modify 172M flaps

modify 172M flaps

I own a 1973 172M model.  I would like to change the flaps system to a 30/40 degrees NOTCH system instead of the cuttent gauge system.
Is this possible? and what parts would I need to replace?

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Re: modify 172M flaps

Major alteration, affecting flight controls AND aerodynamics of the aircraft. Contact a DER with structures & aerodynamic ratings, and bring your checkbook.

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Re: modify 172M flaps

Charles wrote:

>Major alteration, affecting flight controls AND aerodynamics of the >aircraft. Contact a DER with structures & aerodynamic ratings, and >bring your checkbook.

Why is this a major alteration, Charles?  Why would changing the type of flap switch affect the flight controls & aerodynamics?

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Re: modify 172M flaps

There has to be a flap follow up cable, cam, microswitches, and associated wiring added to the flap control. The follow up cable has to be tied into the flap extend/retract cables. I'm pretty sure there's some structure under the panel that must be changed, as well.

Generally speaking, adding wiring or circuitry, switches, ect moves you into "major Alteration" territory. 

This aircraft has an FAA approved POH. Any change to the operation of a flight control, and flaps are a secondary flight control, will require an FAA approved revision to the POH. This approval will almost certainly require flight testing. Doesn't matter to the Government that the flaps travel the same 40 degrees down or not.

A "maintenance manual" for the system, approved for this one airplane must be developed. You can't just say "look at the C172N maintenance manual" and expect a field approval.

Not saying it can't be done, but a field approved 337 will be a 50 page paperwork package. The new field approval process requires many hoops to be jumped through, including a 14 CFR reference for everything.here's a link:

http://www.google.com/url?sa=t&sour … zrC_drPJxQ

You might try looking at the parts book. Cessna had a way of sort of gradually blending changes into production, thus a late-in-the-year 172M might, just maybe, have come with a pre select system. That would give you a 'cover story' anyway, if you were to install the system without 337 approval.

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Re: modify 172M flaps

Thanks for the input and explanation.
Based on this, I will have to learn how to live with these flaps...

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Re: modify 172M flaps

Yes, thanks, Charles.

Didn't know how complicated it was to do something that seems so 'simple."

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Re: modify 172M flaps

Did You consider the digital flap gauge as a viable alternative. I did and I really like it. The price is reasonable also.

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Re: modify 172M flaps

This is something I did not look into.
Can you give me more details.

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Re: modify 172M flaps

You get a new sending unit and digital flap gauge, use the existing wiring, so it's pretty much having your mechanic swap out the old parts. The switch itself remains the original but the gauge is way easier to read even with a brief scan or the momentary flap actuation and it indicates flaps by 5 degree incriments. By visual instruments (visualinstruments.com) - looks like the going price is $495.00. I think thru 15 degrees is green and 20 thru full flaps shows up orange.

The addition ot the new flap sender and gauge corrected one of the major problems I had with my 172K when I first bought it. I never liked the original from the start and in my 172 it was close to worthless on actual flap setting - sort of gave me a general idea after 5 minutes or so but was really of no real help when you needed it or were real busy. The "old" advice was to look (to the side ) out the window, or count which was more accurate than the old flap gauge, but the new gauge is easy to read even with a very brief scan and the flap position is quite accurate.

I would do the flap sender and indicator again in an instant, I wouldn't do their volt meter again tho.

I did add a digital fuel (and also an engine oil temp-press gauge) that I also really like, with a similar readout, from another vendor, which is very accurate, so I can actually tell how much gas I have through the entire range, instead of rocking the wings or guessing. I can tell exactly where these gauges are with a very brief scan, and it's hard to miss the readings even if you're not really looking for them.

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Re: modify 172M flaps

Thanks for the info.
It looks very promissing, and I will look into this.

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Re: modify 172M flaps

I am assuming your plane has electric flaps but it just has the switch not the notch flap handle. 
I am not sure but I think Cessna has a retrofit kit for the electric flaps to ad the notch flap feature.  I know there is one for the Cessna 150.  My 150G model has a notch flap kit available directly from cessna.  Hold your wallet tight!  The fast vacuume force from Cessna will... But when I went to cessna to order a new flap switch it crossed over the switch in the parts manual at the Cessna dealer.  It says something like when supplies are exhausted install this kit PN:??? The kit does come with a supliment for the POH. 

Please post here if you find the kit.  If you do not have a local cessna dealer I can check for you at my local dealer but it may be a couple of weeks befor I can get over there. 

This e-mail address is being protected from spambots. You need JavaScript enabled to view it
 

RonB Wrote:
-------------------------------------------------------
> I own a 1973 172M model.  I would like to change
> the flaps system to a 30/40 degrees NOTCH system
> instead of the cuttent gauge system.
> Is this possible? and what parts would I need to
> replace?

jeffrey.puckett
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Re: modify 172M flaps

Hi,

My supplier does not know anythig about a kit for this.  So if you can re-check with your supplier, it will be great.
Thanks.
Ron

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Re: modify 172M flaps

Will try and look it up this week, perhaps it is no longer available.

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Re: modify 172M flaps

OK, I found my notes, and I remembered incorrectly, it is not for a Cessna.  I getting old and I remembered wrong.  Please accept my appologies, I was wrong.  There are issues with the 30 verses 40 degree flaps and a considerable amount of complex hardware and wiring.  So Your friend was correct, there is no kit for a Cessna electric flap position indicator / actuator conversion. 

Jeff

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Re: modify 172M flaps

Hi Jeff,

Unfortnatly I had a problem with my mil system and lost the all the info you sent me (together with your e-mail...).

May I ask you to re-send.

Thanks,


Ron

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