Insulation in the rear air inlet housing, or wing to fuselage cavity?
 

Have any of you seen, or have, fiberglass insulation around the rear engine air inlet?

How about in the space between the both wings and the fuselage under the fairing strip?

I have fiberglass insulation in those three locations. I don’t see the use for it and can see no reference for it in the parts manual. I think it could retain moisture and could generally be detrimental.

Should I remove it, or keep it?

Rick

Insulation
 

That’s weird. Mine doesn’t have it. I couldn’t see the value either.

Scott

Never seen that in any of the three P337's I have owned including a Reims built aircraft. Not sure what the purpose would be.

I have the insulation in mine, the aircraft used to have the JB air conditioning system, don’t know if that has any usefulness.
Dan
P337-0168
N67S

My thought is the insulation in the rear inlet is to prevent oil canning. One of our Skymasters was missing it and popped a bunch of rivets on the top skin. All Cessna singles I’ve worked on over the years have had insulation in the armpits

Thank you for the input guys, now to figure out the best thing to do ... :confused:

Rick

My Riley P337 doesn't have it in any of the places you mention.
I can't think why you would put insulation there?

Thanks Chris,

I think we’re going to remove it.

The only reason I can see to keep it could be the prevention of oil canning that Kim mentioned below. I think it would take a lot of insulation to be crammed in there to apply enough pressure against the air inlet that it’s unlikely to have much effect.

I’ll monitor the rivets for paint cracking and report back if I see anything detrimental.

Rick

I took every fragment of fiberglass insulation out of my plane and replaced it with STC'd foam aviation product. Didn't use any outside the cabin. Get that old fiber filter out and put in the garbage, it's useless

Thanks Herb. Do you recall the name of the foam you used and where you got it from?

Rick

I found the same in my rear engine intake, stuffed into each side. The aircraft had been in a hangar for a month and it was still damp. Yanked it out quickly…doesn’t seem to be any point other than to keep birds from building nests.

Agreed, thanks for voicing your experience,

Rick