a bulkhead?

The A&P's report lists it as 'L/R elevator bellcrank support inside tailcone' The bulkhead there seemed fine, but there were cracks coming out of the topmost rivet holes on the bracket - one on each side. He felt that it could probably be repaired with doubler plating.

Edit:
Looking at the Cessna Illustrated Parts Catalog for the 1948 170, page 38, it would be the brackets labelled 55 and 56 attached to bulkhead 54.
 

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Fearless Tower said:
I've seen at least one quote for 500 hr inspection that was $250 per mag just for the inspection and 100/hr for repair costs plus any parts. Brand new slick mags and harness kit is around $21-2200.

But then again, I will admit that I am a newbie as a potential first-time plane owner.
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I recently purchased 2 new Slick mags for $1200. The harness would add an extra $150.00.

When it comes to aircraft parts shop around.
 
We might have two mags but I have found that it can cause considerable inconvenience and expense to let them go until one fails. Most engines have one impulse mag, and as long as it's sparking enough it'll start, but if it gets just a bit weak there comes a time when it refuses to spark and the other (non-impulse) mag can't spark at starting speed. Now we're faced with repairs, often in some really stupid spot far from home or a competent shop and it gets time-consuming and expensive.

So in the flight school we do the mag inspections every 500 hours. Once one gets proficient at it, the two can be taken off, cleaned and inspected and worn stuff replaced, and put back on and timed, in a couple of hours unless they're on some airplane whose designers figured it would be hilarious to put the mags someplace where the engine nearly has to come off to get at them.

And so, after learning some stuff the hard and expensive way, we don't have mag failures. And we buy vacuum pumps with the inspection ports and replace those when the vanes are worn to manufacturer's limits, so we don't have vacuum failures, either.

Dan
 
Dan Thomas said:
We might have two mags but I have found that it can cause considerable inconvenience and expense to let them go until one fails. Most engines have one impulse mag, and as long as it's sparking enough it'll start, but if it gets just a bit weak there comes a time when it refuses to spark and the other (non-impulse) mag can't spark at starting speed. Now we're faced with repairs, often in some really stupid spot far from home or a competent shop and it gets time-consuming and expensive.

So in the flight school we do the mag inspections every 500 hours. Once one gets proficient at it, the two can be taken off, cleaned and inspected and worn stuff replaced, and put back on and timed, in a couple of hours unless they're on some airplane whose designers figured it would be hilarious to put the mags someplace where the engine nearly has to come off to get at them.

And so, after learning some stuff the hard and expensive way, we don't have mag failures. And we buy vacuum pumps with the inspection ports and replace those when the vanes are worn to manufacturer's limits, so we don't have vacuum failures, either.

Dan
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OBTW,,,,, a failure of a mag is a high mag drop,,, not a total disintegration where the engine falls off the aircraft.

High mag drops should be fixed, not put off until next annual.

Why don't you simply go back to the old Pesco wet pump, and stop worrying about a failure,
 
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Rotor&Wing said:
I recently purchased 2 new Slick mags for $1200. The harness would add an extra $150.00.

When it comes to aircraft parts shop around.
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Did you read the service difficulty reports before you bought them. ?????
 
Fearless Tower said:
Tom,

Is this the area directly below the vertical stab where there is a bracket riveted to a bulkhead?

The A&P's report lists it as 'L/R elevator bellcrank support inside tailcone' The bulkhead there seemed fine, but there were cracks coming out of the topmost rivet holes on the bracket - one on each side. He felt that it could probably be repaired with doubler plating.

Edit:
Looking at the Cessna Illustrated Parts Catalog for the 1948 170, page 38, it would be the brackets labeled 55 and 56 attached to bulkhead 54.
Click to expand...

The bulkhead I mentioned is the one you sited. any cracks must be repaired, the Cessna structural repair manual has no repair for the bulkhead, so it is a replacement. which is a case where the fuselage must be separated at the rivet row that holds the tail cone in place.

