Instrument Panel Tilt (degrees)

[dj2790]

This subject is not really new, but I'm rehashing it. I have read in different places different answers as to what the tilt of the C 170B instrument panel is. I am considering buying the new R.C.Allen digital attitude indicator and they want to know the panel tilt in degrees. What is the answer to that question? Does anybody know?

Thank You in advance

[flyboy122]

I don't know about the tilt, but I had some experience with the RC Allen digital gyro and it wasn't very hard to tumble it. That was a few years ago, and they may have gotten better.

DEM

[ghostflyer]

A number of people are not going to like what I say about the digital Allen instruments . We have a number through the shop and found them to be nothing but trouble . Save your money and buy fuel for flying . A glass of water on the glare shield is a more accurate instrument . We have had them locking up , very noisy and toppling over very easy . Ok that's the nice things said , now the rest is ............

[lowNslow]

What are they talking about when the say panel tilt, is it the angle of the panel when sitting on the tailwheel?

[edbooth]

What are they talking about when the say panel tilt, is it the angle of the panel when sitting on the tailwheel?

It's the angle of the panel in straight and level flight.

[LBPilot82]

Yep, 7 degrees. When I put my new zero degree AI in, it came back out after a few weeks since the horizon didn't line up. Put in a new 7 degree tilt unit and it's perfect.

[Kyle]

Older thread but asking for some help. We installed a RC Allen digital electronic attitude indicator (RCA2600) and a Garmin G5 HSI which also has the electronic AI. I'm having erroneous readings while flying and its not good. The only way I can get the instrument to properly indicate level flight (When actually flying level) is to hit the two "Sync" buttons simultaneously, which you are NOT supposed to have to do unless your AC flys wings level with a pronounced nose up or down attitude. The instrument was factory set to 4 degrees tilt, and based upon the above comment that may be wrong. On the ramp, it shows 13 deg. nose up. When your airborne and level off, it shows about 5/6 deg. nose up.

Fly along for a bit in level flight and it does not level out. When decending, at a steady 600' per min decent, it shows wings level. Now maybe, with the 170 throttled back, in a steady decent, the plane IS actually level (Fore/aft), I'm not sure. The installation manual for this RC Allen IA states, when the tilt is set, you do NOT have to do anything to the gage (except insure the 3 min initialization time) and it will act correctly in initial climb, level and descending flight. So my questions to the group...

1) Does anyone have recent experience with this issue, or measuring panel tilt for the 170B (not sure if different from other 170 models) ?
2) in checking panel tilt, nose to tail - seat rails level ?, then vertical with a square, then a measuring device zeroed, and measure tilt angle from the vertical zero ?
3) Anyone using another type of digital electronic AI ?

Any insight is appreciated. Thank you,

Kyle Takakjian

[GAHorn]

<EDIT>. This post has errors of memory in it and should be taken with an extra grain of salt. Thanks to Miles I reviewed Sigmatek data and found they make their horizons with zero and eight-degree tilts, and the 170 does have a tilted panel...not zero.

This was investigated a few years ago and I ended up talking to Cessna Technical support who stated that instruments for the 170 series should be “zero degree” instruments. Cessna tech stated the 170 “water line” is not level when the airplane is in level-flight at many weights and speeds but that “zero tilt” instruments are called for.
Most instrument panels in airplanes are not actually vertical, but are tilted forward for better pilot-viewing. Instruments must take this into consideration and most are specified at zero, 4, 5 or 7-degree tilts, but usually can be custom-calibrated for other tilts. If the 170 is leveled in accordance with the upper door sill (as called for in the rigging instructions) the panel is -5 (according to those who’ve done this exercise) and Cessna called for zero-tilt instruments for the 170 series and -7 for the 172.
This was confirmed for me when I ordered a new Sigma-Tec AH and Sigma-Tec researched their data and confirmed for me that the 170 should use “zero” tilt horizon.

(I’m thinking those few 170s with vacuum pumps and electronic gyros seem to have issues when they “set” instruments during pre-take-off run-ups then find while in level-flight that their instruments need to be re-indexed. Venturi-equipped (original) 170s don’t usually complain about such matters because their instruments are commonly adjusted after level flight is achieved and not changed thereafter.)

[brian.olson]

Kyle - I feel/felt your pain. I had the G5 HSI installed last year in my panel. The HSI - as you know - also allows you to switch over and view the instrument as the artificial horizon (typically in an emergency situation, but you can do it on-demand) and it was never "zeroed-out" by the installer. As you also know the experimental G5 allows for a "zeroing out" in-flight, while the certified version does not, so the process isn't quite as straight-forward.

A few months ago I decided to buy a digital protractor and try my hand at figuring out what "zero" meant. I measured the at-rest angle of both the panel and the upper door frame as well. I let the G5 go through it's leveling process at-rest per the instructions. Lot's of trial and error, and never really got the calculations to work out 100%, but after adjusting the angle a few tenths-of-a-degree at a time before each flight I found what I think is "zero" during straight-and-level flight. While that is specific to the G5 numbers are numbers and I suspect you could also port them over to your AI as well.

