The International Cessna^® 170 Association

After re-reading the various threads on the axles and axle bolts, I would like to verify a couple of points.

First, my 170A is pre-19219, so I assume I have 4 x 5/16 axle bolt holes. If I were to replace the axles with any solid aluminum (0541124-1) or hollow steel (1441003-1) axle, would I need to enlarge the bottom holes to 3/8? I assume any axle that I buy today will be drilled with 5/16 top holes and 3/8 on the bottom.

I know this is a good idea anyway, but if it is going to be a difficult and labor intensive project, I may just replace the axle bolts with NAS hardware and avoid carrier landings.

Should I bite the bullet and undertake drilling the gear legs, can this be done with the gear on the plane? What is the preferred setup (drill bits, etc) to ensure that the hole doesn't get elongated in the process. And how does one go about radiusing the edges of the new hole?

I would steer you to Jim Hayton. 360-661-3302 (North Sound Aviation) He has a specialty of recertifying gear legs. I'm sure he can answer your questions.

You can drill them yourself (under the watchful eye of your A&P) and you can radius the hole with a die-grinder.

Yes, it can be easily done with the gear leg on the aircaft. The best method is to use a piloted (not a pilot ) reamer; a 3/8 ream with a 5/16 pilot. A drill bit tends to "chatter" and may track off center through something that thick, especially when trying to start in a pre-existing hole.

I have the reamer you'll need. I will loan it for shipping cost plus a $30 security deposit, if you promise to use a SLOW rpm drill, AND the Boe-Lube I'll send along with it.

A Uni-bit works great for chamfering the hole. I also have a 3/8 countersink that works well.

I think the "pilot reamer" is also called the "Chief Pilot". I've worked for a couple of those in the past.

I'm sending you an email regarding this right now. I do appreciate your help. Thanks!

PilotMike, there's something else I picked up on in your original post of this thread:
You mentioned considering changing your bolts to NAS and keeping your present (original?) axles.

The NAS hardware is certainly stronger than common AN hardware, and if you choose to do that, it's a fine idea, although unnecessary in my opinion.

The problem with axles is NOT the hardware. It's the original, hollow AXLE. All types of aluminum, hollow axles are subject to failure.

The solution is to switch to the solid aluminum ("ski") axle, or to a steel axle (which happens to be hollow but not subject to the same failure mode as the hollow aluminum ones.)

I recommend you drill out/ream/chamfer your lower gear-legs and install either the solid aluminum or hollow steel axles.

I've got a pair of solid aluminum , there yours ,( FREE ) just need your address...I'll consider it a payback to this Forum since I've gleaned so much valuble info and recieved assistance from members like Jim McIntosh..reply my E, JJDV55@Yahoo.com

Hello Mike , I'll send them to you first oppurtunity.Pete Brown got me hooked on the 170 after he took me over the glaciers 2 years ago. As I said above , what a great forum this is , all because of the participants.I feel I've got bragging rights. My nephew bought a'60's Mooney ( why ? ) last June, my first conversation with him was ..."How's your forum ?"...
thanks to all.....John de Visser , Vancouver BC.

Some time ago I saw a mention of titanium axles. Crowd, are they fact or fiction?
-Scott

Tom Anderson used to make beautiful Ti gear legs I would like to get my hands on a set, but have never heard of Ti axle (PMA'd anyway).

Blue4 wrote:Some time ago I saw a mention of titanium axles. Crowd, are they fact or fiction?
-Scott

I thought I linked a Barnstormer's ad for these about a year ago but I searched for it here and on Barnstormers and couldn't find it. I also looked through the FAA's STC's and didn't find it there. As I recall it was somebody in Germany that was selling them for an outrageous amount.

Scott,
In cleaning out my inbox I found the information you were asking about. Titanium axles are available from Erik van Veenen. Eric's e-mail is pent-ax-5dATt-online.de (replace the AT with @). The lead time is 8-10 weeks as they only make small batches at a time. Now, are you sitting down? The price is $1150/axle. I'd want to see a PMA or STC for that price. On the other hand Cessna wants $1067 for their steel axles (p/n 1441003-1), what's another $83 to get titanium?

I haven't paid a lot of attention to axles because I changed to solid aluminum in the 80's. In any case, I didn't have to drill the gear legs, the axles had the right size holes for my plane (1950 170A Ser: 19612). Don't they make them like this anymore?

If you choose to install a steel axle, let me suggest that you DO use NAS hardware. That hardware is specified by Cessna for the steel axle installation on the 180. I have personally seen AN axle attachment bolts stretched to a small remaining neck when used with steel axles for off airport operation. Also consider using the "heavy" AN 363 nut on the single bolt attaching the gear to the airplane. That nut has failed in the past with an axial load and the AN363 is considerably stronger than the AN 365. Jake

4517C wrote:...Also consider using the "heavy" AN 363 nut on the single bolt attaching the gear to the airplane. That nut has failed in the past with an axial load and the AN363 is considerably stronger than the AN 365. Jake

Or install the Pponk "beef-up" kit, if you don't already have it.