PA28 AI Question

[jayemm]

We've got problems with the AI (Attitude Indicator or Artificial Horizon) on our PA28 Warrior II. We're told that to replace it is almost impossible because the 'hole in the panel is too big for AIs that can be obtained now'.
Not being an engineer, I'm puzzled as to why fitting a new AI into a PA28, one of the most popular (some might say 'common') aircraft around is such a problem.
Can anyone offer an explanation or information?

[Fuji Abound]

I can only hazard a guess - it might well be wrong, and I am sure an engineer will be a long.

The "problem" with after fit equipment is often that it has not been type approved by the manufacturer. This can mean the only way to fit a perfectly good item of equipment is to apply to the CAA for a minor mod. Obvioulsy this means parting with some additional cash and of course it must be a mod they will approve.

It would seem surprising if that aplies in your case.

Subject to the afore surely it would be possible to fit a blanking cover (simply a plate riveted to the back of the existing panel) with a suitable sized whole cut for the more modern AIs. You could even use it as an opportunity to fit a more reliable electric AI.

[david viewing]

Obviously no idea what's in your panel but are you sure this (http://www.adamsdirect.co.uk/proddetail.asp?group=Instruments&modelno=RCA22-7) from Adams Direct (http://www.adamsdirect.co.uk/prodguide.asp?grp=Avionics-Installed) won't just fit?
Alternatively, don't forget Ebay. It's amazing what you can find, often changed out by avionics shops upgrading panels and complete with yellow tag.
If your engineer is being funny about you buying new or used equipment, you might want to talk to David Jones at Airspeed Aviation (http://www.derbyaeroclub.com/).

[TheOddOne]

You could even use it as an opportunity to fit a more reliable electric AI.

I'm not sure I like the idea of an electric AI if the only other horizon instrument (turn & slip) I have is also electric. The advantage with a vacuum-driven AI is that you not only have 2 completely independent power sources, but the TYPE of power is different, too, making the simultaneous failure even more unlikely.

Is getting the existing item rebuilt not an option? It might only be out of teh aircraft for a couple of weeks, just fly in good weather during that time. Presumably you'll still have the turn & slip 'just in case', to enable you to do a 180 if you do happen to go IMC.

Cheers,
TheOddOne

[A and C]

This sounds to me that there has been a mis-understanding between your selfs and the engineers.

I can only think of two types of AI that are likely to be fitted to your aircraft and both types are avalable, new or OHC.

It is very unlikely that someone would have fitted an AI that was not one of the two "standard types" so I would advise that you talk to your engineers face to face and get this sorted out, if you have any more questions take a photo of the AI and the hole in the panel, email them to me (with a rule in the photo for scale) and I will try to offer some more advice.

[spernkey]

JUST BEAR IN MIND THAT MANY ENGINEERS ARE C*** WHEN THEY HAVE SOMETHING AWKWARD TO DO EVEN IF IT IS A CHEAPER SOLUTION FOR YOU!
IF YOU VALUE GOOD MAINTENANCE DON'T DELAY GO TO DERBY TODAY!
YOU WON'T GET SPIT AND POLISH BUT YOU WILL GET A GOOD JOB AT SENSIBLE MONEY. i'M BIASED - BUT THEN THEY DID SAVE ME FROM DYING IN 3 OF MY PREVIOUSLY BADLY MAINTAINED AEROPLANES.:ok:

[smarthawke]

I'm a bit confused by this - all the standard vacuum DIs and AHs (AIs if you like) are a standard size, or at least the face is.

If your aircraft has King AH/DIs fitted (as part of the KAP100 autopilot for instance) then the hole in the panel may be larger because they have a stange shaped face.

If you do have autopliot feeds of these instruments then you have to have that one fitted if you want the autopilot to work.

If you don't want the autopilot then just have an 'adapter' made up so that a standard instrument will fit in the non-standard hole. It isn't exactly rocket science!

Have you had your one removed and sent for repair/assessment? Try IAE at Cranfield (01234-750661). They'll tell you if yours is repairable.

Unfortunate thing is the King AH/DIs are twice as expensive as a standard one because of the autopilot feeds. Ask me how I know....!

[Davidt]

In your boots I would;

1 Look on the Piper owners group web board ( I believe that there are at least two Piper owners groups maybe more for specific types) beyond question someone will have had the same problem and will show you where to get a new or overhaul.

2 Do a web search on the part number there will probably be a 1/2 dozen places in the States that will sell you a replacement which will be STC'd or an oem replacement or overhaul

3 Ask Spruce,Chiefairparts,Wagaero or Central Oregon via their web sites.

My experience is dont bother trying to get it fixed in the UK the chances are the place you take it to will send it to the States anyway and you will be charged accordingly.