I plan on stopping out to the hangar either later today or tomorrow and I'll write down the figures for you and post as a follow-up. At least that will be a very close starting point, and then you can adjust up or down to fine-tune from there.

[cessna170bdriver]

This was investigated a few years ago and I ended up talking to Cessna Technical support who stated that instruments for the 170 series should be “zero degree” instruments. Cessna tech stated the 170 “water line” is not level when the airplane is in level-flight at many weights and speeds but that “zero tilt” instruments are called for.
Most instrument panels in airplanes are not actually vertical, but are tilted forward for better pilot-viewing. Instruments must take this into consideration and most are specified at zero, 4, 5 or 7-degree tilts, but usually can be custom-calibrated for other tilts. If the 170 is leveled in accordance with the upper door sill (as called for in the rigging instructions) the panel is -5 (according to those who’ve done this exercise) and Cessna called for zero-tilt instruments for the 170 series and -7 for the 172.
This was confirmed for me when I ordered a new Sigma-Tec AH and Sigma-Tec researched their data and confirmed for me that the 170 should use “zero” tilt horizon.

(I’m thinking those few 170s with vacuum pumps and electronic gyros seem to have issues when they “set” instruments during pre-take-off run-ups then find while in level-flight that their instruments need to be re-indexed. Venturi-equipped (original) 170s don’t usually complain about such matters because their instruments are commonly adjusted after level flight is achieved and not changed thereafter.)

That hasn’t been my experience. I replaced an RC Allen AI about 10-15 years ago and put in a zero tilt unit. It took the full range of adjustment to center the horizon bar, but the movable face didn’t line up with the fixed part. I replaced it with one set up for a 7-degree forward tilted panel and all was well. Last year I noticed it was getting lazy so I had it overhauled with the same tilt, and it worked perfectly out of the box. I do have a standby manifold vacuum system, and it indicates roughly 10 degrees nose up while taxiing, as you would expect.

[GAHorn]

That hasn’t been my experience. I replaced an RC Allen AI about 10-15 years ago and put in a zero tilt unit. It took the full range of adjustment to center the horizon bar, but the movable face didn’t line up with the fixed part. I replaced it with one set up for a 7-degree forward tilted panel and all was well. Last year I noticed it was getting lazy so I had it overhauled with the same tilt, and it worked perfectly out of the box. I do have a standby manifold vacuum system, and it indicates roughly 10 degrees nose up while taxiing, as you would expect.

Thanks for reminding me, Miles... you said that before, IIRC. I’ve slept since then, but this may be another example of Cessna having lost their depth-of-expertise over the years...(and I now regret having posted my comment above.) The comments of those who had leveled the upper door-sill and measure would indeed seem to lean that way, if you’ll pardon the pun. (I have added an edited comment to that earlier post.)

[Kyle]

Thank you everyone for the respnses. I was at the hanger today and measured the tilt. Interstingly, 7 degrees. What I did find was the floating panel which the instruments fasten to was 3.9 deg., likely due to sagging mounts. I changed them about 15 years ago but maybe it's time again. I will reach out to RC Allen and see what the process is to have them change the tilt from 4 to 7.

I'll keep everyone posted as to what they say. Brian, are the instructions for setting the Garmin G5 in your operators manual or the installation manual?
Thanks again to all.

Kyle Takakjain

[brian.olson]

Kyle - the instructions were in the "installation manual". My avionics shop gave me a copy of the install manual when the G5 was installed so that I had a copy of everything. Unfortunately I didn't get out to the airport as expected but still intend on copying down the figures that I used.

[brian.olson]

Kyle:

Update for you. Stopped by the hangar this morning and snapped some photos.

First off ... here's the angle of the top horizontal door support while in an at-rest position. Note that along the length it varied by about .5 degree, but from my vantage point it averaged around 11 degrees for my plane.

62C Door Horizontal Angle.JPG

Angle of the panel when in an at-rest (3-point) position for my plane. I couldn't get a 100% accurate measurement from the floating panel, so this is as close as I can get. Let's call that 84 degrees from the floor. Note that this is not the panel angel when in straight-and-level.

62C Panel Angle.JPG

You should be able to calculate the actual angle of the panel when in straight-and-level flight by taking the the reported angles of the panel and the horizontal portion of the door while in a 3-point position into account. Let's call that a panel angle of 5-ish degrees or so if we assume the horizontal portion of the door is actually horizontal while in straight-and-level flight.

Specific to the G5:

I ran the auto-collaborate function on the G5 while the plane was at-rest (3-point position) and found the following:

62C G5 Auto Calibrate.JPG

I ran through the calculations in the install manual to try to adjust the offset number which would - theoretically - give a perfectly level reading during straight-and-level, but for whatever reason just couldn't get it to resolve correctly. Eventually, after trial-and-error, I landed on the following, adjusted, settings post-calibration:

62C G5 Final.JPG

Hope this helps ....

Brian

[Kyle]

Brian, thanks so much for the info. After rechecking the angles, sure enough, it is off by 3 degrees. I contacted RC Allen yesterday and they said they can reset the tilt angle if I send it to them. Its a 200.00 flat fee to change it.

Kyle