C170 Airspeed indicator

Thomas Arsenault · Post by **Thomas Arsenault** » Thu Sep 26, 2002 3:12 pm

I have a old airspeed indicator for the 170. It is marked in the correct mph for a 170 but is actually registering in knots. I have had it checked and it is correct over the entire range.

Problem
My CFI says I should correct it before my Commerical check ride but I am used to flying with it. I.E. Downwind 80, Base 70, Final 60. The unit is probably too old to fix.

Question
Where can I find a new/used airspeed indicator for the 170 that has both Mph and Knots on the face? What brand should I look for to fit and replace the existing one?

Tom Arsenault
taa@winternet.com

Post by **GAHorn** » Thu Sep 26, 2002 5:24 pm

Any good instrument shop should be willing to exchange it for you. I have had good experiences with Century in Wichita. 800/733-0116 Be sure to have the pn of the unit you're going to trade in handy when you call. (They'll want to know in order to quote exchange price. Tyhpical price should be about $110-120. For $20-30 more you can keep yours and just get a new/overhauled unit outright.)

zero.one.victor · Post by **zero.one.victor** » Fri Sep 27, 2002 4:07 am

I've had good luck with Rudy Aircraft Instruments in Rudy Arkansas 479-474-8759. Prompt service & reasonable prices. Their current ad in the General Aviation News sez overhaul of a standard airspeed indicator is $65.
If it was me,I'd get the ASI overhauled & just get used to flying in good old American miles per hour,instead of them new-fangled nots!
In it's checkered past,somebody replaced the airspeed indicator in my ragwing instead of overhauling the original. I sure wish they hadn't! The "cool" factor of my panel is at least 25% lower without the original ASI.
If ya do replace the ASI,I might be interested in your original one.

Eric

sj · Post by sj » Sat Sep 28, 2002 1:00 am

All of the students I have sent on Commercial check rides have been required to do so in a complex airplane, the 170 does not qualify for that.

sj

doug8082a · Post by **doug8082a** » Sat Sep 28, 2002 2:31 am

I installed a dual scale ASI in my 170B a couple years ago. I picked it up from Aircraft Spruce from around $250 which included range marks for the 170. I have to agree with Eric, though. It did take away from the "cool" factor on the panel. Personally, I've never had a real need to reference it for the knots portion, but since you are going for your Commercial, I suppose you would require more modern instrumentation. I'm thinking I may overhaul my original ASI and re-install it. If I need knots, I'll just calculate it in my head. If I can't handle that, I shouldn't be flyin'

Doug.

zero.one.victor · Post by **zero.one.victor** » Sat Sep 28, 2002 4:35 am

Doug,someone with a leaning toward smartass-ism might say that would make you a knot-head!

Thomas Arsenault · Post by **Thomas Arsenault** » Sat Sep 28, 2002 1:27 pm

Thanks for all the info. I am taking part of my commerical in an Arrow and most of it in the 170. I have thought about the "cool factor" a lot and was hoping to keep my plane close to origional but I have a 0300A in and not a 145, a new DG and attitude indicator also so the panel is not real origional. I have some concern if I just have MPH on the face I will use what I have become accustomed to over the past 7 years and would try to fly final at 60 mph. This might be good for short field but not for normal landings.

taa

doug8082a · Post by **doug8082a** » Sat Sep 28, 2002 5:12 pm

Hah! Knot-head it is, I suppose.

As long as I can fly the 170, you can call me whatever you like!

Post by **GAHorn** » Sun Sep 29, 2002 3:43 am

Thomas Arsenault wrote:Thanks for all the info. I am taking part of my commerical in an Arrow and most of it in the 170. I have thought about the "cool factor" a lot and was hoping to keep my plane close to origional but I have a 0300A in and not a 145, a new DG and attitude indicator also so the panel is not real origional. I have some concern if I just have MPH on the face I will use what I have become accustomed to over the past 7 years and would try to fly final at 60 mph. This might be good for short field but not for normal landings.

taa

Tom, I'd encourage you to at least have your instrument repaired so that it reads correctly according to whatever scale is displayed. It's unsafe unless the guage is correct whether it's labeled in kts or mph, it should display the correct information.

zero.one.victor · Post by **zero.one.victor** » Sun Sep 29, 2002 3:50 pm

Tom,I gotta agree with George on having the ASI read accurately. As fas as your habit of flying final at 60: when I first got my 170 I put a little white hashmark on the face of the ASI at 65 as I use that as my reference approach speed--a little slower for 3-point short field work and a little faster for gusty-condition wheel landings. I used appliance touch-up paint,you can also use "white-out". Don't need much,just a little mark that draws your eyes. Kinda like painting the front sight on a pistol. Works great--of course,it doesn't guarantee a good landing!

Eric

sj · Post by sj » Mon Sep 30, 2002 1:08 am

Although I am the "new guy" to the 170 assoc, I gotta suspect that the pitot tube on my 170 is just about as bad as the one on my super cub (it is newer!), which is only accurate at certain angles of attack. I don't disagree that it is important to have a working airspeed indicator, but it is MUCH more important to know the attitudes of your airplane and fly those - especially in anything that is not jet powered, but also small ships like the 170, etc. When the proverbial poop hits the rotary cooling device, you don't want to be looking at the panel for answers, you need to be looking out the window. Everybody should know the best glide attitude of thier airplane and be able to trim to it quickly - as an aside, the 172 can be trimmed full nose up and be within a knot or two of best glide. I have not tried this yet in the 170. Of course, untrim it before you power up, or it makes a great lesson for the student on elevator trim stalls...

As for using two planes for the commercial or CFI, most DE's and the FAA no longer tolerate this in our area. The arrow is a great ship for the Com and CFI ratings since all the manuvers are so simple in it. The lazy eights practically fly themselves, and the low wing makes the eights-on a breeze. I require that all my students do it in one airplane and as a bonus it also makes for a shorter checkride. The DE or FAA examiner should actually require you to do orals on both airplanes systems as this is an important aspect of the commercial rating - knowing the bird you are flying in.

sj