Instrument Panel Tilt

[bpaige]

What is the panel tilt angle of the instrument panel in a '52 170B? Info needed to order new AI. Thanks.

[GAHorn]

Instruments (typically horizons) are made for either ZERO or 7-degree tilt panels. This is important in order for the horizon line and the indicator to have full-and-correct capability or range-of-pitch.
Our 170's have "zero" tilt. (If the aircraft is levelled...the panel is vertical.)

[bpaige]

Thank you.

[wingnut]

Instruments (typically horizons) are made for either ZERO or 7-degree tilt panels. This is important in order for the horizon line and the indicator to have full-and-correct capability or range-of-pitch.
Our 170's have "zero" tilt. (If the aircraft is levelled...the panel is vertical.)

I learn something new everyday. Will you elaborate more George? I've never given this any thought, because I never heard about it before. I guess it's more of an avionics deal. What aircraft have a 7 degree tilt? And which way are they tilted? Thanks

[GAHorn]

Many of the multi-engine aircraft have a 7-degree panel. The panel top tilts away from the pilot for better viewing.

[wingnut]

So is the external housing of the unit made different to allow for the panel, or is it the guts of the unit that are different?

[cessna170bdriver]

...Our 170's have "zero" tilt. (If the aircraft is levelled...the panel is vertical.)

Where's that documented George? I had always assumed the same thing until I had a problem with a new attitude indicator once, and (as I remember ) my panel was about 5 degrees from being perpendicular to the upper door sill.

[3958v]

Miles I believe your right. Mine is pretty close to vertical when the plane is sitting on the ground. I seem to remember buying the attitude indicator for zero tilt and have had no issues to date. Bill K

[GAHorn]

...Our 170's have "zero" tilt. (If the aircraft is levelled...the panel is vertical.)

Where's that documented George? I had always assumed the same thing until I had a problem with a new attitude indicator once, and (as I remember ) my panel was about 5 degrees from being perpendicular to the upper door sill.

Good one, Miles!

I seem to have suffered another bran-pharrt....(too much fiber, I guess.)
The part numbers Cessna used for VG (Vertical Gyro/Artificial Horizon) in our airplanes are for vertical panels....and I guess I gradually made an assumption with regard to the panels themselves.... You are correct that they are tilted approximately 5-7 degrees. I called their tech-number and got a fuzzy reply that presumeably Cessna averaged the matter due to the 3-point stance of the 170 and installed instruments for zero-tilt, while the virtually-identical 172 (except for it's level, tricycle-gear stance) used 7-degree instruments. The difference in the instruments is denoted by the "dash no." I see the 170 used -2 T/B while the 172 used -5's. "Don" at tech-support said those numbers indicate vertical and tilted gyros, respectively. (It is rare that anyone at Wichita actually sounds old enough to be credible, however.)

Most aircraft instrument mfr's can accomodate panels from 0 thru 8 degrees, and many will calibrate their gyros for customers, although most are produced for the most common tilts:... zero, five, seven, or eight degrees. Turn and Banks are mfr'd to specific tilt-angles but it's generally relatively unimportant by most folks because, while the rate-of-turn indicated is dependant upon the yaw about the axis...most T&B/Coordinators already have their gyros tilted 30-degrees in order to detect the yaw. The inaccuracies inherent in another error of 0-8 degrees isn't a lot of concern. Horizons are usually considered more important, presumeably because of limited remaining parallax adjustment.

As I ordered my new Sigma-Tek horizon for the latest project this subject came up and the Sigma-Tek representative looked up his data and said that the 170 should have a zero-tilt instrument. I guess I absent-mindedly relegated my brain-cells to assign the same to the panel. Thanks for catching it.

[cessna170bdriver]

...Good one, Miles!... Thanks for catching it.

Thank YOU for doing the legwork to verify that I wasn't imagining things.

[ptporebski]

The esteemed GAHorn wrote,

"Cessna averaged the matter due to the 3-point stance of the 170 and installed instruments for zero-tilt, while the virtually-identical 172 (except for it's level, tricycle-gear stance) used 7-degree instruments."

Can you tell me what the tilt angle is for a 1959 C-172? Am I correct in the George confirmed the tilt angle should be 7 degrees?

I had my AI reworked by SigmaTek (it's a 5000B model) and noted that the horizon line doesn't seem to line up. I thought it was my imagination until I read this email post. Can I check my panel with a level while the plane is sitting in the hanger?

Pete P.

[GAHorn]

The esteemed GAHorn wrote,

"Cessna averaged the matter due to the 3-point stance of the 170 and installed instruments for zero-tilt, while the virtually-identical 172 (except for it's level, tricycle-gear stance) used 7-degree instruments."

Can you tell me what the tilt angle is for a 1959 C-172? Am I correct in the George confirmed the tilt angle should be 7 degrees?

I had my AI reworked by SigmaTek (it's a 5000B model) and noted that the horizon line doesn't seem to line up. I thought it was my imagination until I read this email post. Can I check my panel with a level while the plane is sitting in the hanger?

Pete P.

The only living soul who correctly regards me with esteem is my dog....but is a she, a Labrador and after 14 years now seems to be disregarding me more and more. Perhaps she is finally as smart as I've been telling folks.
If your AI is incapable of correcting the parallax to your levelled airplane, your sitting viewpoint...you can have it calibrated for panel tilt.
You can measure panel tilt with a protractor or digital level.

[busav8or]

I recently had my gyros overhauled by AQI in Wichita and they did a beautiful job. One issue, however, was the panel tilt that is discussed here. When I did the initial test flight after re-installation, I noticed that the AI (old "AN" type) showed about a 4-5 degree pitch down indication in level flight. I got out my protractor and noticed that the attitude taken at the upper door sill on the ground was +11 degrees and the panel showed about a +6 degree tilt for a 5 degree difference. Went flying and measured about a -4 degree panel tilt in level flight at 2000' and 2450 RPM ("high speed" cruise configuration). I'm sending it back tomorrow for adjustment. I'll let you all know the results.

Just thought I would throw out some "real world" tilt numbers if it helps anybody.

[KS170A]

I recently had my gyros overhauled by AQI in Wichita and they did a beautiful job. One issue, however, was the panel tilt that is discussed here. When I did the initial test flight after re-installation, I noticed that the AI (old "AN" type) showed about a 4-5 degree pitch down indication in level flight. I got out my protractor and noticed that the attitude taken at the upper door sill on the ground was +11 degrees and the panel showed about a +6 degree tilt for a 5 degree difference. Went flying and measured about a -4 degree panel tilt in level flight at 2000' and 2450 RPM ("high speed" cruise configuration). I'm sending it back tomorrow for adjustment. I'll let you all know the results.

Just thought I would throw out some "real world" tilt numbers if it helps anybody.

Coincidence? I just flew my 170A today with a freshly-overhauled AI (by AQI) and noticed nearly the exact same thing. I previously had thought the 170 to have a zero-tilt panel, but now am wondering. AQI may have 2 indicators coming to them this week!

The good news is AQI is very good about correcting problems. I had an altimeter that had been overhauled by them in 2010. I had a major project with the airplane and didn't fly it until this spring, at which point I noticed my altimeter thought we were at 74,500 MSL! They fixed the 10,000 pointer at no charge, nearly 2 years after they did the overhaul.

[GAHorn]

Josh...is that a picture of your gyro ...WHILE IT IS SPINNING AT PROPER SPEED? Or is it while it's sitting on the ground in the hangar at REST? (Makes a difference! Also makes a difference if the airplane is airborne or not.)