Sticking altimeter

My altimeter in my AC-5M is sticking. It works fine when the engine is on or when you tap on the window, but otherwise when gliding it gets stuck up to 100' worth. I suspect that a rebuild will cost as much as a new one will, so I'd rather go the route of fixing it myself (or replacing it with something with added functionality).

Any suggestions on fixing it?

You're just flying too smoothly. Jet aircraft have electric altimeter vibrators to solve this problem.

Mike

On Thursday, November 5, 2020 at 3:46:58 PM UTC-5, Kenn Sebesta wrote:
My altimeter in my AC-5M is sticking.

The vibration from the engine may have trashed the ALT bearings,
a common problem for ASI and ALT in gas-powered motorgliders.
You did not say what kind of altimeter you have?

On Thu, 05 Nov 2020 12:46:55 -0800, Kenn Sebesta wrote:

My altimeter in my AC-5M is sticking. It works fine when the engine is
on or when you tap on the window, but otherwise when gliding it gets
stuck up to 100' worth. I suspect that a rebuild will cost as much as a
new one will, so I'd rather go the route of fixing it myself (or
replacing it with something with added functionality).

Any suggestions on fixing it?

If you're flying in a dusty place and don't have any filters fitted, i.e.
the port in the back of the altimeter is open to cockpit air, could it
have got dust or smoke in it?

If you have an instrument maintainer handy, ask them about the necessity
and cost of servicing.

I'm in the UK, so not much dust in the air here. My altimeter hasn't
misbehaved in the 15 years I've had the glider. For that matter I suspect
it was installed when the glider was new, 51 years and several owners ago.


--
--
Martin | martin at
Gregorie | gregorie dot org

Kenn Sebesta wrote on 11/5/2020 12:46 PM:
My altimeter in my AC-5M is sticking. It works fine when the engine is on or when you tap on the window, but otherwise when gliding it gets stuck up to 100' worth. I suspect that a rebuild will cost as much as a new one will, so I'd rather go the route of fixing it myself (or replacing it with something with added functionality).

Any suggestions on fixing it?

That sounds like normal operation for a mechanical altimeter; certainly for the ones I've
owned. Use an electronic altimeter to avoid the sticking. A lot of varios and flight computers
have the altitude function in them. My next glider will have one of these in it - no sticking,
lots of extra functionality, and replaces 3 instruments!

https://wingsandwheels.com/lxnav-airdata-indicator.html

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Thursday, November 5, 2020 at 2:07:40 PM UTC-8, Eric Greenwell wrote:
Kenn Sebesta wrote on 11/5/2020 12:46 PM:
My altimeter in my AC-5M is sticking. It works fine when the engine is on or when you tap on the window, but otherwise when gliding it gets stuck up to 100' worth. I suspect that a rebuild will cost as much as a new one will, so I'd rather go the route of fixing it myself (or replacing it with something with added functionality).

Any suggestions on fixing it?

That sounds like normal operation for a mechanical altimeter; certainly for the ones I've
owned. Use an electronic altimeter to avoid the sticking. A lot of varios and flight computers
have the altitude function in them. My next glider will have one of these in it - no sticking,
lots of extra functionality, and replaces 3 instruments!

https://wingsandwheels.com/lxnav-airdata-indicator.html

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

ACD Air Avionics Altimeter and more.

http://www.craggyaero.com/acd_altimeter.htm

IN Stock.

Richard
www.craggyaero.com

"ACD Air Avionics Altimeter and more."

There is also the LXNav Air Data Indicator - combined altimeter and ASI.

With either of these devices, is there any battery backup? Is there a legal requirement for a battery independent system? Do you have to have any instrumentation separate from the flight computer since flight computers can display all of altitude/height, airspeed and vario, and can control radio and transponder?

waremark wrote on 11/6/2020 4:58 AM:
"ACD Air Avionics Altimeter and more."

There is also the LXNav Air Data Indicator - combined altimeter and ASI.

With either of these devices, is there any battery backup? Is there a legal requirement for a battery independent system? Do you have to have any instrumentation separate from the flight computer since flight computers can display all of altitude/height, airspeed and vario, and can control radio and transponder?

I contacted Paul Remde of Cumulus Soaring, who also carries the LXNav ADI:

https://www.cumulus-soaring.com/store/lxnav-adi

He says he doesn't have one in stock right now to test, but the manual does not mention an
internal backup battery, so he doubts that it does. His recommendation, and what a lot of us do
already, is two redundant batteries you can switch between. Since the ADI will be my primary
ASI, I may power through two diodes, one to each battery, so no switching is required, and it
will always be powered by the battery with the most voltage.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Friday, 6 November 2020 at 14:58:48 UTC+2, waremark wrote:
"ACD Air Avionics Altimeter and more."
There is also the LXNav Air Data Indicator - combined altimeter and ASI.

With either of these devices, is there any battery backup? Is there a legal requirement for a battery independent system? Do you have to have any instrumentation separate from the flight computer since flight computers can display all of altitude/height, airspeed and vario, and can control radio and transponder?

LXNav states clearly that it is not certified. What a waste of panel space then.

On Thursday, November 5, 2020 at 4:28:54 PM UTC-5, Mike Reid wrote:
You're just flying too smoothly.

About my flying, said to no one ever.

On Thursday, November 5, 2020 at 4:44:13 PM UTC-5, wrote:
You did not say what kind of altimeter you have?

It's a Falcon ALT20INF-3, http://www.falcongauge.com/xinjia/ALT20INF-3.jpg

Replace it with a...!

I love the idea of some of these products, but I'd rather redo the entire panel all at once so that I can optimize for space, ergonomics, and redundancy. If I can make this altimeter work just a little more smoothly it would buy me some valuable time.