170 versas 172 cowlings

[butchpilot170]

Hi again ! Anybody know if I can convert my '56 172 top and bottom cowlings to the latch type of the 170's ? It would sure make doing pre flight checks better !

[bagarre]

Hi again ! Anybody know if I can convert my '56 172 top and bottom cowlings to the latch type of the 170's ? It would sure make doing pre flight checks better !

It would certainly fit - you'd just need permission from the big guy.

[Bruce Fenstermacher]

Butch, you have an A model which has the early cowl, or should have the early cowl. This is not a pressure cowl but the pressure baffling is inside of the outer cowl. The complete upper left hand and right hand open. This is NOTHING like the '56 cowl.

Could the '56 cowling as a whole be made to work? Sure. Remove the inner pressure cowl and install the later rear and cylinder baffling that seals against it. Legalities of course we haven't discussed.

I'd rather have the '52 and earlier cowl myself.

[c170b53]

Butch thanks for the questions ( challenges ). It could be me but if you elaborate a bit more in the question as in give us an idea of your end game that might give you a better solution.
So you want to mod your 172 cowl because ? . The 170B would have an almost identical cowl to the 172. The front nose bowls are often cracked on those models so if yours isn't you'll want to leave it be. Some originals guys will likely slobber all over it.
The 170A top cowl has two side panels that open up and a fixed center panel some like it more than the B but you probably know this. My 53 B had two doors attached to the bottom cowl, latched by the top cowl, so they really are a set. When it comes to maintenance, for me, most of the time regardless of the model, you're takin them off.
The B- 172 top cowl has a compound curve combined with a slant. Tough job to duplicate also some interior pieces are spot welded to the cowl, again hard to fabricate from scratch.
170 A might be easier to make because the top is three pieces ( as are all bottoms cowls) plus the nose bowls.
I think Bruce nailed it, it's a matter of what you can do versus what can you do ala stealth or whether you stay legit. Some can be successful going rogue but you have to know exactly what your getting involved with. Think of the engineering to make the plane, test it and then make adjustments for the final product. Often that process and the trials undertaken by Cessna might not be obvious, but they knew what they were doing.
If you're new to wrenching, think a few times before you act and get dirty. The outcome may be more to your liking and I've used that approach because it works and there's the little matter Of boosting the O.T. bank.....how's that for just saying Think I might need to don my hazmat suit

[butchpilot170]

Thx guys ! It's just that during my 45 years of flying I have always done a good pre flight before leaving earth . Cessna 140's, 170's Tripacers, Pacers , Stinsons were all preflightable (my new word ) nicely because of the "doors " . You never know what's not right under the hood and I know I'll be happier with my new 170A than my '56 172 when it comes to that ! Butch !

[Bruce Fenstermacher]

You never know what's not right under the hood and I know I'll be happier with my new 170A than my '56 172 when it comes to that ! Butch !

Yes in the preflight department you most likely would like the '52 and prior cowl over the '56.

However there are some issues with the early cowl. First and for most, you must add some type of positive locking mechanism to the latches to insure it does not pop off in flight allowing the cowl to open. This event will, at the least, damage your cowl and stain your paints. My 170 was ground looped by a previous owner ripping the landing gear from the fuselage on an expedited landing gone wrong due to the cowl flying open. There are several schemes to accomplish this easily. I do not consider a 170 with the early cowl without such locks on the latches, airworthy.

The next thing you might not like about the early cowl is if you install a later bullet style spinner. It can be difficult if not impossible to remove the 4 cowl screws behind the spinner to remove the upper or lower cowling.

[Watkinsnv]

My 52 170B has a later 172 cowl I had approved to install when I converted to the Del-Air Lyc O-360 which also has a different nose bowl. I like it

[170C]

As you likely are aware, the B model 170's, excluding the '56 model had two doors on the upper cowl (one on each side) which gives good access to the engine compartment. '56 170's & 56-59 172's only have one (left hand side) doors. If one were to want to spend the time, $$ & the paperwork you could add a right hand door to a 56 cowling. My 56 172 has only the left hand door and while it would be nice to have the right hand door, I have never had any issues not having it in 27 yrs of operating it. Just depends on what you feel you need/ want/can afford, etc.

[GAHorn]

Hi again ! Anybody know if I can convert my '56 172 top and bottom cowlings to the latch type of the 170's ? It would sure make doing pre flight checks better !

I think I read your question a bit differently. You want to convert your later cowl to an earlier type to facilitate an easier pre-flight of your engine compartment.

This would be a really, really, REALLY difficult thing to do. Firstly, as Bruce mentioned, your engine cooling would be an entire different added problem.
Secondly, your nose-bowl would then be unsupported and eventually disintegrate without heavy modification.
In short, the answer is NO.

But did you know you can remove your upper cowl without removing the lower cowl? And it's only a portable screwdriver and a handful of screws? It takes about 3 or 4 minutes.
But WHY? All you need do is look into the front with a flashlight, open the cowl door to check the accessory case and check the oil.
There's no advantage whatsoever to the early cowl when checking the lower engine area.
And those latches you think you want?... did you know a set of them cost almost $1K...??? And when they wear out they are difficult to keep closed?

The later cowl was a vast improvement over the early cowl. That's why Cessna never went back to the early cowl.

[butchpilot170]

I'm sorry , with due respect , I have always wanted to check as much as I can on what is going on FWF before I take flight . Possibly exhaust manif. leaks , push rod seals, loose bolts, clamps , etc. The "door" system I think is co much better ! I go to the airport to fly but I don't want to be thinking if everything is ok when in flight because I didn't spend time taking off the top cowling and check things . the ButchPilot !

[GAHorn]

OK. So you open the door and look inside for all those things...and see...less than this ...(because unlike this pic, the lower cowl will still be attached):

170ABox.png (32.7 KiB) Viewed 17158 times

How much of the things you just listed are visible?

[Bruce Fenstermacher]

George, there is no question, it is easier to view more of the engine with the earlier cowl vs later specially by '56, however it is not panacea. Yes, you can see exhaust manifold leaks easier. And yes, if you own a 170 exhaust it is a matter of how much the exhaust leaks. You can't really see push rod tubes that well.

Want to inspect an engine compartment or any compartment thoroughly on preflight, get a Cub.

[c170b53]

Oh that hurts...

[Bruce Fenstermacher]

I was not suggesting people shouldn't want to inspect the engine compartment. I was pointing out you can't beat a Cub for being able to do so easily.

[GAHorn]

Bruce, surely you're not trying to teach me what is under the hood of a 170 cowling.

The point I was hoping to bring home to Butch is that the cowling conversion he imagines is not that advantageous over the later cowl for inspection purposes....particularly with respect to the trouble, cost, and certification issues he probably didn't foresee.

EITHER set-up can be inspected by sitting on the ground with a flashlight and peering up the cowl-lower-exits.
A flashlight and a mirror can go a long way to a preflight inspection. And we all know that an oil leak on a O300 is not difficult to detect.
In the case of such findings,...the cowl on BOTH TYPES will have to be removed to properly address the issue, ...and the aforementioned troubled
cowling conversion will not be seen to have been particularly helpful and certainly not frugal.

Butch, with a fat wallet, anything is possible. If you go for it..... Write up an article for the 170 News. I'll pose for a pic with a spoonful of crow.