Maybe someone put the wrong bezel on the AI to make the 172 FEEL a bit faster :-)
While we are all posting puzzle pics of unairworthy aircraft… what is wrong with this pic:
you tuned in different ILS freqs? The Sandels show above glide and the King Crosspointer shows below.
I should have showed the NAV1 & NAV2 frequencies, which were both the same………..
The clue is in the GS deviation.
The clue is in the GS deviation
is there perhaps a two-pin plug that could be connected in the opposite sense? Showing an above GS situation where a below GS would be correct or v.v. ?
is there perhaps a two-pin plug that could be connected in the opposite sense? Showing an above GS situation where a below GS would be correct or v.v. ?
I would guess the same – My king indicator is basically a voltmeter, connect it the wrong way round and it displays the exact opposite of the truth…
How does the Sandel get deviation data? My Aspen installation includes its own resolver (known as the ACU – Analogue Converter Unit), and communicates digitally from the resolver to the screen, so its hard to see how this could happen there.
In modern (that is, Apollo 11 or later) GA avionics, there are 3 ways to get lateral (VOR/LOC) data
There are 2 ways to get vertical (ILS GS or LPV GS) data
In my case, the Sandel EHSIs get composite lateral from the two radios and analog vertical also from the two radios. So the GS can get reversed. Sandel had an error in their IM, on one particular page only. However reversed glideslopes are common in avionics; you just swap the wires to fix it. There are multiple known cases where such aircraft was delivered to the customer. Obviously this is one reason why any flight after major work has to be in VMC, no passengers (except the engineer who worked on it 
) etc.
The KI204 CDI can accept both analog or composite (which it uses) for the lateral, and analog for the vertical. But I knew that would be right because it is wired direct to the NAV2 radio, ex factory. Some other instruments can also accept composite, suprisingly, e.g. the KI229 RMI. Decoding composite is a bit of circuitry involving a PLL. Decoding ARINC429 requires a “computer” 
If I installed a modern GPS, that would output everything via ARINC429. Oddly enough even the old KLN90 did that, but of course that did not do LPV. The 429 will go to the Sandels (it already does for TCAS and heading). If that GPS includes a VHF COM/NAV radio (say a GTN750) then the 429 stream will include the NAV data as well i.e. VOR/LOC/GS. And you throw out a large bundle of wire In fact the amount of wire you throw out when you go to 429 is limited mainly by how much of the cable harness has the cable ties accessible so you can pull wires out…
Then you have a choice of driving the autopilot either directly from the GPS (if it supports ARINC429, as the KFC225 amazingly does, supposedly, though not I believe for LPV which has to be faked to look like ILS) or from the autopilot outputs of the SN3500 which are analog outputs and compatible with just about every autopilot. Both methods will deliver roll steering, which seems to be really just a conversion of the ARINC429 remaining-angle-to-turn info into a roll angle figure. But the latter method will make the autopilot work the same way from ILS or LPV; it knows nothing about any change.
There are also some very new radios which output ARINC429 and I presume they output the VOR/LOC/GS data on that too. I can’t see what else they could output via 429… However how many of those will end up in aircraft that don’t already have a GPS+radio combined unit, is a good question. Castleberry do a version of their electric AI which outputs 429 pitch/roll, and you can get (very pricey) ARINC429 altimeters.
The aircraft is in S&L and at cruise speed. You are pulling on the yok to keep it level (the locking pin holes are not aligned, I think that they lock the elevator at neutral position).
In the C172N (in which I’ve had quite a few hours) the elevator is locked quite nose down. The holes don’t line up in level flight.
If the question hadn’t already been answered, then my cheeky reply would have been… it’s a 172N. This means it has the Lycoming O-320-H2AD. The letters ‘AD’ really do mean ‘airworthiness directive’ in this context, for that engine has a few problems :-)
Sadly the 172N that I learned in and did my (US) instrument rating in was destroyed by a hurricane a few years ago (the hangar collapsed on the aircraft). It was a real work-horse of our flying club, sometimes clocking up 100 hours in a month.
Yes, the N seems to be a problematic proposition, not so much for flight schools clocking away 300-500 hours a year, but for private owners who fly irregularly and maybe 60-100 hours total a year. I have heard of many people seeing premature cam and lifter problems.
However, I tell you that as a renter, somehow I strongly prefer the Ns from the Ps. I know Ps have the advantage of higher MTOW and thus higher useful load (on paper), plus the Ps can be run on Mogas and the Ns can not. But otherwise I think that Ns have a much more pleasant engine sound. And most of them have the 40 degree flaps which are good fun sometimes.
Actually I did like flying our “N” – I’m just glad I wasn’t the one who owned it :-)
Although it flew usually at least 30 hours a month and sometimes up to 100 hours a month, we had one engine not make TBO due to a spalled camshaft (I don’t think it even made 1100 hours). It sticks out in my mind in particular because I was just about to start my PPL solo cross country flights when it turned up on a 100hr inspection (I got checked out on a Beech Musketeer and did the XC flights in that instead, rather than delay my training. I also really liked the Musketeer, but it was a bit thirsty)
