C-172 Checkride.

[sennadog]

I've got a check ride in a C-172 tomorrow and I want prepare for it so I've got a few questions.

I've only flown a Katana DA-20 up until now which has variable pitch, electric trim, stick etc.

Having had a brief look at the C-172 it looks a bit old fashioned compared to the Katana (no offence) so I was after any tips that you guys had in order to make the transition bearing in mind that I only have 50 odd hours.

1) The yolk looks very odd to me and whilst it will probably be intuitive are there any differences compared to a stick?

2) The whole mixture control looks a bit of a mystery to me. Is it some weird black art?;)

3) Any clues as to the knob that works the trim?

Obviously, the whole point of the check ride is to sort this lot out but any tips that you may have, particularly going from a Katana type to a Cessna type would be of interest.

[Keef]

The yoke (yolk is the yellow bit in the middle of an egg, not dissimilar to some C172s) is a non-event, or I found it so after transitioning from a pole.

Mixture control - leave it at fully rich once you've started the engine. When you get to cruising altitude, you'll have time to pull it back a bit. You need to consult the POH for your particular one to find out what technique to use - depends on what gauges you have. Not difficult.

Trim knob: if it's the one half way down the centre console, it works in the obvious sense: UPWARDS to trim nose high.

I converted to C172 after about 50 hours, and had no trouble with the controls. I needed about 7 circuits to get the feel of it and be sure of flaring it OK onto two wheels...

[Tinker]

The newer ones have a tendancy to float (compared to the 1970's versions), and I think that they also have a vernier mixture control so you can make fine adjustments to it by turning anticlock to lean and vice verca. This helps when leaning as you can quickly get a ball park setting for it ie x turns anticlockwise.
All in all it's a very civilised aircraft to fly and a good starting point for moving on to the other varients like the xp/rg and Riems Rocket which I really enjoy flying and are extremely compitent machines for traveling around in.

[FlyingCesspit]

Just to clarify, the trim "knob" is actually a vertical wheel, in the middle below the panel.

As has been mentioned, the 172 does tend to float a lot after the flare, and keeping your speed right is critical. When I did my IMC rating, the instructor suggested I approach at 65 kts on final, 60 kts over the threshold (5 knots slower than I was used to) and this made the plane a lot easier to land.

I haven't flown a Katana, but on converting from a C152 the main differences I noted were the float and that the controls were a lot heavier.

On the mixture control, I rarely move it away from rich in flight as I'm usually below 3000' and so the benefit is minimal (and keeping the mixture rich also cools the engine somewhat). However, the newer fuel-injected engines need some juggling with the mixture control to get them started, and you'll need briefing on this. With the older carburettor engines you can basically leave the mixture rich from cranking the engine to start it right through to when you want to shut the engine down (mixture lean, throttle out).

Correct mixture leaning will save a few percent on fuel consumption and maximise power output, but general advice is not to bother below 3000' QNH.

As mentioned, the newer 172s have a screw thread on the mixture control, so you can turn the mixture control as well as pulling it out/pushing it in. This gives you better control over the leaning process - on older 172s I was always afraid that I'd pull the control out too far by mistake.


The 172 isn't the most sexy looking of aeroplanes, but it is a safe, strong, reliable machine. Enjoy!

[EI_Sparks]

You can leave the mixture at rich all the time - trouble is you're wasting a lot of fuel (I can't find the reference, but I remember seeing it quoted as 18gph versus 12gph), losing power (again I can't find the reference, but I remember it being up to 20-25hp from a IO-360) and abusing your engine, reducing it's lifetime (fouled spark plugs, exhaust valve guide wear, stuck exhaust valves, etc.). You only have mixture at full rich on takeoff because (a) the engine is aircooled and that's insufficent cooling for the cylinder heads if you're drawing maximum power and sitting still (as you are at the start of the takeoff roll); and (b) (and this is the "real" reason) it prevents detonation at a point where you really don't want anything to go wrong with the engine!
Avweb has a really good article on mixture here (http://www.avweb.com/articles/pelperch/pelp0018.html).

Mind you, I am still surprised at the conservatism of GA - don't get me wrong, a stearman is an awe-inspiring aircraft to look at and I would give a lot to own one (If you want to show some skeptic why aircraft are beautiful things, show them a stearman!) - but most GA trainers seem to be 1970s spamcans with 1940s engines! As that Avweb article points out, you can't run your engine at peak efficency because of it's design and because you normally don't have enough instrumentation. One of the nicest things about the Katana (and one of the best design decisions IMHO) was that they got rid of the mixture control :) :p I just want to know where are the powerplants with all-electronic ignition (magnetos? you're kidding, right? sheesh!), FADEC (if I can't manage mixture optimally on a flat-four, why would I want to try?) and why aren't there more small cheap turbines around? :) :rolleyes::rolleyes::rolleyes:

[BayAreaLondoner]

Senna - I did something similar last year. These are my observations:

Taxiing
The Katana seems to make tighter turns. However, in the C172, it is very tempting to attempt to steer with the yoke. Whilst learning to fly in the Katana, I felt no such temptation because of the stick. Ironically the student learning in the C172 gets over the desire to steer with the yoke pretty quickly.

