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Backcountry Pilot • 337 for Manual Flaps on a '66 Cessna 172

337 for Manual Flaps on a '66 Cessna 172

Have you modified your aircraft? STC? STOL Kit? Major rebuild from just a data plate?
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337 for Manual Flaps on a '66 Cessna 172

Before I go into too much detail, the motivation for this swap from electric to manual flaps is in part due to my lack of pilot ability and experience. I can list off all the practical reasons why I think manual is better, but its not important.

A few months ago, I bought a '66 Cessna 172G with an Avcon Lyc 180hp conversion. It's got the Hartzal 80" float plane prop (yes, its a float plane). The previous owner took great care of the plane and made tons of upgrades, including a Sportsman STOL kit, bubble windows, Landis gear, double puck brakes, etc. Basically, its a bush plane in great shape.

After a rough crosswind landing on a narrow runway, I decided reaching across the panel to hold up a flap switch is not fun. I found that almost no one has swapped to manual flaps. Actually, I only found one. A pilot/A&P/IA did it and actually got a field approval in 1993. I'm having my mechanic start the paperwork for my plane right now. My local FSDO said that they think it'll likely be approved in-house. Its all factory parts with no modifications AND there is a previous approval. No changes to the POH, Continued Air Worthiness, or placards are needed. It is considered a Major Alteration because it is either a change to the wing or a change in control surfaces, I cant remember which.

Basically, find all of the factory Cessna parts from a 63 and older plane. Its a DIRECT BOLT-IN to my '66 G model. I can't speak for other years/models, but the guy who did it last used a later H model with no problems.

I'll try to post good pictures of the swap. A local shop here has a complete '63 172 with all the parts that I need. I've already pulled most everything out. I'll get pictures on the way back in to my plane.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Contact BCP member 182 STOL Driver. He has a friend in Vegas who was involved in converting electric flap 150's to manual flaps, and they were also talking about doing 172's.
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Re: 337 for Manual Flaps on a '66 Cessna 172

I have manual flaps (63 P172D with an Avcon 180hp Lycoming conversion), and I like them--but they are no substitute for learning better pilot technique. I don't mean to sound arrogant, but how you dump the flaps in a 172 is much less important than whether you use them at all and if so how much, in a crosswind situation. In fact, if your only issue is having to hold the flap switch up, you'd be miles ahead dollar-wise changing just the flap switch to a later model which stays up when you move it up from neutral.

I don't recall which years for each change, but when Cessna first went to electric flaps in the 172 in 1964, the switch was spring loaded both directions, so that you have to hold it to keep the flaps moving either direction--like yours. That was later changed to one which is spring loaded only in the down direction, but if you flip the switch up, it stays up--I think that was roughly in 1969 or 70. That was later changed to what some call the pre-select switch with notches on the panel, where you move the switch to the flap position you want, and the flaps move to that position--late 70s I think.

I think you'll spend lots and lots of money on the change-over to manual flaps which could be better spent on 100LL and crosswind training. This comes from someone who has spent lots and lots of money on his own airplane which others would say was maybe foolishly spent, but then it's my airplane--so if you want to spend it, that's your business. But also learn how to handle crosswinds, because manual flaps won't do that for you.

The technique I was taught for extreme crosswinds, and which I later taught when I was instructing, was not to use flaps at all, or if carrying a full gross load, use only 10 flaps at most. I hadn't learned crosswinds well in my primary instruction because there was so little wind in the Anchorage area while I was learning--my crosswind technique sucked. But when I left the USAF, I moved to Laramie, where crosswinds are a way of life. The day I really learned crosswinds, my instructor called to say that the day was perfect--winds straight down 21 at 25G30--but we would be using 30-12. The airplane was a 1970 172. After half a dozen landings in each direction, I had learned how to handle extreme crosswinds, crosswinds which require full rudder and a whole lot of effort--but no or very little flaps.

If you haven't already flown a Cessna with manual flaps, you'll find that to apply the first 10 flaps from zero, you'll need to lean down far enough that you can't see over the panel--that's where our friend EZ Flap's mod comes into play. Depending on your size (mostly on your arm's length), from 10 on to 40 isn't a problem, although the last 10 are a bit of a tug. Dumping the flaps after landing (unless you add EZ's mod) is best left to 10, again because you'll lose sight of the runway if you try to put the handle down all the way. Consequently, I rarely retract the flaps all the way until I've left the runway.

Just my thoughts.

Cary
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Re: 337 for Manual Flaps on a '66 Cessna 172

There is one in Juneau. It was an air taxi machine for awhile, meaning the paperwork is done. It also has all of the co-pilot controls permanently removed and a very customized panel/glare shield. It is totally stripped down, really performs well.