Does the aircraft that you are looking at have a dorsal fin?

The 48 came with out one, if it has one look for the field approval to install it.
 
Fire the parts shotgun and change the mags and the harness and the plugs.
 
Tom-D said:
The bulkhead I mentioned is the one you sited. any cracks must be repaired, the Cessna structural repair manual has no repair for the bulkhead, so it is a replacement. which is a case where the fuselage must be separated at the rivet row that holds the tail cone in place.

Does the aircraft that you are looking at have a dorsal fin?

The 48 came with out one, if it has one look for the field approval to install it.
Click to expand...

No dorsal fin.

As far as the bracket goes, since the bulkhead itself is not cracked, would you agree that the cracks in the bracket could be addressed without too much trouble?
 
Fearless Tower said:
No dorsal fin.

As far as the bracket goes, since the bulkhead itself is not cracked, would you agree that the cracks in the bracket could be addressed without too much trouble?
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Just replace the bracket, that's the easy part.
 
Tom-D said:
before any one runs out and buys a new slick they should read this.

http://www.lycoming.textron.com/support/publications/service-letters/pdfs/SL173C.pdf

Point being, they know their product is a POS, and can't do any thing about it until they ask the FAA for a AD on their products. then they will obtain the same reputation as Bendix loaded with ADs.
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They fixed a bunch of problems those older mags had when they came out with the 4300/6300 series and introduced a bunch of different problems. Now they have incorrectly-assembled mags with bent coil tabs that wear the carbon brush out in no time flat. Found a bunch of those. Then they cheaped out on the plastic points cam and had a bunch wearing down real fast so the timing got late and the E-gap got screwed up. Late, weak spark. SB 2-08A and SB3-08A. I've found the plastic distributor gears incorrectly installed and shedding plastic dust that fouls the points. Less than 100 hours on new mags. When we get a factory-overhauled Lycoming engine I check the timing (it's often off a few degrees) and sometimes find the mags wet with machine oil inside after the new engine had significant mag drops on initial runup.

Looks like they're hiring the cheapest engineers and factory labor they can find. I bet the Chinese could easily build a better mag (for a lot less money, too) at this point. North America seems to have lost its sense of world-beating quality, eh, Tom?

Dan
 
Dan Thomas said:
North America seems to have lost its sense of world-beating quality, eh, Tom? Dan
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When I was a kid we had a 1928 Farmall tractor, with a Fairbanks moirris mag, when we quit farming it went to my Sister's farm, they used it for 20 odd years, then it sat in a creek bed for another 15-20 years, the guy who bought it when they quit farming, started it with out doing any thing to the mag. and drove it out of the creek bed. It's now about 20 miles from where I first saw it running a belt powered saw mill, and I don't believe it has ever been rebuilt or messed with.

I saw the old cast iron monster last summer while we were back east in NY.

new isn't always better.
 
Tom-D said:
When I was a kid we had a 1928 Farmall tractor, with a Fairbanks moirris mag, when we quit farming it went to my Sister's farm, they used it for 20 odd years, then it sat in a creek bed for another 15-20 years, the guy who bought it when they quit farming, started it with out doing any thing to the mag. and drove it out of the creek bed. It's now about 20 miles from where I first saw it running a belt powered saw mill, and I don't believe it has ever been rebuilt or messed with.

I saw the old cast iron monster last summer while we were back east in NY.

new isn't always better.
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I have 65-year-old Case mags on my A-65. They make a hotter spark than the new Slicks. But they're unshielded and that's a problem these days if one wants radios.

Dan
 
Tom-D said:
The bulkhead I mentioned is the one you sited. any cracks must be repaired, the Cessna structural repair manual has no repair for the bulkhead, so it is a replacement. which is a case where the fuselage must be separated at the rivet row that holds the tail cone in place.

Does the aircraft that you are looking at have a dorsal fin?

The 48 came with out one, if it has one look for the field approval to install it.
Click to expand...

Tom
The vertical Stab change is in the Type Cer.
 
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