Feel
The Katana requires a very light touch. By comparison, the C172 doesn't. In my experience, it won't float anywhere near as much as a Katana. You may find that your landings are "flat" in the C172 because you're so used to the lighter control forces of the Katana.
I found the C172 much more "nose high" than the Katana, and being short torsoed I think that a cushion will improve my landings.
Stall characteristics are different. The nose really drops on a 172 compared to the Katana.
Whereas all the Katanas in the fleet I have access to fly about the same, the same is not true for 172s, especially if they are of different years. This is more something to be aware of than anything else and it might be useful to take a different one up with a CFI once you feel pretty comfortable in the first one you try.

Trim
Trimming is different, but you'll get used to it. I never found that the electric trim on the Katana was that great and really used it mostly in cruise. In the 172 I'll trim during all phases of flight. That's about all I can say about that.

Mixture
The mixture control is initially a non-issue unless you're operating at high DA or are going on cross-countries immediately. Obviously you need to know how and when to use it before you are checked out. Use the vernier (twist) during flight (i.e. don't pull it out to lean the mixture while you're flying). Also note the correct engine shutdown procedure.

Perhaps I'm demonstrating my own lack of ability but I'd count on about 5 hours of dual before you're checked out. YMMV.
I have to say that once I got checked out in a 172 I haven't flown a Katana since... Perhaps that's due to the hourly rate being the same where I rent and that I usually take more than one pax. It is a shame because Katanas are fun to fly. The shiny new DA40 we have looks nice but at 1.75x the price of the 172 I don't think I'll bother getting checked out in it.

[FlyingCesspit]

Sorry, EI_Sparks, I just don't accept your first para. Typical fuel burn for the latest 172SP with 180HP engine is 9gph - you can get up to 11.1 at full power at 20 degrees C below std. temp. The older 172s with 150 & 160 HP rubber bands will burn 1-2 gph less.

According to the 172SP Information Manual, using an extreme fuel saving regime (i.e. leaning above 3000' for full-throttle climb, leaning at all altitudes at less that 75% power, and leaning on the ground before take-off) "... can provide fuel savings in excess of 5% when compared to typical training operations at full rich mixture". Hardly a big saving. It's really cruising at higher altitudes that you are going to notice the difference.

The manual agrees with you about the reduction in plug fouling, which arises from the lower fuel flow rate and hence lower tetra-ethyl lead flow. But at low altitudes you don't reduce the flow much by leaning.

The bottom line for me is that various instructors over 25 years have advised not to bother about leaning on 152s/172s below 3000' altitude.

[EI_Sparks]

FC,
No need to apologise :) I found the reference to the 18-to-12-gph figures and it wasn't where my memory said it was - it was to do with liquid cooling of an O-360. It's here (http://www.liquidcooledairpower.com/lc-betterperformance.shtml) if you want to look at it - nothing to do with mixture control though, and they are trying to sell you their stuff so a) pinch of salt needed and b) BRL will probably cut it out soonish - sorry BRL, just wanted to show the number wasn't made up! :rolleyes:

On the other hand, I don't believe that 5% figure (it sounds too good to be true) - as BAL said, 172s have "personalities" :D and I'd want to see the actual measured figures (and you'd need a fair few instruments to get valid data) and even then I'd only believe 5% on that particular 172. Not too fussy, me. :D

Erm, as to reducing plug fouling via lead ... lead doesn't reduce plug fouling (as far as I know anyway). It slows the combustion process to help prevent detonation. Read this (http://www.avweb.com/articles/pelperch/pelp0055.html) .

The "full rich to fly, full lean to shutdown" rule will work - but it's very low on finesse. Okay, if you're learning, don't worry about it - you're learning to fly, not manage the engine. :) But that doesn't mean that you should just forget about the engine forever - and unless money and downtime are of no consequence, operating at full rich all the time is probably not the best procedure. Of course, if you don't have sufficent instrumentation on the engine, this is all rather academic. :) And of course, standard disclaimers apply - this is PPRuNe, not your operating manual, so if you lean on the ground but don't lean enough and then try to takeoff and mangle your plane - well, tough on you! :eek: :eek:

[Circuit Basher]

Good topic - I'd go with the 'Don't bother to lean under 3000 ft' brigade, but would suggest that you're actually in a straight and level cruise at 2,500, it may be worth doing! If you've got lots of turning points, are just on a quick 1 hr local flight where you're just mooching about or are in lumpy country where you may need to do some 'jinks' to avoid cumulus granitus, then I'd leave it full rich.

One club I used to belong to where the CFI was paranoid about reducing fuel bills for his C150s and told everyone to lean to the minimum got a nasty shock when 2 out of 4 of his training fleet suffered premature engine failure due to burnt valves. The suggestion from the engineer was that they'd been run over lean and had consequently been prone to overheating the engines.

Don't be smug, though - running overrich tends to wash the oil from the cylinder wall and increase cylinder wear!!

[flyboy6876]

Sennadog

How did the check ride go?

I've just finished my endorsement on the C172 and it found it a delight after many hours in the C152.

