Recommended Modifications/Repairs for 170 Owners

[Bruce Fenstermacher]

At the same time you replace the main leaf spring, replace the AN7-20A bolt that attaches the tail wheel to the main spring. This one lasted at least 17 years with an average of 50 hours a year and one landing per hour that's 850 hours/landings. If it breaks on landing it WILL ruin your day.

Photo on 2010-07-01 at 15.57.jpg (77.72 KiB) Viewed 85880 times

[GAHorn]

At the same time you replace the main leaf spring, replace the AN7-20A bolt that attaches the tail wheel to the main spring. This one lasted at least 17 years with an average of 50 hours a year and one landing per hour that's 850 hours/landings. If it breaks on landing it WILL ruin your day.

Photo on 2010-07-01 at 15.57.jpg

EXTREMELY fortunate you were taxying slowly and on grass. When this breaks on takeoff or (more likely) on landing...the tailwheel flails the rudder to smithereens....adding considerable to the cost and trouble.

[Romeo Tango]

Heading into the annual, so I revisited this wonderful post to check on the entries and any new updates. All good stuff, thank you for the contributions. I've put in two items over the years that are worth mentioning.

a) Mixture cable/control replacement. The mixture control installed when I bought the airplane (original as far as I know) was a gimpy push/pull deal that always felt like it had the potential to fall apart when used. It was also an adventure to lean the engine properly without 500RPM gyrations. I fly at 10-12K quite often and leaning is pretty important. The McFarlane replacement is solid and has a twist vernier control for fine tuning.

b) control cable replacement with new galvanized modern equivalents (McFarlane again). I had a flap cable fail on a preflight, so I decided to replace all cables at the next annual, including all of the hardware. Cost out the door was <$1500 plus labor. If you are replacing fabric, repainting or otherwise have the airplane torn apart, this is a very good insurance policy against the inflight failure that would make for a lot of paperwork. Plus the act of going through this much rerigging will force your AP to dig deeply into nooks and crannies and find those elusive corrosion spots.

[KG]

Regarding using the L19 eye bolt on the tailwheel (item 14 on the first post of this thread), use the nylon locknut with caution. See this post with information about the nylon locknut:
http://www.cessna170.org/forums/viewtopic.php?f=2&t=7845

short version --- replace the nylon locknut with a steel locknut.

edit: the last L19 eye bolt that I bought did not come with a locknut, nylon or otherwise. So you'll have to supply your own steel locknut. The price of the bolt had also gone up considerably. I doubt if I would buy another one as it was over $40 delivered.

[architect1]

I use the True-Lock axle nut with my straight skis to keep the axle shaft open for my dolly's. They work fine.

[gfeher]

It appears that the L-19 tail wheel eye bolt has come back down in price. I just purchased and received one from Air Repair for $21 plus postage. Not the cheapest bolt you can purchase, but less than the $40 someone mentioned it was going for a few years ago.

[GAHorn]

Regarding using the L19 eye bolt on the tailwheel (item 14 on the first post of this thread), use the nylon locknut with caution. See this post with information about the nylon locknut:
http://www.cessna170.org/forums/viewtopic.php?f=2&t=7845

short version --- replace the nylon locknut with a steel locknut.

edit: the last L19 eye bolt that I bought did not come with a locknut, nylon or otherwise. So you'll have to supply your own steel locknut. The price of the bolt had also gone up considerably. I doubt if I would buy another one as it was over $40 delivered.

BE CERTAIN of the grip-length of the eyebolt versus the thickness of your tailsprings. The L-19 eyebolt was intended for the thicker L-19 mainspring and when used on the 170 mainspring might be a bit too long in the grip, requiring at least one, and maybe two addt'l flat washers in order to guarantee that the lock-nut used does not "bottom-out"...and will retain it's proper torque.

[thanatos767]

Has anyone installed shoulder belts in a 170A?

[hilltop170]

I had the BAS lap belt and shoulder harness conversion installed in my 170A. Nut plates were installed overhead in the rear spar carry-thru which is detailed in other threads in the Forums.

I got the version that has tabs on the shoulder belts that assemble onto the lap belt tab and come completely apart when released and adjusters on both sides of the seat belts.

BAS seat belts/shoulder harnesses with full-release latches and adjusters on both sides of seat belts

Shoulder harness bracket attach points, 4 bolts shown along front rivet line on rear spar carry-thru replacing existing rivets

[ghostflyer]

Richard,
Did you use a STC instruction sheet from the manufacturer of the belts For the installation. I have gone down the same path as you with the belts but I went to Cessna for advice And/ or a authorised drawing .
I had to place and seal a plate on top of my roof of the fuselage , a plate of 36thou of 7075 -T6 . I had to proseal the plate to the top of the skin externally. It was a messy job with proseal dripping through the rivet holes . I had proseal in my armpits , in my beard ,but not in my hair as I haven’t any. I could send you a copy of the modification for your comment but I have placed it in a safe place and I can’t remember where it was. Cessna went on also in that information sheet about corrosion that could be present in the hat section. This area was in very good condition on my aircraft but we made a probe with fine holes in it attached it to a spray gun and painted internally The hat section with zinc chromeate .

[gobrien]

14. Install an L19 tailwheel tie-down eyebolt (PN 0642105) in lieu of the AN7-22A bolt that holds your tailwheel assy to the main leafspring.

Gents,

I have looked in the 170 IPC Fig 20 and 170B IPC Fig 27 and 28 (in case it changed later) and in both cases the tailwheel assembly is attached to the main leaf spring with an AN7-10A. I see references in various articles to the above mentioned AN7-22A. Was there an AD or SB or something that I'm missing that changed the -10A to a -22A?

Thanks,

Gareth

[170C]

Comment & Question I may be repeating myself on this, but I originally purchased an L-19 tailwheel bolt from Air Repair, Inc in Cleveland, MS back in July of 2004 when George brought this item to the association's attention. It worked well for many years, but eventually I noticed the bolt was turning 10-20 degs. I would tighten the nut, but the problem would return. I believe it was George who suggested a torque of 50-60 lbs which I used, but the problem persisted. This past October (2019) I purchased a new bolt (P#0642105) and installed it using Nord-Lock Wedge Locking washers and a steel nut. To date I have not had any further issues with the bolt moving.
My question - With the installation of the tail wheel springs, does anyone put any kind of material (baffeling or otherwise) under the springs in the spring channel?

[gfeher]

Gareth, many (likely most) C-170's now have a Scott tailwheel, and a longer AN7 bolt is needed for that tailwheel. The figures you mention from the IPC show the original tailwheel. Fig 98 of the 170B IPC, for example, shows the "optional" Scott tailwheel version, and you'll notice the bolt listed is an AN7-20A, which is what I have on my plane with a Scott tail wheel. I'm not sure why the post you quoted refers to a little longer -22A bolt, other than to say that in the US, an A&P can exercise some descretion when choosing a bolt length within the limitations/requirements of AC43.13-1b, such as the number of threads that must show and the maximum number of washers you may use. On my plane, the -20 length works. By the way, in the US, the IPC's are not regulatory. Although they are extremely helpful in determining what's on the aircraft, ultimately they are just catalogs for ordering parts. Also, they do contain errors,

[dstates]

I ordered a L-19 tailwheel bolt without fully doing the research. I have a Maule tailwheel and it will not work with a Maule.

[gobrien]

Thanks Gene,

That makes sense. I have become familiar with mistakes in the IPC!

Gareth