The International Cessna^® 170 Association

Can anyone share experience / or recommendations on wether I should
consider switching from my original airbox style engine baffles , to the pressure cowl style ?

My A/C is a 1952 170B , sr 20292, my original baffles are in very poor condition and new ones will have to be frabricated , using the old ones as patterns , and I have inherted a good set of the newer style pressure cowl baffles. The only issue I can think of is that the upper cowl may not have enogh structure to handle the increased air pressure/loads.

John Atkins

That's exactly the problem. The early cowl was not desgined to contain the pressure cowl baffles and their increased air pressure. You'll also have a documentation issue. I'd recommend using your old parts to make new ones. Guess who's interested in getting set up to mfr them? Yep, the same folks who recently got PMA'd to do our steel axles and pressure cowl baffles, AirFrames, Inc. Contact them, and see if he won't use yours as a prototype.
Airframes, Inc.
P.O. Box 521795
Big Lake, AK 99652
PH: 907-892-8244
http://www.enginebaffles.com

Ok that is what I was afraid of ,
oh well more $ , but if it is worth doing ,...
do it right !

THANKS !!!!!

The early (48-52) cowl may not have been designed to be used as part of a pressure cowl arrangement, but that doesn't necesarily mean it wouildn't work. A friend of mine has a 52 with the Lycoming conversion and it is set up as a pressure cowl using the stock upper cowl assembly.
Anybody else using the early cowl as part of a pressure cowl set-up?

Eric

It would be nice to have a pressure cowl setup with the old hinged upper. I really like being able to look inside my cowl when I'm preflighting, my only complaint is that I can't see inside the pressure cowl without taking it apart. I had a little birds nest in there a while ago and didn't see it. I think it was only in there for one flight, because I did get a faint whiff of cooking grass on that one take-off (thought I was imagining things), then on the next preflight the birds had added some more grass and one little strand of green twig was sticking through the bottom of the pressure cowl. After I cleaned it up and sealed the intakes with duct tape the little buggers camped out on my prop and bleep all over my plane. It was like they were pissed for a day or so then moved on to the old Beechcraft down the way.

The original baffles on my 1951 170A with an O-300D were all shot when removed for the engine overhaul. My IA said he could make copies but they would be expensive. He told me about;

Airframes, Inc.
P.O. Box 521795
Big Lake, AK 99652
PH: 907-892-8244
http://www.supercubs.com NOT http://www.enginebaffles.com as previously mentioned

As George mentioned earlier, their catalog shows they are making baffles for the 170B only, BUT, they had made a special order partial set of 170A baffles for a customer and ran off 4 sets at the same time. They did not have the rear baffle pattern made. Mine was still in good enough shape so when I bought the other pieces they had on hand, I made a deal with them to reverse engineer the rear baffle off of mine. So in effect, they will have all the pieces required for the 170A system in a couple of weeks and they will use my installation for their conformity inspection to add the 170A to their approved list. Good news for those who want to keep their planes as original as possible. The whole set should come in around $1000. The parts are all on CAD and and look very professionally made. A few changes will have to be made to the 170B front baffles by the buyer but nothing serious and it all involves removing metal to fit your cowl.

Also, for those who want to convert to the pressure cowl, Airframes has a copy of a DER report on a one-time conversion and a 337 which was approved to do it. In effect, the report says it should work as good as it does on the 170B. The Dip Davis cowl latch replacement STC has to be used on the conversion possibly indicating the cowl latches might not be stout enough to take the pressure. Airframes, Inc has all the other parts to do the conversion although some might require modification.

Since it was available, I chose to go back original with the air box.
Richard Pulley

When I installed the Continental IO-360 in my '52 C-170B, there was no mention in the STC about any kind of a problem with the change to a pressure cowl using the stock '52 style hinged cowling. It works just fine. I know of a number of other aircraft that have done the same thing with conversions to any other engine. I have also seen it done on '52 model airplanes with stock engines because of deteriorated plenum boxes and baffling.

Airframes, Inc., 907-892-8244, http://www.supercubs.com now has all the pieces required for the 170A system with the air box. They will be using my installation for their conformity inspection to add the 170A to their approved list. Good news for those who need airbox style baffle replacement. The whole set should come in around $1000. The parts are all on CAD and and look very professionally made.

They completed the last remaining part, the rear baffle, today. After a few adjustments to the baffle seals it looks great.

We'll see how well everything fits up when the engine overhaul is completed and all the baffling is back in place.
Richard

Replaced mine in my '56 172TW with Airframes Inc. Fit absolutely perfect. Excellent workmanship. Seals over-lap and fit snug. Very good quality. You'll be glad you bought them!

Post some pics next week!

Joe, your link takes us to a window that says, "You have attempted to hotlink to an image on myfamily.com. This operation is not allowed"

Thanks,
I'll remove it. Thought I'd post a pic, but didn't work. I'm at home now, and all my pics are in my computer at the office. I'll post next week!
We have a sight @ MyFamily.com called the KTAN users group. It's a great way to keep in touch and up to date with all the locals. Set one up for your field. Lots of laughs!

According to Aerospace Welding Inc., in Minneapolis...(the folks who donated an entire exhaust system to our Assoc'n this year in Kelowna)... They are now THE distributor for Airframes, Inc in the lower 48 states.
If you need baffles, you may contact them at:
http://www.awi-ami.com/
800-597-4315 Ask for Charlie Fields or Tom High and tell him the 170 Assoc'n sent you.
George Horn