Lyc O-235 How much room needed between mags and firewall to remove mags

[DonMorrisey]

Hello folks. My kitplane manufacturer is ready to fabricate my engine
mount and the Lycoming O-235 I have chosen is near the weight limits
that my plane can handle. I am trying to find the answers to two
questions:

1. The distance needed between the mags and the firewall to be able to
remove the mags for service without having to remove the engine?

2. The published length, by Lycoming, of the O-235 is 29.05 inches.
I have been trying to locate a dimensioned drawing to verify if this
measurement includes the mags. Does anyone know where to locate such a
drawing or know how else I can verify that information?

Thanks. Don...

[Drew Dalgleish]

On 27 Oct 2006 18:27:40 -0700, "DonMorrisey" >
wrote:

>Hello folks. My kitplane manufacturer is ready to fabricate my engine
>mount and the Lycoming O-235 I have chosen is near the weight limits
>that my plane can handle. I am trying to find the answers to two
>questions:
>
>1. The distance needed between the mags and the firewall to be able to
>remove the mags for service without having to remove the engine?
>
>2. The published length, by Lycoming, of the O-235 is 29.05 inches.
>I have been trying to locate a dimensioned drawing to verify if this
>measurement includes the mags. Does anyone know where to locate such a
>drawing or know how else I can verify that information?
>
>Thanks. Don...
>
1 if you want to keep the engine as tight to the firewall as possible
consider getting them to make a swing-out mount
2 go to the airport and measure some engines. What you really need to
know is how far it sticks back from the mounting bosses.

[J. Severyn]

"DonMorrisey" > wrote in message
oups.com...
> Hello folks. My kitplane manufacturer is ready to fabricate my engine
> mount and the Lycoming O-235 I have chosen is near the weight limits
> that my plane can handle. I am trying to find the answers to two
> questions:
>
> 1. The distance needed between the mags and the firewall to be able to
> remove the mags for service without having to remove the engine?
>
> 2. The published length, by Lycoming, of the O-235 is 29.05 inches.
> I have been trying to locate a dimensioned drawing to verify if this
> measurement includes the mags. Does anyone know where to locate such a
> drawing or know how else I can verify that information?
>
> Thanks. Don...
>
I can go make some measurements, but on my 152, the real problem is removing
the oil filter. The full length 48110 filter just barely clears the
firewall as it is spun off. The newer 48110-1 which is slightly shorter
helps give added clearance. Of course if you do not have the oil filter
mounted on the rear engine pad, or no filter, (or a recessed tunnel for the
oil filter) then mag removal is the next concern. The 29.05 inches sounds
like it may be from the front of the engine case. What reference point do
you use?
Regards,
John Severyn
@KLVK

[J. Severyn]

"DonMorrisey" > wrote in message
oups.com...
> Hello folks. My kitplane manufacturer is ready to fabricate my engine
> mount and the Lycoming O-235 I have chosen is near the weight limits
> that my plane can handle. I am trying to find the answers to two
> questions:
>
> 1. The distance needed between the mags and the firewall to be able to
> remove the mags for service without having to remove the engine?
>
> 2. The published length, by Lycoming, of the O-235 is 29.05 inches.
> I have been trying to locate a dimensioned drawing to verify if this
> measurement includes the mags. Does anyone know where to locate such a
> drawing or know how else I can verify that information?
>
> Thanks. Don...
>

Don,
My previous message was not clear in regard to engine length.

What dimensions do you need? i.e. How do you want to define engine length
and what is included? What points on the front and the rear of the engine
are used for the "engine length".

After further thought, the front of the "support assy" for the starter ring
gear is probably the "front" (LW-13675 or LW-16577). But the prop flange
bushings (60814 and 73757) actually extend forward, slightly beyond the
"starter ring gear support assy".

The rear accessory case (LW-16011) has many pads that could be used as the
measurement point, but from the Lyc Direct Drive OH manual it looks like the
oil filter pad extends the most. However there are studs to other pads on
the accessory case that extend to the rear beyond the oil filter pad.

I have an OH manual, but no dimensioned drawings. However I can go measure
an L2C on a 152 if it helps.

Regards,
John Severyn

[DonMorrisey]

Hi John and thanks for helping.

I'm not sure what the refernce points are. The 29.05 inches is what
Lycoming publishes as the length and I'm not sure what their reference
points are. I believe it may be as the engine was presented for its
type certificate. Hence my desire to find a dimensioned drawing so I
could actually see. Right now I plan to remotely mount the oil filter
somewhere on the firewall if possible. If not I would get an adapter
which allows the filter to be attached at an angle. By looking at
photos it seems to me that the furthest point back is the firewall side
of the mags. I'm not sure that is a correct assumption. My engine
mount fabricator indicates that if I have 2.5 inches between the mags
and the firewall I will be able to get them off. I just want to be
sure.

I really don't want to do a swinging mount either. It just complicates
things and the cowl would have to come off to service.

Do you have a dynafocal or conical mount? If dynafocal could you
measure from the rearmost attachment point to the back of the mag or
whatever is the most rearward component of the engine, except the oil
filter?

Thanks. Don...

[J. Severyn]

Don,
The 152 has a dynafocal mount.
I'll make some measurements tomorrow per your requests, and try to pinpoint
the Lyc 29.05 number.

Is your return address valid? If so I'll mail some photos which might be of
help. I took some photos a few years ago during the annual inspection and
can take more if needed.

You can email me off-newsgroup if desired. Just cutout the ".cutout" from
my email address. Let me know if you have something other than dial-up
speed on your account, as the photos will be large. If you only have
dial-up I will reduce the photos pixel count. Or I can post them on the
'alt.binaries.pictures.aviation' if that is available to you.

More tomorrow.
John Severyn
@KLVK Livermore, Ca.


"DonMorrisey" > wrote in message
ups.com...
> Hi John and thanks for helping.
>
> I'm not sure what the refernce points are. The 29.05 inches is what
> Lycoming publishes as the length and I'm not sure what their reference
> points are. I believe it may be as the engine was presented for its
> type certificate. Hence my desire to find a dimensioned drawing so I
> could actually see. Right now I plan to remotely mount the oil filter
> somewhere on the firewall if possible. If not I would get an adapter
> which allows the filter to be attached at an angle. By looking at
> photos it seems to me that the furthest point back is the firewall side
> of the mags. I'm not sure that is a correct assumption. My engine
> mount fabricator indicates that if I have 2.5 inches between the mags
> and the firewall I will be able to get them off. I just want to be
> sure.
>
> I really don't want to do a swinging mount either. It just complicates
> things and the cowl would have to come off to service.
>
> Do you have a dynafocal or conical mount? If dynafocal could you
> measure from the rearmost attachment point to the back of the mag or
> whatever is the most rearward component of the engine, except the oil
> filter?
>
> Thanks. Don...
>