The International Cessna 170 Association

Working on placards... I've noted that some planes have a 10 degree flap position and some don't. My manual for my 1952 170B doesn't mention a 10 degree setting but my plane has a 10 degree notch. I am wondering if someone added the 10 degree notch at some point. The records do not say anything. Which 170's had the 10 degree flap setting?

Yes, someone added the 10 degree setting to your plane. The '52 and later models up to SN 26504 were not delivered with the 10 degree setting. But all B models are certified for the 10 degree position and many added the 10 degree notch to the flap ratchet using a drawing available from Cessna. A copy of it is available in the MX Library. My '52 model still has the ratchet in the original condition without the 10 degree notch. I guess I don't know what I'm missing because I don't feel a need to change it.

I have the 10 deg flap notch and use it on a hot day for take off. It gives me a little better edge in take off distance and climb. When it’s very windy on a cross wind I have used also , slowing the landing down a couple of knots . It’s like having a $10 note extra in your wallet.

My first 170B had the 10 degree spot. I also used it on takeoff rather than the 20 degree position. It gave a little more positive rate of climb without the drag of the 20 degree position IMO. Would I run to the hanger with a file if I didn't have the 10 degree position? No. But I'd add it when it was convenient and it not cost was involved.

And your basis for approval for serial numbers 20267 and later is right there in the TCDS:

Wing Flaps
All Serials S/N 20267 and up eligible
Takeoff
Retracted
0°
1st Notch
10°
2nd Notch
20°
Landing
3rd Notch
30°
4th Notch
40°
Note: S/N 20267 through 26504 were delivered without the 10° Notch.

Thanks for the information guys!

Bruce and ghostflyer, do you use 10 degrees on grass, or were you talking about asphalt? I fly mostly on grass now, where I always use 20 degrees for taxi and takeoff. But I've gotten so used to the 20 degree setting that when I takeoff on asphalt (without flaps), it seems sluggish. Also, the transition from 20 degrees to flaps up on climbout seems kinda long. There's always that period where the rate of climb decreases until the airspeed catches up.

Gene, for the most part my takeoffs with that plane where from asphalt. I didn't really change my technique on grass as flaps go and really never thought to compare 10 to 20 degrees on grass.

I go with what Bruce says , that’s my thoughts exactly .

OK. Thanks for the input.

KG wrote:And your basis for approval for serial numbers 20267 and later is right there in the TCDS:

Wing Flaps
All Serials S/N 20267 and up eligible
Takeoff
Retracted
0°
1st Notch
10°
2nd Notch
20°
Landing
3rd Notch
30°
4th Notch
40°
Note: S/N 20267 through 26504 were delivered without the 10° Notch.

I don't read it quite that way at all. But approved modification ...it IS. Cessna's (Textron actually) position as mfr'r provides the approval in that their parts-approval process authorizes the early non-10-degree sector until "part supply exhausted, then substitute 10-degree sector" part number.

{Edit] TCDS does state “All” “eligible”. Thx KG