Cessna 170B wing replacement.

[bensmotorworks]

attatched is the letter from CESSNA.

[Bruce Fenstermacher]

Ben, you have a 2017 copy of the same letter issued to my first 170 dated 2001 which is in our library.

The process is 2001 was, based on the letter, a person would find suitable wings. Once found and the part numbers given to Cessna, Cessna would then issue a letter stating the specific wings would be suitable replacements. That last letter was then used to gain FAA approval on a 337. None of Cessna's letters by themselves where approval.

In my 170A case the second letter was never sought from Cessna but the letter used to gain approval for what was thought to be Cessna 170B wings previously installed and not documented. The wings turned out to be L-19 wings with 170B tanks and flaps.

In about 2004 I talked to the Cessna rep at the time who authorized the letter I had. He said the wings didn't need to be a perfect match so long as they could be modified to match ie tanks, fuel gauge, flaps, manual flap driving mechanism. He was surprised to find out the FAA approved my wings just based on the first letter. BTW this was all done before I owned the plane.

This really is a no brainer but we know how the FAA is about such things. Good luck.

[bensmotorworks]

Thank you!! I will contact Cessna tomorrow and talk to the same guy I spoke with.
Ben

[bensmotorworks]

Well... I did a little more research. The plane I have is a Cessna 1955 170B SN26977 the donor plane is a 1956 Cessna 172 SN 28849. According to the parts catalogs P108-12 (Cessna 170B) the right wing is 0523005-1 The left wing for the 170B is PN 0523005 and in your online parts manual Temperary revision Number 1 page 2 item 1 it states that the part number goes from a 0523005 to a 0523005-58 and based on Cessna 172 manual P257-12 the right wing is also a 0523005-1 the left is 0523005-58 witch also supersedes to a 0523005-201. So with all that being said based on what I have found the wings are interchangeable. According to the log books that I have for the Cessna 172 SN 28849 there or no entries made stating that the wings have been replaced so I feel it is safe to assume that they are original.
And based on the letter Cessna sent me I am ok to replace regardless. The fuel tanks are the same size, the gross weight is the same, The flaps and flap mechanisms are the same. And the electrical I can wire up based on our needs.
I sent this off to y contact at Cessna, Lets see what he says.
Thanks again guys

[Bruce Fenstermacher]

I wouldn't even have asked Cessna or anyone else. Looks like a duck because it is a duck.

[bensmotorworks]

If it has a Cessna PN that is equivalent to the PN you're replacing, it should be a logbook entry but you're at the mercy of your A&P and IA as to what they want to do.

We had a Cessna 150 that had a logbook entry that simply read: "PN XXXXX wings removed, PN XXXX (superseded from XXXX) installed."

Never caused problems with any of the IAs that signed the plane off.

Thanks Aryana, I am the AP/IA I am just nervous, Want to try and glean as much info from the group. And since I posed the question I wanted to post my findings.
Ben

[GAHorn]

Aryana's IA accepted it because he was too lazy to dig out the parts catalog to see if that superceded number was eligible. As your OWN IA... you're too well-informed already.

What are you going to do about the fuel vent system? Pitot tube? Wing tips? Fairings?

[bensmotorworks]

Aryana's IA accepted it because he was too lazy to dig out the parts catalog to see if that superceded number was eligible. As your OWN IA... you're too well-informed already.

What are you going to do about the fuel vent system? Pitot tube? Wing tips? Fairings?

I am going to dig into that tomorrow, But if the wing assemblies are the same part numbers then at this moment I don't see why they wouldn't be the same or have the same mounting holes that I can transfer parts over

[GAHorn]

I don't have the responsibility or authority to approve parts...so I can admit I don't have an answer for that question. But I believe it's correct to say that the IPC is a catalog only.... for the purpose of ordering parts from Cessna or other suppliers. Whether it can be used to identify whether or not a particular item is interchangeable with others... is a horse of a different color (as the Wizard would say.)

[lowNslow]

If the parts catalog isn't an approved source of which parts are legit, what other source is there to use for mechanics to verify part numbers ?

[c170b53]

The aircraft's manufacturer.
IPC's. To this day, the IPC is not considered to be part of the data set provided by the manufacturer to the regulatory system for use in approving an aircraft's in the certification process.
As well IPC's could never keep up with the changes that are made in the parts that make up a modern aircraft. Mistakes happen all the time, sometimes with interesting results. A part has been replaced by another but the IPC doesn't mentioned it's also installed on the other wing and when you replace one, you replace them in pairs. Part is changed, aircraft takes off for test flight and promptly wants to do some acrobatics. Has happened more than you'd like to know.

[GAHorn]

If the parts catalog isn't an approved source of which parts are legit, what other source is there to use for mechanics to verify part numbers ?

You've inadvertently answered your own question. Do you see the words "FAA Approved" ...anywhere in or on your 170 IPC?

(It is not an approved document. It's a catalog... for ordering parts from approved sources.)

Also, (risk of repetition in this regard is a good thing).... the IPC is Unreliable as a reference for assembly. There are numerous errors in the illustrations as far as assembling the parts go. (Fuel selector is one example. It will never shut off the fuel if assembled per the IPC, and it will likely also result in reduced fuel-flow. The elevator cable routing is another... If routed in accordance with the IPC, not only will they not likely be capable of being properly tensioned, .... that method will result in OPPOSITE ELEVATOR... OR REVERSED FLIGHT CONTROLS.

Use the IPC only for ordering parts. (And even then, you might end up owning a part for 17 years not knowing what it does or where it goes...and find out none of the 170's have it after-all.)

[lowNslow]

George, that wasn't my question. My question is with the lack of any other reference, what do you use to verify part applicability?

[bagarre]

George, that wasn't my question. My question is with the lack of any other reference, what do you use to verify part applicability?

Also, what is the approved source for assembling a Cessna 170 or a sub system?
The IPC isn't approved and has quite a few omissions and errors but what else is out there that is FAA Approved data for the 170?

[c170b53]

None, other than the type document, just common aircraft sense, standard practices and lots of acceptable data. It's a case where the " system " developed after the airplane. Common practices, a sense of purpose and good judgement ruled the day when these airplane's first took-off. Then things slowly developed, more of you can't do that, do it this way. Then the system strove to improve itself with more regulations and that's how we have arrived at; you can't do anything unless someone with possibly little sense or idea as to how something works, now is calling the shots.
It's kind of like the path from Abe Lincoln to ah...somebody really bad and possibly fake. and yes the issue is the same up here.
Hopefully the pendulum will swing back the other way.