Gear Box Repair Notes from My Experience others may differ

[Metal Master]

Gear box differences between Cessna 170’s, 180’s and 172’s
Essentially the two main landing gear bulkheads and forward door post bulkheads in the case of 172s are the same part number 0513006-9 Fwd and 0513006-103 Aft in all three models of aircraft up through 172 serial numbers 17251822 and P 17257188. And all Cessna 180-185s through 1976 as gleaned from the parts manuals I have on hand. After that the part number changes to 0513374-1 and -5 respectively but it is primarily detail differences in the later part numbers. And could probably be used in rebuilding the gear box for any 170 or early model 180 or 185. The primary differences in the final bulkhead assemblies of a 172 compared to a 170 or 180 is that the 172 forward bulkhead does not have the two steel doublers on the outboard ends (part number 0713495-11) front left and -12 front .right. The 170 and 170 A steel fittings are a different part number in the catalog part number 051495-19 & 20 left and right however they are physically the same when examined in the hand. The -19 is currently not listed as of this date on cessnaparts.com. However the 05114-20 is superseded to 0713495-16. The forward bulkhead also does not have the forward facing extruded angle which goes completely across the forward bulkhead part number 0513006-23. All of these part number 0713495 -*** are currently shown out of stock at Cessna with pricings al from roughly $700 dollars on up to $1700. The other intresting thing about the 172 bulkheads is that in most of the airplanes I have looked in the forward bulkheads are even Piloted for locating the gear box doublers.

The parts picture file I added here was actually from and earlier post but shows the general arrangement. Another interesting thing about the same view in the Cessna 172 Parts catalogs of the "door post" pages is that they use the same drawing of the primary structure which shows the steel doublers on the forward bulkhead in the background. Of course the exploded view detail drawing omits them as they are not used.

Of course the 172’s door post bulkheads do not have the Gear box fittings themselves but the main bulkhead parts are the same part number. Also the top cover (floor panel) for the complete gear box assembly 0513006-11 is a thicker plate on the 170 and 180’s than used in the 172. It is also longer fore to aft because it picks up the line of rivets in the forward facing angle of the front bulkhead as installed in the 170-s and 180’s 0513006-11. The lower skin that closes the whole gear box that goes from gear leg to gear leg on the Cessna 170 and 180 series airplanes is thicker than on the Cessna 172 door post bulkhead area.

In conclusion I have never used any of the Cessna 172 door post bulkheads to rebuild a Tail dragging 170 or 180. However I did convert a Cessna 172 to a tail dragger and found the components compatible and estimate that the individual parts from a 172 could be used to support rebuilding a 170 or 180 along with finding any of the steel plates that might need to be replaced if damaged. Rivet sizes and spacing may be an issue and would have to addressed. I would recommend a close examination of any components being selected as a donor parts from a Cessna 172 and not purchase them sight unseen.
In the views following the picture with the primed parts is what it looked like before I assembled it back into the fuselage and riveted it back together.It is funny to me that I had actually bought the top gearbox skin from Cessna and I manufactured a new one from 2024 T3 .050 aluminum and riveted it on forgetting that I had purchased the new part which I still have out in the garage.I manufactured the bottom skin of the gear box from 2024 T3 .050 aluminum and ended up making two before I was satisfied. I sent that skin to someone here on the forum years ago to help them performing a Flavel Tail wheel mod to a 172. I had a hard time coming up with two of the steel plates that go onto the outboard end and ended up buying from Cessna the left rear bulkhead plate which turned out to be longer than the original 170A part listed extending further inboard buy about 2 inches as I recall. In any case I just cut off and primered the excess length although it would have fir in without modifcationRS.jpg[/attachment]
An additional Note is that with the beginning of the Cessna 172P the forward door post bulkhead was completely omitted from the construction of 172's Making it nearly impossible to convert them to a Tail Dragger swept tail issues not withstanding.

[Metal Master]

Additional Pictures for referance:

This is a picture of a 180 gear box from someone else's airplane It is the same as my 170A gear box

This is a picture close up of the 170A to Door post fit up

Complete 170A to Gear box fir 140 Carry through structure used for Modeling

New Lower Gear box skin manufactured using old skin as Fit

[Metal Master]

One more Picture before I go work on My TCM IO-360 installation:

In the preceding pictures you will see that the Main cabin Bulkheads were severely damaged. I could not purchase them at any price salvage or otherwise. So I ended up repairing them. The one with the Large center doubler I had to manfacture a form block and hammer it out of 2024 T3 .050 aluminum. And then manufacture splice doubelers to splice in the newly manufactured center piece.

[johneeb]

Jim, we are so lucky to have members like yourself willing to share their expertise with us. Thank you!

[ghostflyer]

Well done Metal Master on the clarification on the gearbox, but now I would like to know is the 206 gearbox similar ?

[Metal Master]

Well done Metal Master on the clarification on the gearbox, but now I would like to know is the 206 gearbox similar ?

Not as far as I know. But that would really be stretchering to find suitable parts. The Cessna 210 is a development of the 205 and 206 and the gear box there is considerably wider. My guess is that it is not but I certainly do not know. I have a TU206G that I am responsible for. I will take some rough measurements and take look next week.
Update: Looking at the parts catalog for the Cessna 206 the placement of gear fittings is so much further inboard and of different design of the gear fitting I can see no way a Cessna 206 gear bulkhead or gear box could be used to repair a 170 or 180 of any vintage.

[n2582d]

That is some fine metal work!

Years ago St. Just, a Canadian company, offered a C-180/185 clone kitplane. The Super Cyclone is now offered by Aviatech. I wonder how close their bulkheads are to the original Cessna ones. I see they offer the landing gear box preassembled. Could you call a bulkhead "owner-produced" if you had them stamp one out for you?

[c170b53]

Just awesome Jim, thanks so much

[bagarre]

That is some fine metal work!

Years ago St. Just, a Canadian company, offered a C-180/185 clone kitplane. The Super Cyclone is now offered by Aviatech. I wonder how close their bulkheads are to the original Cessna ones. I see they offer the landing gear box preassembled. Could you call a bulkhead "owner-produced" if you had them stamp one out for you?

You'd have to be involved with the manufacturing process in some way. Provide them the material, verify the quality...
You'd also have to verify it was an identical part and have an A&P willing to install the part.

[n2582d]

I've been replacing gearbox parts due to elongated rivet holes, extra access holes, etc. and adding the PPonk beef up kit. While working there I was looking at the lower rivet holes on the outboard gearbox fittings. On mine it looks like less than 2D edge distance. I'm hoping this is the way it comes from the factory. My second issue is with the angles which attach the outboard castings to the bottom skin, p/n 0713495-5 (fig. 21-50) on the left and the same p/n on the right but which, according to the revision sheet, has been revised to 0742115-25 (fig.21-56). On mine the rivet patterns are different between the two. Do one of these angles need to be replaced? If so, which one is incorrect? PPonk's replacement for the outboard bracket shows a double row of rivet holes.

Click to Enlarge

Click to Enlarge

[n2582d]

Steve at PPonk was able to answer my question. The 180 and 185 require the use of the double row of rivets. The 170 attach angle only requires a single row as I have on the left side. This was my first time talking with Steve and Norma. Great folks, extremely helpful.