I understand the manual flap conversion was a total nightmare. The fellow that owned and built it up was an amazing wrench as I understand it. One would really have to be in love with the airplane to even consider doing it and have the ability to do the work themselves. Hardly seems worth the effort, but to each their own.

I can put you in touch with the current owner if you'd like. He is a super nice guy and I am sure he'd help you out with paperwork.

Edit:

I didn't read your post fully. We are probably talking about the same airplane.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Cary, I can't argue with you one bit. My runway at my cabin is a crosswind runway. Its inevitable. After having tons of hours in both 180/185 on wheels and floats, I just prefer the manual flaps. I have "muscle memory" that I have to change with my 172. I'd be a fool to say that I can't use more training (no matter how much time/experience I may have). You don't sound arrogant and I appreciate the advise.

The removal of parts took about 2 hours last night. I'll spend about $1.25/foot for SS cables. McFarlane Aviation has new pulleys, which I don't think I need. I got all of the parts for free since the fuselage is on its way to the recycle depot soon. I expect to have about 8 hours installing the parts, rigging the flaps, and checking function. That's the plan (a plan is just a list of things that won't happen). When Cessna switched from the manual to the electric, the made no changes to the fuselage. When I opened up my plane, all of the holes and provisions are already there, like the other plane that was changed.

If all goes well, I'll have a few hundred dollars and a full weekend into the swap. I think that the manual flaps will be better for flying floats and short runways. I cannot find anything of just changing the switch. If you can point me in the right direction, I'd be interested in finding out.


gbflyer, I may take you up on that. I'm supposed to meet the new owner of the plane still here in Fairbanks. I'll be able to actually look at the plane and make sure that its as easy as I thought.


EZFlap, I know that there is an STC for the Cessna 150s. As I understood it, it required special (non-Cessna) parts and Fuselage modifications. I do know that the Cessna 150 parts are different. Cessna 172-185 all share the same part numbers according to a Cessna parts catalog that I'm using.
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Re: 337 for Manual Flaps on a '66 Cessna 172

I have worked on a 170 that has a set of electric172 wings on it converted to manual. Still had the brackets and extra inspection plates for the electric motor in the right wing. Since there is already an approved 337 for what you want to do then going the follow on approval route is pretty straight forward...... I say go for it, but I prefer manual flaps also...

Brian
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Re: 337 for Manual Flaps on a '66 Cessna 172

How about getting a 337 on a yoke mounted EL, flap rocker SW? I have often thought about how handy it could be in the left side of the yoke or even on the throtle knob.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Cary wrote:I don't recall which years for each change, but when Cessna first went to electric flaps in the 172 in 1964, the switch was spring loaded both directions, so that you have to hold it to keep the flaps moving either direction--like yours. That was later changed to one which is spring loaded only in the down direction, but if you flip the switch up, it stays up--I think that was roughly in 1969 or 70. That was later changed to what some call the pre-select switch with notches on the panel, where you move the switch to the flap position you want, and the flaps move to that position--late 70s I think.
Cary


I have been flying a rented '69 C172K and it has the spring loaded flaps as well. Its something I hate being a new "almost pilot" (checkride next week). Obviously, the more experienced you are the better you can handle reaching over to lift and hold, however seems like a needless safety hazard to have to take your eyes off needed instruments or runway to look for the switch...sometimes more than once depending on turbulence. Also, the electronic flaps are so god awful slow.

When I buy an airplane, I'll be looking for manual flaps.
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Re: 337 for Manual Flaps on a '66 Cessna 172

I have the drawings of all the parts - could be done for about 2 grand we were working on STC but run out of money - so they did 3 on field approval with DAR signing off .
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Re: 337 for Manual Flaps on a '66 Cessna 172

Not quite as good as a johnson bar, but it sounds like just relocating the flap switch would go a long way toward improving things, and be a helluva lot less work.
FWIW I think Mike Sibley in Kenai has converted some C150/150TD's from electric flaps to manual.
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Re: 337 for Manual Flaps on a '66 Cessna 172

172heavy wrote:How about getting a 337 on a yoke mounted EL, flap rocker SW? I have often thought about how handy it could be in the left side of the yoke or even on the throtle knob.


As mentioned, that would certainly be an improvement, but IMHO not a big improvement. The major advantages of manual flaps (Instant actuation, reduction in complexity, less failure points) would not be addressed by moving the flap switch.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Sorry this died for a while. I was granted a field approval a while back. I pulled all the parts from a 59 Cessna 172. I grabbed every part of the flap system.

In my plane, all of the appropriate holes are in the bulkheads were present; all I needed to do was bolt it in the pullies/brackets. The total cost in parts (including pulleys) was approximately $400.00. I was able to get most of it used and had to pull it myself. It turns out that some of the brackets and pulleys were already installed in my plane. The hardest part was to locate the manual flap bell cranks. I found three sets here locally for a good price.

