Cowl cover, Duct tape, and Winterization; Adjust. cowl flap

mjgardne · Post by **mjgardne** » Mon Feb 03, 2003 8:40 am

Hi Everyone,

Winter has been very mild in Fairbanks this year, and all I have been doing to keep the engine warm is to put some duct tape over the oil pan opening on the cowl. This has given me adequate operational temps, but... I decided to top the engine, and need to have some extra warmth for the first few hours on the new cylinders. My mechanic has suggested a single piece of duct tape placed vertically in the middle of the cowl openings behind the prop. The idea is to have the air burbble to avoid a hotspot, while restricting the airflow a little. He said I should shoot for 180F temperatures for several of the break-in hours. Any comments about whether this placement will work, alternative ideas, and whether it will cause damage would be greatly appreciated.

On another note... I saw a C170 here in Fairbanks with an adjustable cowl flap! I am thinking about copying his design and applying it to my airplane this summer. Have any of you seen this done to a C170? Any comments? The owner said he had to reinforce the clamps that keep the cowl access doors closed because of the back-pressure, but it has been working well, and the FAA wrote it off.

Thanks in advance,

Mike

Post by **Bruce Fenstermacher** » Mon Feb 03, 2003 1:43 pm

The amount of tape required will depend on outside air temperature. I'm in Pa where it is usually between 20 and 30F in the winter. I have the early cowl with the horizontal ribs. Below about 40f I cover the oil pan opening only. About 30f I cover the top slot on each side of the cowl with duct tap. Below 30 I cover the second slot fronm the bottom also. This leaves 2 horizontal slots open. These mods usually give me oil temps between 180 and 200f.
This year I covered the top slot then put a single piece of duct tape vertically top to bottom in the center of the opening with the same results.
You will have to experiment. Put one across the top and cover the oil pan. Go around the patch. If it's not hot enough, land and add more.
Make sure you use that special PMA/FAA duct tape

My tape lasts a whole season and is a pain to get off in the spring. Be careful you don't lift any paint on removal. Been there done that.

zero.one.victor · Post by **zero.one.victor** » Mon Feb 03, 2003 5:09 pm

I wonder if the blue masking tape used by painters would hold up for airplane use? It's made to come off without goofing up the paint job underneath.
I think the factory put out a winterization kit at one time that covered about 1/2 of the openings on either side of the prop. I believe it was for the early (48-52) cowl nosebowl,and covered the outboard half of each opening. There was a drawing in the #1/96 170 News of a similar homemade part,as submitted by member at Bartone. He makes a reference to Cessna p/n 0552101.
I've heard of a few 170's with controllable cowl flaps,seems like it was always on a big-engine conversion. Don't know anything about the approval of such a mod.

Eric

Mon Feb 03, 2003 10:45 pm

cessna did make a winterization kit as you describe. Reason I don't cover the inboard half is that that would also block the air intake for the heater. I don't want to do anything to hurt the already dismal output of the heater.

JDH · Post by **JDH** » Mon Feb 03, 2003 10:48 pm

Duct tape works good. To take it off without leaving any trace or paint, take it off when the engine is warm (right after you've landed and parked); it'll come right off, like using heat gun or hair dryer to remove a sticker. If any residue, use WD40.
Eric, my '52 has a winter kit and the inboard (towards the prop) is what is blocked for the exception of a hole lined up with the blow tube on the pilot's side; also, an aluminum plate covers the oil pan square opening. By the way, we add a strip of tape next to the winter kit when temperatures go below -20Âº C; it happens that it gets below my limits (don't like to start her up below -15) after a winter camping outing or if we stay over longer than anticipated... JD

Post by **GAHorn** » Tue Feb 04, 2003 12:00 am

There is no need to artificially elevate temps during break-in. In fact, the cool temps are great for break-in. Just fly it at low altitude with open throttle for the first hour or two.
The winterization kit is illustrated in the SRAM or the 170 Book if I recall correctly, . (I'm not at home and do not have access to my resource manuals. Sorry.) and could be made in the field. If you insist on doing this, you probably should use one

n3833v · Post by **n3833v** » Tue Feb 04, 2003 4:33 pm

I close my oil pan opening with the side of a white oil container ribbed side. Make it oversize and cut slots as tabs on the end and slide the tab behind the cowel so that the main portion is outside and covered thus not having to pull paint with the tape. I am still looking for a good way for my 2 bar grill holes.
John-n3833v

zero.one.victor · Post by **zero.one.victor** » Tue Feb 04, 2003 5:36 pm

I made a little aluminum plate to cover the "oil cooler" on my ragwing. Put a tinnerman on each side of the opening & used machine screws. The cover & the tinnermans come off after winter's over,leaving only 2 small holes.
John,it shouldn't be too hard to build a pair of partial covers that clamp onto the bars of the nosebowl openings. Or maybe a piece of plastic from that same oil jug taped in place from behind. Don't know how well that would stay in place,but if the oil cooler cover you describe stays put then the tape trick might work.

Eric