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Maximum TT and SMOH to buy 172N?

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Sam Snead

Roger, Roger.
Aug 8, 2005
I'm in the market for a 172N and I was wondering if any mechanics had recommendations for times I should not exceed on TT and SMOH if I want an airplane that isn't falling apart.

After my research, the average TT on for-sale planes was 5400 hours and the SMOH was 1020.

Airframe condition on a high total time airplane is something that can be assessed in a good prebuy. Book price is lower on a high time airframe so with a little luck you may get what you paid for. I have a Warrior with 8,000 on the airframe and the only "high time" maintenance I've had to do in 6-7 years of ownership is rpelace all the control cable pulleys and other associated hardware. I do not feel 5,400 ours on a 25 plus year old airplane is "high time". Engine time on the other hand is a whole different deal. Time remaining to overhaul is something that you are paying for in the book pricing of the airplane. It is also more difficult to assess the condition of an engine so there's always a possibility that you are paying for something you won't get. If you can crack the nut it's best to buy a runoput and overhaul it. Then you have control of what level of overhaul, the quality of maintenance after overhaul and how the engine is operated. The 172N has the dreaded O-320-H2AD engine that eats camshafts and tappets. That's the bad news. The good news is unlike other Lycoming engines the tappets acan be removed and inspected during a prebuy. An H2AD operated FREQUENTLY and having the oil changed at reasonable intervals may well go past TBO. Charlie Melot Zephyr Aircraft Engines
If one were to buy a 172 with a 'run out', would it not make more sense to simply put a 180 hp conversion on at that time?

You're an expert in this area Charlie. What's the difference in cost between doing a FWF OH on the existing motor vs. buying a factory reman FWF 180 hp and STC?

Taking into account good cores on the existing setup.
I don't have current nmbers on the conversion but FWF of the H2AD with "all the goodies" and no disasters wil run in the $19,000 range. I'll guess at 10K more for the conversion. I'm a big fan of the 180 HP fixed pitch 172 conversion having once owned a piece of Penn Yan but if you don't have an airplane and want a 180 HP 172, buy one already converted. Major the engine if need be. It seldom works out dollarwise to buy and convert.

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