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Old 10th Aug 2010, 00:22   #1 (permalink)
 
Join Date: Apr 2004
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POH: C172N vs C172P

I fly a C172P and have been searching for ages somewhere to get hold of a .pdf POH so that I could print off the take-off/landing performance charts and W&B charts to use in pre-flight planning. No such luck! There's no photo copier at the airfield I fly from, and I'm not allowed to tke the POH home

I have found plenty of C172N POH's avaialable for download on the internet, and have printed one of these instead. I notice there are slight differences in the max/useful loads (less than 100 lbs) and the fuel capacity along with various speeds in both models appear to be exactly the same.

If I'm using a C172N POH is there anything I need to watch out for as being majorly different from the C172P that I'm actually flying? Of course I understand that I can't take the C172N figures as being 100% correct, but would most people agree that the figures will be close enough to not have much cause for concern?

Many thanks in advance
stansted_dan is offline   Reply
Old 10th Aug 2010, 00:30   #2 (permalink)
 
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I use something called Google, it's real useful.

Found this, looks as though it's for flight simming (?) but based on the real POH, you'll need to check it out for accuracy.
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Old 10th Aug 2010, 01:00   #3 (permalink)
 
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SkyHawk-N, believe me I was on to the 15th page of search results on Google but the only official POH's I could find were C172N's!

I did come across the one that you have linked, but without going through every single figure in the entire manual to verify it's accuracy I think I'd rather trust an official Cessna document.
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Old 10th Aug 2010, 01:01   #4 (permalink)
 
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The significant differences between a C172N and a P are as follows

1) engine: N has a lycoming O320 H2AD vs P with a O320 D2J, but both are rated at the same 160 hp

2) GTOW: N gross weight is 2300 lbs vs 2400 for the P

3) Maximum flap: N flaps go to 40 deg vs only a maximum of 30 deg on the P

All performance charts for an N will work on a P if the aircraft weight is at or below 2300 lbs. The only difference is the short field landing distance figures for the N are predicted on the full 40 deg being available and so the P will require slightly longer distances. However IMO if the the field lenght is so close to the numbers that this becomes significant than I would suggest one should not be attempting the landing in the first place ( BTW, I tell my students that book landing and takeoff should be increased by 50% for actual use)
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Old 10th Aug 2010, 03:58   #5 (permalink)
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Dan,

I often (to copyright dismay, I expect) digitally photograph pages of interest from such manuals, when I cannot take them away to copy them otherwise. A good digital photograph will be darn near as good as a photocopy, and with a bit of cunning, can be scanned, "OCR'd" and turned into a text document if need be. With a bit of hunting, you might also find a genuine factory training flight manual for the model of aircraft of interest. It will be as effective as the real one for this purpose.

Although as Pistons suggests in this case, substitution from another model would mostly work, this is generally not a great idea, there are subtle changes sometimes. I do buy manuals off ebay from time to time.
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Old 10th Aug 2010, 05:32   #6 (permalink)
 
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Essco are probably one of ther better places to buy manuals. Here is the 172P pilot information manual.
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Old 10th Aug 2010, 06:45   #7 (permalink)
 
Join Date: Apr 2004
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Thanks for the informative replies gents.

Pilot DAR, that's a very good idea with taking photos of the relevent pages. I have a 12MP D-SLR so I guess that a full resolution photo on that with a bit of cropping/editing I should then be able to turn that in to a fairly good copy.

SkyHawk, I will try the idea above next time I'm at the airfield and if not give your link ago to just purchase a real one!

In the meantime I'm currently trying to plan a trip for this weekend - would you say that aslong as my 172P is no more than 2300lbs and the take-off/landing performances for the 172N work with a lot of room to spare (say >20% once all the other factors of grass, headwind, 1.33 x safety factor are worked out) that I should be ok? I guess that if my margin is less than 20% then the figures are a bit too close for comfort, and I could do with driving up to the airfield and sourcing the actual POH just to be sure.
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Old 10th Aug 2010, 07:31   #8 (permalink)
 
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stansted_dan, check PM.
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Old 10th Aug 2010, 13:36   #9 (permalink)
 
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Stansted_Dan,

If the club won't let you take the POH away, and there's no photocopier, just take in a digital camera and photograph the pages you want.

Brooklands
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Old 10th Aug 2010, 15:01   #10 (permalink)
 
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I'm probably stating the obvious, but make sure you're using the correct empty weights etc., for your particular a/c. They'll be different between different P's, let alone P's and N's..
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Old 17th Aug 2010, 02:56   #11 (permalink)
 
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This is probably what you're looking for.. a weight and balance Excel spread sheet for the C172P model. Seems like the main difference between the N and P series is the Max weight. It's been supersized from 2300 lbs to 2400 lbs.

http://austingwatson.com/aviation/CH...WTBALC150M.xls

Note the Excel spreadsheet has three sheets, C150M, C172P and C150M Austin SOLO. Select the C172P sheet as per your requirements.
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