Attitude Indicator not working

SPAJC

SPAJC

Pre-takeoff checklist
Joined
May 15, 2014
Messages
395
Location
Spartanburg, South Carolina
Display Name
Display name:
Jeff
Greetings all!! I have a qustion about my Attitude Indicator. Some background:

I purchased this airplane a few months ago. It had been sitting in a field for quite some time. It is a 1965 Cessna 150F. A little work and time and its airworthy and legal again.

So, the first couple of times that I fly it, the Attitude Indicator, although sluggish at first, worked. When I say sluggish, I mean the horizon bar didnt come down into view until I was on the roll. After that it worked fine. It did that twice. Ever since, you can only see the horizon bar when the engine is not running. Once you start the engine, the horizon bar very quickly goes up to the far left corner of the face and cannot be seen. This is where it stays until you shut down.

This is an "old style" indicator. It has a black face with a white horizon bar, and basically three straight-ish lines in the middle to represent the airplane. It has a center located adjustment knob. I don't know what the make and model are right off the top of my head, but will find out and repost.

I'm just wondering if there is something that I don't know about this indicator that I should know and be doing or if it is truly unserviceable as I suspect.

The vacuum gage reads good and all other imstruments are working properly.

The main reason I question this is that it worked previously and then did not...no symptoms or warnings otherwise, other than being a little sluggish at the start. Thanks for any input!


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The AI being a gyro instrument is subject to wear, internal dirt and just getting old. Sluggish is a symptom of the gyro taking some time to spin up and to react. May be time for a rebuild.
 
Concur with Marauder. With no other signs of a leak somewhere in the vacuum system, and the plane having been allowed to sit, the most likely culprit is the bearings inside the AI, and that means overhaul/rebuild/replacement.
 
I replaced the one in my 150 and was later sorry. Can't honestly think of a reason to need one if I'm doing things correctly.
 
Not long after I bought my plane both gyros went (independently) TU on me. It turned out neither had an intake filter and the thing was sucking all the crumbling firewall insulation into it. To top it off, my DG when removed had a piece of masking tape on the top of it proclaiming it's cost to be "$5".
 
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If you were to start the engine, the horizon bar would rise to the upper left out of view...just for illustration. Thanks for all of the replies!!!!


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I think you might just need to outright replace that relic.
 
I'd just put an "inoperative" sticker on it and keep going. Those things don't come cheap.
 
I'm personally not a big fan of letting things break on airplanes and leaving them that way. Esp. a six pack item. You'll really kick yourself in the ass if you ever need it. Don't let a nice airplane become less nice. Plenty of VFR only aircraft are built for attitude indicators. There is a reason for that.

Hell even my Flybaby has a vacuum turn and bank (venturi driven) and yes I make sure it works and if it broke I would replace it.

Talk to Aircraft Quality Instruments and it'll be fixed for $400-ish and last a very long time.

http://flyaqi.com/gyro.htm
 
jesse said:
I'm personally not a big fan of letting things break on airplanes and leaving them that way. Esp. a six pack item. You'll really kick yourself in the ass if you ever need it. Don't let a nice airplane become less nice. Plenty of VFR only aircraft are built for attitude indicators. There is a reason for that.

Hell even my Flybaby has a vacuum turn and bank (venturi driven) and yes I make sure it works and if it broke I would replace it.

Talk to Aircraft Quality Instruments and it'll be fixed for $400-ish and last a very long time.

http://flyaqi.com/gyro.htm
Click to expand...
^This. Despite your intentions of always flying VFR, there is always that one chance that you could end up in marginal conditions or worse. In that case, you're going to want that AI to work. A few hundred bucks is more than worth it for peace of mind, IMHO.
 
I fully intend to have it fixed or replaced. I likewise dont like leaving things broken....especially on such a large investment. However, I do agree with and understand both methods of thought...to each their own. All of the input is always appreciated regardless! Thanks!!!


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jesse said:
I'm personally not a big fan of letting things break on airplanes and leaving them that way.
Click to expand...

Agree. Even a less important item, I would either fix or remove it. Having an airplane with a bunch of deferred maintenance items leads to more...like the broken window theory of crime.
 
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