[mlawton]

I own a Cessna 172 and I have replaced 3 Artificial Horizons in 15 years!
They are bog standard R C Allen 22-7, New vac filters are fitted at every annual. Fitted by a licensed engineer. Anyone have similar experiences or know why such a short life. Aircraft parked outside with a Cambrai cover and does about 175 hrs a year. My licenced engineer recommends new units, says a recon will only do half the time! £950 a go plus fitting! Any ideas?? Thanks

[T67M]

Sounds familiar - we generally repair or replace one gyro (AI, HSI or T&B) instrument every 12-18 months - but we do aerobat the units so life is probably shorter as a result. We're now considering electronic replacements such as the Garmin G5.

[Gas Guzzler]

Same here, 2 x Artificial horizons and 3 x Direction Indicators in 11 years. The last DI has lasted 3 months so is defo going back!

[G-BLEW]

Buy a Garmin G5 instead.

Ian

[kui2324]

Seconded on the buy a Garmin G5!

[mlawton]

Certified G5 s over £2k plus fitting!

[mikehallam]

AVCom EFIS AH around £850 inc. VAT and DIY for free, uses standard ~3" panel aperture - I removed old VSI to make space.

mike hallam.

[G-BLEW]

Not sure that's OK for certified aircraft is it? Haven't been able to track it down.

Ian

[Lefty]

I believe I've had the same AH in my a/c for 32 years (can't ever remember replacing it). But I've had two vacuum pumps in the same period.
The A/C is parked outdoors on grass - (mostly) with cover on - and does approx 180-200 hrs per year. It typically flies at least a couple of times per year - all year round - so maybe that helps it a bit.

However in the past 2-3 months I have begun to think my AH is not 100%. I think it is showing just a little bit of one wing down - when I think they are level. I want to check it out properly with my maintenance firm before looking at a replacement.

If it become necessary, any replacement AH will most likely be solid state.

[cockney steve]

does approx 180-200 hrs per year. It typically flies at least a couple of times per year - all year round

Bloody Norah!!!!! Those are some epic endurance-flights, Lefty!

[alexbrett2]

I think it is showing just a little bit of one wing down - when I think they are level.

I had something like this with the AI in my 1968 Arrow (which as far as I know is the original AI, as no record of any replacements, though the logbooks from the earlier years are a bit vague so can't be 100% certain) - turned out to literally just be that the instrument itself was slightly rotated in the panel (thus while the horizon was actually showing level correctly, the aircraft symbol and pointer indicated non-level as they were not parallel to the wings).

My engineer just had to loosen the screws, align it properly, and retighten - a really quick fix in the end - as such, worth looking at whether the fixed parts of the instrument appear to be correctly aligned with the aircraft axes...

[T67M]

Certified G5 s over £2k plus fitting!

... so it'll pay for itself in about 3-4 years. Sounds like a good plan to me!

[Paul_Sengupta]

They are bog standard R C Allen 22-7

That's where you're going wrong. RC Allen ones don't have a great reputation for longevity in the aviation community. Especially in the US where they have maybe more experience.

[MichaelP]

Why not replace it with an RC Allen 2610?
https://www.kellymfg.com/attitude_indicators.html

I wanted to do this with the Katanas as their horizons are ruined by spinning and the usual training manoeuvring.
Problem was that only one of the two approved horizons was available, and changing it would be a major mod requiring a DAR's sign-off... One of the problems operating school aircraft.
If Diamond had not stupidly specified specific part numbered horizons we wouldn't have to go through the 'Modification' expense.

You would have to detach it from the fallible vacuum system , and fit an emergency battery, but the reliability will go up by a huge margin, and I bet you never have to use the backup battery.

[Oldfart]

Agree Garmin G5s the way to go in our C182. Two fits, HSI and Attitude displays. Removes need of the vacuum system altogether.
Now waiting for the GFC500 A/P to be EASA certified. If the usual excessive EASA delay, probably go the N Reg route.