I found having the rudder trim a great bonus, but held of using it for a bit so that I could get used to the extra input required on the rudder in comparison to the C152.

I found once I'd got to recognise the engine sounds, leaning the mixture came fairly easily just by winding back and then a couple of turns forward once the engine starting running rough.

The C172 does require quite a lot of round out in comparison to the C152 and my first few landings tended to be 3 pointers
:( , but once I got the "picture" I have found this aircraft easier to land.

Given your other posts on travelling to RSA for a holiday, the C172 is a great aircraft for this environment. I've spent many hours "jollying" around the Eastern Transvaal in a C172 with my mate. We landed at some of the private game reserves and found that the C172 handled the grass (almost waist high in summer) fairly well. The dirt strips also proved no problems.

[EI_Sparks]

CB,
Not surprised at the over-leaning story - like the avweb columns pointed out, with the lycomings you need a serious amount of instrumentation (Deakin keeps recommending an engine monitor) because the four (or six) cylinders don't all hit peak EGT at the same mixture setting since the cylinders aren't all getting the same mix. Flyboy's method is about the best you can do without instrumentation I think. Unless of course you've got a radial up front, in which case you can lean according to exhaust colour. I still think we ought to move to gas turbines mind you :D

[sennadog]

Ooer. I can't say I'm overly fond of the C-172 at the moment partly due to the sheer brilliance of the Katana and partly because it's my first time out in a new type.

First impressions were that it's like stepping into a time warp with the controls all over the place - why are the flap controls all the way over to the right?

The throttle control felt really weird and counter intuitive for me as I kept pushing it forward to reduce power and that trim wheel is massive!:p

As flyboy6876 correctly surmised the reason for the check ride is because this is what I will be using on holiday but it feels like a tank so it is definitely up to my rough handling and should cope well with bush strips.:D

Generally, the controls felt very heavy and it is less "flighty" than the Katana so I did feel that it was easier in the circuit to maintain height and it was less prone to being knocked about by wind shifts so from that point of view it is better. The range from the two tanks is impressive as well but I have to do some more circuits until the check ride is complete and I feel happy flying it in general.

Lastly, many thanks for some excellent advice from you guys. Pretty much all that you said applied and it is a testament to PPRuNe and the people on this board that make it such a great place for advice.

Cheers All.:D

PS. The Stick v Yoke debate..........

Sticks Rule!:D

[SKYYACHT]

Senna,

I agree with you ref sticks!!!!

You will find that the flare needs to be made much more positively on the C172 (due to the extra bank of cylinders 6 as opposed to 4) to prevent the nose from landing before the rest of the metal.....

I gotta admit, time warp is correct. As I have said to you before, I wouldnt bother leaning under 3000 as its a bit pointless for the amount of ecnomy gained. (Remember the performance charts also emphasised correct leaning being used above 3K.

All in all you have been spoilt my son, using a DA20......Now u must learn to fly again.....No worries - have fun...they arent that bad.


Cheers.

Tailwinds and blue skies.

[EI_Sparks]

Senna,
Nooooooooooooooooo!!!!!! Leave those aluminium spamcans behind and go back to a real aeroplane!! :D :D :D :D :D

[BayAreaLondoner]

Senna,

Felt the same way as you did mate when I got checked out in the 172.
Thing is though, it is so much more useful to me than a Katana and doesn't get as hot in the summer. I can actually take 2 (possibly 3) friends with me, and therefore lower my cost of flying. I can do instrument training, etc.
Don't get me wrong, the DA20 is loads more fun but it just isn't a very useful airplane. I'd never own one other than for leaseback to a school, where presumably I'd make more money than on a 172 because the running costs are supposedly lower.
Now the DA40 looks like a much better proposition...

[sennadog]

Hehe. Bit of a Katana fan club here. I'm going to learn how to fly the C-172 and keep relatively current on it, ramping up the hours prior to any flying holiday and using it for trips to Le 2K as and when........

until

I've got 100 hours. The club inisist on 100 hours as a minimum before the DA -40 can be flown and apparently, if anything, it's a bigger, nicer version of the Katana.

Can't wait.:D

[BayAreaLondoner]

I'd be interested in knowing how the going rate of your DA40 compares to your DA20s.
Ours is v. expensive in my opinion, although it is brand new obviously and full of the latest kit. The DA20s go for $85/hour and the DA20s are at around $140/hour as I recall. By comparison, the C172s are $85/hour as well.

[EI_Sparks]

*COUGH* you get what you pay for*COUGH*
:D:D:D:D:D:rolleyes: :rolleyes: :p

[sennadog]

DA - 20 @ £95.00 wet.

C - 172 @ £108.00 wet.

DA - 40 @ £120.00 wet. But then it is quicker.:D

[BayAreaLondoner]

Hmmm... hadn't realised that the DA40 cruises at 147kts, which is more comparable to the 182T that we have, which goes for $10/hour more than the DA40 and requires a complex endorsement.
Similar useful loads with fuel as well. Maybe I should get checked out in that DA40...
Senna - I too have heard it flies very similarly to a DA20.