Group Poll: How many hours between mag overhauls?

You have two of them. If one fails you can continue to fly on the
other. Best thing to do is replace ONE. Then you have one new one and
one old one. I consider mags to be 2000 hour lasting accessories, or
replace when they fail. You could easily argue that you don't have to
replace them until you rebuild the engine. It really is up to you. But
with mags, you do have a backup if one fails and the likelyhood of both
failing at once is small.

Doug wrote:

You have two of them. If one fails you can continue to fly on the
other. Best thing to do is replace ONE.

Better than replacing two?

My Slicks gave a problem on left mag drop at 1200 hrs and were repaired.
Until the problem, mag maintenance hadn't even occured to me - there's
just too many things to be aware of in aircraft ownership - I guess that
one just slipped under the radar.

Tony
--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

In article ,
"Jim Burns" wrote:

To the group: At how many hours do you rebuild or replace your mags? or do
you wait for a problem to arise first?

Jim

O-320 that had a brand new pair of Slicks installed when the engine was
field-overhauled 6 years ago. At the 500 hour mark last annual, we
pulled them and examined them. My A&P said they still look like new
inside.

"tony roberts" wrote in message
news:nospam-A30BC4.22543423042005@shawnews...
My Slicks gave a problem on left mag drop at 1200 hrs and were repaired.
Until the problem, mag maintenance hadn't even occured to me - there's
just too many things to be aware of in aircraft ownership - I guess that
one just slipped under the radar.

Tony

Slick says at 500 hours they should be pulled and inspected. Mine were in
near new condition at 500 hours.

Mine were just rebuilt 4 hours ago and now I have left mag problems
again - it has dropped 100, 400, and cut out.
My A&E is away so I'm grounded until he gets back


Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

In article ,
"Dave Stadt" wrote:

"tony roberts" wrote in message
news:nospam-A30BC4.22543423042005@shawnews...
My Slicks gave a problem on left mag drop at 1200 hrs and were repaired.
Until the problem, mag maintenance hadn't even occured to me - there's
just too many things to be aware of in aircraft ownership - I guess that
one just slipped under the radar.

Tony

Slick says at 500 hours they should be pulled and inspected. Mine were in
near new condition at 500 hours.

On Wed, 20 Apr 2005 06:26:43 -0700, "Jim Burns"
wrote:

To the group: At how many hours do you rebuild or replace your mags? or do
you wait for a problem to arise first?

Jim


Back to you: What type/manufacturer of magneto on what engine
installation?

The answer varies from magneto to magneto and installation to
installation.

For instance, I can't recall ever doing a manufacturer-mandated (as
opposed to FAA mandated) 500 hr inspection on a Slick magneto that
couldn't use a set of new points and the crap dug off of the
distributor block.

I can't recall ever doing a 1000 hr inspection on a Slick magneto that
didn't need a set of new points and a new distributor block.

Unless prices have changed a big bunch, you can't buy a new set of
points and a new distributor block + an hour or so of labor for much
less than the price of a new Slick magneto.

I would really not get into the practical maintenance requirements for
a dual Bendix/TCM magneto, given a choice.

TC

Presently I have Slick 4200 (4201 and 4251 as I recall) Series mags on
a Cessna 172M.

The timing to the engine has not changed since the initial new
installation, and remains within specs. They are now at about 900 hrs
since new. This is flat country so I 'm leaving them alone for now.

I've never experienced a rough mag since I quit renting aircraft 1600
hrs ago. I'm now at 1700 hrs TT over 40 years all (well most) with 80
octane or autofuel.

Hey TC... 200 Series Bendix shower of sparks type.

Jim

wrote in message
...
On Wed, 20 Apr 2005 06:26:43 -0700, "Jim Burns"
wrote:

To the group: At how many hours do you rebuild or replace your mags? or
do
you wait for a problem to arise first?

Jim


Back to you: What type/manufacturer of magneto on what engine
installation?

The answer varies from magneto to magneto and installation to
installation.

For instance, I can't recall ever doing a manufacturer-mandated (as
opposed to FAA mandated) 500 hr inspection on a Slick magneto that
couldn't use a set of new points and the crap dug off of the
distributor block.

I can't recall ever doing a 1000 hr inspection on a Slick magneto that
didn't need a set of new points and a new distributor block.

Unless prices have changed a big bunch, you can't buy a new set of
points and a new distributor block + an hour or so of labor for much
less than the price of a new Slick magneto.

I would really not get into the practical maintenance requirements for
a dual Bendix/TCM magneto, given a choice.

TC

On Mon, 25 Apr 2005 05:36:29 -0700, "Jim Burns"
wrote:

Hey TC... 200 Series Bendix shower of sparks type.

Jim


Visual inspection of points every 100 hrs/12 months whichever came
first with point replacement based on condition noted. Doesn't take a
rocket scientist to pop the contact cover screws and notice that the
points are worn/gap out of limits (too big if the contacts are eroded,
too small if the plastic cam follower is worn).

1000 hr/5 year internal lubrication following the TCM/Bendix
recommended procedures.

Overhaul/replacement at normal TBO interval for the engine they were
mounted to.

As others have mentioned, if the 500 hr impulse coupling check was
mandated, the impulse mag/mags were pulled for coupling inspection,
internal timing check/point replacement (again determined by
point/follower condition).

Lycoming SI 1291 (as I recall) addresses more frequent inspection of
the distributor block on magnetos used primarily at high altitudes. I
don't have a copy of it handy, and do not remember the hourly
requirements.

TC