Rhetorical Question: Rudder Stop-bolt modification

[GAHorn]

Rhetorical Question: What might you think about this alteration?

I talked to a 170-owner today who had several questions about his on-going Annual Inspection.

One of the questions concerned Rigging….and the Rudder bell crank and stop-bolt came up.

The 170B shares a very similar set of tail-feathers with the L-19/O-1 “Bird-Dog”. The bell-crank of 170’s can be easily damaged where it contacts the AN3 stop-bolt head on the fuselage/tail-cone area…. and the L-19 addressed this issue by adding a “tab” onto the bell-crank to provide additional surface-area to protect the bell-crank. This “tab” is not included in the 170 IPC’s at all…. Likely because the 170 was out-of-production while the L-19 production continued.

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I added this “tab” to my rudder bell-crank as a “minor alteration”.

The Owner who called today has an airplane which was previously altered differently, and by persons unknown. It appears that a larger “head” has been welded onto the existing AN3 Stop Bolt.
His current Inspector has questioned this alteration. I suggested that the airplane should be repaired and returned to original condition….Or that an entry might be made under his Inspector’s authorization, signifying the current condition as a “minor alteration”.

There’s always something “new” to be found on these 80+ year-old airplanes.

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[Bruce Fenstermacher]

I've seem plenty of 170s repaired like the L-19. I don't think the head of that bolt was welded to the original, I think someone found a bolt with an oversized head and installed it.

Not having the actual parts to examine I can't say if I think what has been done with just the oversized bolt head is an adequate repair scheme. I think the L-19 style repair speaks to actually repairing the damaged control horn rather than continue to use the damaged control horn by modifying another part. Whats to stop that control horn from splitting and bending farther back? So without saying the oversized head isn't airworthy I prefer the L-19 style repair scheme and a standard stop bolt.

[cessnut]

It looks like someone used stop bolts from a 150. Coincidentally, 150s have an AD dealing with the horn getting hung up on the bolt.

[GAHorn]

I've seem plenty of 170s repaired like the L-19. I don't think the head of that bolt was welded to the original, I think someone found a bolt with an oversized head and installed it.

Not having the actual parts to examine I can't say if I think what has been done with just the oversized bolt head is an adequate repair scheme. I think the L-19 style repair speaks to actually repairing the damaged control horn rather than continue to use the damaged control horn by modifying another part. Whats to stop that control horn from splitting and bending farther back? So without saying the oversized head isn't airworthy I prefer the L-19 style repair scheme and a standard stop bolt.

It looks like a “thin” nut has been welded or JB-Weld-glued to the original AN3 bolt (if you click on the pic and/or “zoom”)

[cessnut]

Not sure what you are seeing. Those look like 150 rudder stop bolts with a jam nut.

[n2582d]

Edit: Cessnut and I were posting at the same time. He beat me in saying the same thing.

Looks more like the $137 stop bolt, p/n 0433142-1, that Cessnut described.

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AD 2009-10-09 R2 was the result of two fatal accidents where the rudder stop bolts jammed beyond their travel limits when the pilots were practicing spins.

It’s unfortunate that the installer of these bolts didn’t document their work.

[Bruce Fenstermacher]

It looks like a “thin” nut has been welded or JB-Weld-glued to the original AN3 bolt (if you click on the pic and/or “zoom”)

George, I zoomed in. If it's welded on that is one heck of a welder who did it. You have much much more trust in JB weld to think someone might have JB welded the head on. Maybe I need to experiment on my RC Cessna with some JB weld.

Instead I think Del hit it right. And of course Gary beat me to finding the part number and a picture. I've only spent the last hour looking for it. I went down the rabbit hole of finding a 150 parts manual, then perform OCR on the file and still not find a rudder stop bolt of any kind listed. I finally just Googled it which I should have done in the first place. I should know by now to give Gary 2 hrs to find something obscure such as this item. Only then go looking for it. But all is not wasted as in my researching travel I came across the PN the material and description of the pin that holds the catch into the latch of the Cessna latches our 170 and early 172s.

I'll be spending the rest of the day in my laboratory mixing JB weld.

[GAHorn]

EDIT: I FIRST want to Thank Gary… and Bruce… and Cessnut… for their excellent critiques and input.

I’ll have to be more-careful or more-obvious when I “tongue-in-cheek” post (re: the JBWeld)

I’ve spent (wasted) a couple hours looking for the standard C-170/A/B rudder-stop-bolt…and have had Zero luck. The lower rudder-hinge contains the bracket for the stop bolt….HOwever the depiction of the bolt itself and the PN is MIA. It’s like “Searching for Waldo”.

FURTHER EDIT: The IPC for the 170/A/B does not appear to illustrate the "correct" part. ( NOR does the L-19.) I'm suggesting it should be an AN3-10A (or similar grip length) which uses AN960 and/ or AN960L washers beneath the HEAD ...to "set" the length for rudder-travel/stop. An AN365 or AN364 self-locking nut is used inside the bracket (with any addt’l washers necessary) to secure the bolt from turning. The rudder-travel-limits should be re-checked.


I agree that the stop-bolt which Gary illustrated is what appears to be installed in the subject airplane…. but try to find in Any 170 IPC a specification for our airplanes.

Meanwhile…..
… Cessna Distributors display THIS:

“ Manufacturer: Cessna
Part Number: 0433142-1
Weight: 0.02 lbs
Dimensions: 2.55L x 2.15W x .65H inches
ECCN: 9A991.d
Sold Per: Each
Ready To Ship: 3-4 Business Days
$137.11

Availability: 21 IN STOCK”

They have Twenty-One “In Stock”…..but it’ll take One-Hundred Thrity-Seven Bucks Plus Shipping …. AND…3-4 business days Before It Will Ship!

And, it’s not specified for a 170 of any model.

HERE is a depiction of how this bolt is INTENDED to be used on a C-150:

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[cessnut]

Interesting stuff. Please don't confuse me with Del(wingnut), who by all accounts is a very accomplished professional. I'm just a guy that has spent too much time around Cessnas.

[WJRem]

I would like to recognize what an amazing group of Cessna aviators we have. I called George yesterday with the question regarding my plane, N118F, and the "creative" stop-bolt on my aft fuselage. I had other questions for George. To see the detail and follow-up you have all done to help answer my question speaks volumes to the wonderful people in our Association and Aviation in general. I will also give a shout out to Bruce also who has generously taken a number of call from me over the last 5 years and helped me resolve a number of issues in my beloved aircraft.

Thank you to all of you!!!

[n2582d]

For what it's worth, the C-120/140 IPC calls for two AN3H6A bolts (which has holes drilled in the head). The C-140A IPC calls for two AN3-6A (no holes in the bolt heads). These aircraft don't have the bolt mount in a steel bracket like the C-170 does.

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I think the standard bolt used in aviation for a stop bolt is a NAS428 bolt. It is shown in this thread. It's what the C-172 uses through at least 1984.

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