climb prop question

How to keep the Cessna 170 flying and airworthy.

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bagarre
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Re: climb prop question

Post by bagarre »

Yep. Just pulled out my copy of SA7441SW. (I have an O-300D) and it does in fact call out the 1A175/SFC propeller.

For Seaplane Only.
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jatkins
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Re: climb prop question

Post by jatkins »

We interrupted it as follows.
On my copy of SA7441SW, on page 1of 2 installation procedures,
item 4 , which refers to propellers, , section A talks about sensenich an McCauley Props, ,
then it states , " and1A175/SFC8040 seaplane not to exceed2360 rpms. "

It was interpreted as the 1A175/SFC 8040 is a seaplane prop.

But it does NOT say seaplane only.
Just as people run seaplane props on C 180s and C 185s on wheels regularly,
and we were able to reference DM 8040 series props on C 170 STCs with no seaplane limitations.

We checked the prop ground clearance, in flight attitude, and found 16 inches,
I have 180 gear legs and 8.00 wheels.
CF-HER
52 170B 20292
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jatkins
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Re: climb prop question

Post by jatkins »

I also purchased the STC from Wick Air in Palmer Alaska. ( SA 632AL )

Which is actually for a DM 80 series prop ( 8 bolt flange )
His STC includes a nice Flight Manual Supplement, the limitations
instructions, and ICAs.

Also if you look up the Type Certificate for these Props, P-857.
On Page 4 near the bottom of the page at note 6 it talks about
differences and "interchangeable Propellers "

If you read through the Type Certificate, the only difference between the 1A175/DM80 props
and the 1A175SFC80 props is the 8 and 6 bolt hubs.
Last edited by jatkins on Sat Jan 31, 2015 5:22 pm, edited 1 time in total.
CF-HER
52 170B 20292
bagarre
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Re: climb prop question

Post by bagarre »

I'd say to take that up with your FSDO and if they and your mechanic are willing to sign it of, go for it.

However, SA7441SW in itself is not approval to install the 80" prop on a 170 land plane. I don't know how else to interpret 'seaplane' other than equipment for a seaplane.
Also Drawing Number RM-2 REV-2 of the STC calls out:
Item No. Part Number Description
1B 1A175/SFC Propeller, McCauley Seaplane only

Which doesn't leave much to interpretation and installation item 4 refers to drawing RM-2.

In your case, the 180 gear legs and 8:00 tires probably contributed to the approval as you have much more clearance with that set up.

Again. Your best bet to take all this to your FSDO and have them and your mechanic agree with this.
bagarre
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Re: climb prop question

Post by bagarre »

jatkins wrote:
Also if you look up the Type Certificate for these Props, P-857.
On Page 4 near the bottom of the page at note 6 it talks about
differences and "interchangeable Propellers "

If you read through the Type Certificate, the only difference between the 1A175/DM80 props
and the 1A175SFC80 props is the 8 and 6 bolt hubs.
Now if the Prop Type Certificate actually states that the 1A175/DM80 and 1A175SFC80 are interchangeable or at least the bolt patter is the only difference, then you have further data to ask for the approval. And that's good data to know.
But there this is all data to take to the FSDO to get approval. It isn't approval in itself.

Most of this is an academic discussion 'cuz you'd need to find someone that wants to make a beef about the prop you're swinging.
Where I live, that's not hard to find. In other places, people may not notice nor care for years and years.
But that's a 'can' vs 'may' discussion.
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Joe Moilanen
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Re: climb prop question

Post by Joe Moilanen »

I have an 8043 1A175 on my '53 170B with an O300D. I have a <one time STC> to cover it. I still have the early gear (spongy), run 800 tires, and haven't had a problem with the combo in the 26 years that I have been flying it. I can submit copies of my one time STC if it helps someone to get a field approval.

Joe
kbbell
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Re: climb prop question

Post by kbbell »

I found the best way around "seaplane only is to leave it on floats all year.
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mit
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Re: climb prop question

Post by mit »

I have been passed by cubs with my 80/40 on floats! It don't make much difference on wheels or skis with that prop on. You have to watch out you don't over-speed!
Tim
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KG
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Re: climb prop question

Post by KG »

Here is my previous discussion about this topic:

http://cessna170.org/forums/viewtopic.php?f=27&t=11030

I determined with a reasonable amount of certainty (in other words I really don't know) is that since the 80 inch prop has been tested and approved for use on this engine, then it could be field approved on a land plane if it meets the ground clearance requirements. I abandoned the idea of the long prop after my mechanic took some measurements and thought that with my early 170 landing gear it did not have adequate ground clearance. Perhaps later gear, 180 gear, or bigger tires would have been ok.
53 170B
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lowNslow
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Re: climb prop question

Post by lowNslow »

Hard to imagine having the prop 2 inches closer to the ground would create clearance issues, even with the older gear.
Karl
'53 170B N3158B SN:25400
ASW-20BL
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KG
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Re: climb prop question

Post by KG »

I thought so too. I wasn't there when they measured it and I'm sure they didn't get real involved like loading it up to gross or flattening a tire or anything like that. I think it was just close enough that they were concerned about it. It may very well have been ok, I don't know for sure because I didn't pursue it further.
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bagarre
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Re: climb prop question

Post by bagarre »

Speak of the devil
http://www.barnstormers.com/classified_ ... +prop.html
MCCAULEY 80/40 1A175SFC PROP • $1,100
bagarre
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Re: climb prop question

Post by bagarre »

An interesting twist in STC SA7441SW

In my copy, Drawing RM-2 Rev-2 dated 2/17/98 calls out the 8040 prop and clearly states it 'Seaplane Only'.
In John's copy, Drawing RM-2 Rev-2 dated 2/17/98 doesn't mention the 8040 prop at all.

However, installation instructions in both STCs state the operating limits of the 8040 prop.

John's copy of the STC there is no 'Seaplane Only' statement so it could be interpreted as allowing the 8040 to be installed.
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GAHorn
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Re: climb prop question

Post by GAHorn »

The seaplane (sitting high up on floats) does not have the ground-clearance issues the landplane is required to meet in accordance with certification rules.

(Our airplanes were certificated IAW CAR-3 which stipulated 7"-9" ground to prop clearance. 7" for trikes and 9" for conventional gear.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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jatkins
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Re: climb prop question

Post by jatkins »

I am certain that the ground clearance is not an issue.

Wicks Inc. in Alaska, has an STC for the DM 80 series prop on the 170 Series LANDPLANE .
I have this STC , it is well documented. It has instruction procedures , ICA, and
an Approved Flight Manual Supplement.

The STC does NOT require large tires or different gear legs.
CF-HER
52 170B 20292
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