I know that 172 through 172 H are all on the same type certificate. Since there were no changes to my owner's manual" or placards, it was really easy to get. I paid a local mechanic to get the 337. I know that I have the second plane that got approved. The other is still up here flying around. The STC seems like it'd be easy to get (relatively anyway). I have all of the Cessna part numbers for anyone interested.
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Re: 337 for Manual Flaps on a '66 Cessna 172

That flap switch sucks, I've put about 600 hours on mine and it's just as funky as the first day. I've learned how to deal with it, mostly by not mucking with it on the ground roll, but I'd like to see that parts list in case it's the same for a skylane. Sent you a pm. Posting the list with this thread would be handy too.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Nkldrgr wrote:I know that 172 through 172 H are all on the same type certificate. Since there were no changes to my owner's manual" or placards, it was really easy to get. I paid a local mechanic to get the 337. I know that I have the second plane that got approved. The other is still up here flying around. The STC seems like it'd be easy to get (relatively anyway). I have all of the Cessna part numbers for anyone interested.


I Have reims cessna f172h -68 taildragger (Made in France) and Im not fappy with flaps switch. my friend has c170b of course with manual flaps. Its fast and easy to operate. Do you have photos or any documents for this modification?
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Re: 337 for Manual Flaps on a '66 Cessna 172

Nkldrgr wrote:Sorry this died for a while. I was granted a field approval a while back. I pulled all the parts from a 59 Cessna 172. I grabbed every part of the flap system.

In my plane, all of the appropriate holes are in the bulkheads were present; all I needed to do was bolt it in the pullies/brackets. The total cost in parts (including pulleys) was approximately $400.00. I was able to get most of it used and had to pull it myself. It turns out that some of the brackets and pulleys were already installed in my plane. The hardest part was to locate the manual flap bell cranks. I found three sets here locally for a good price.

I know that 172 through 172 H are all on the same type certificate. Since there were no changes to my owner's manual" or placards, it was really easy to get. I paid a local mechanic to get the 337. I know that I have the second plane that got approved. The other is still up here flying around. The STC seems like it'd be easy to get (relatively anyway). I have all of the Cessna part numbers for anyone interested.


This thread was resurrected just in time. I'm considering the same thing, do you still have the parts list handy?
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Re: 337 for Manual Flaps on a '66 Cessna 172

Cary wrote:
I don't recall which years for each change, but when Cessna first went to electric flaps in the 172 in 1964, the switch was spring loaded both directions, so that you have to hold it to keep the flaps moving either direction--like yours. That was later changed to one which is spring loaded only in the down direction, but if you flip the switch up, it stays up--I think that was roughly in 1969 or 70. That was later changed to what some call the pre-select switch with notches on the panel, where you move the switch to the flap position you want, and the flaps move to that position--late 70s I think.

Cary


This quote was in a response years ago on this thread. It is as it appeared, with no reference where it came from or when Cary posted it.

----------

I have a C172E. FWIW, the aircraft has manual flaps and stops fot 10, 20, 30, and 40 degrees.

I agree with Cary's obsevation in yet another quote on this thread that it's technique and sight picture that matters, not whether the flap system is electric or manual. FWIW,I carry a small amount of power into the flare whether with or without flaps.
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Re: 337 for Manual Flaps on a '66 Cessna 172

Following your post about converting c-172 electric flaps to manual flap system.
I have a 172-H I want to convert to manual. We’re you able to get the STC? If not, do you have a 337 application /approval that I could access?
In STL. The local FSDO are sticklers.
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Re: 337 for Manual Flaps on a '66 Cessna 172

I also have a C-172H. I want to convert to manual flaps. Would you be willing to provide the data you used for the 337 application/ approval?
Thanks!

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Re: 337 for Manual Flaps on a '66 Cessna 172

This does not reference your post directly, but an experience I had. Years ago I was configured for landing in a 1963 manual flap 172 which at the time I had about 3,000 hrs. in. The runway set on a high hill with substantial drop off on the approach end, the wind was gusting 30 plus, I had 40 degrees of flap which is normal for me. On very short final the sink rate increased to more than full power could handle, I retracted all the flaps instantly or would have impacted the side hill. Manual Flaps saved me. In retrospect I should have known there would have been a strong down wash in that environment.
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Re: 337 for Manual Flaps on a '66 Cessna 172

We’ll, I must be a real retard.

I worked (and owned) manual flap equipped Cessnas for decades.

Started flying a 206 at work, mostly off airport, and I fell in love with those electric flaps. My current early 175 has manual flaps. I don’t hate them, but I’d happily fly a plane with electric flaps.

Indeed, however, the later switch where you just put the switch where you want the flaps is a LOT better than the “hold it till it’s done” type switch.

But, if it makes you happy, enjoy.

I much prefer not to reach way down to grab flaps initially. Apparently not ape-like enough…..

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