O-360 Calendar OH Time

can-docan-do
in General Discussion
All,

Looking at a PA-28-180 that was major overhauled 12 years ago. Since then, it's accumulated approximately 500 hours. Everything seems to be in order and to my liking, but I'm nervous that the engine may need either a TOH or MOH. Is there a magic number of hours per year that should put my mind at ease? Should I just assume it needs a TOH out of the gate? Key questions for the owner / for a pre-buy inpsection?

Thanks

Comments

  • flyguydonflyguydon
    That is not real scary. My buddy has a Warrior that has 1800TT airframe and engine. Still runs perfect and makes high 70s on compression. Considerations are like this... Did it sit outside in a warm wet place like Florida... or was it hangered? Dry climate like west Texas, Nevada, Arizona? You want to fly it about 4 or 5 hours and then do a compression test. The 360 is pretty bulletproof. If it is corrosion you are worried about... and you mention top OH as a solution... well, if the cylinders had corrosion I'd bet the CAM does too. The CAM is not corrected by a TOH. 50 hours a year is OK!
  • can-docan-do
    Owner reports compression as one cylinder at 70/80, the rest are >70. It is a Florida plane (I'm a Florida buyer). I haven't been to see it (it's on the other side of the state). The body has been CorrosionX'd and has no corrosion or DH. The one in particular that I'm looking at appears to be undervalued and I guess I'm skeptical of a "good" deal.
  • flyguydonflyguydon
    Where is it? I am near Jacksonville.
  • kwoodworthkwoodworth
    I echo flyguydon's post. Would not assume it needs TOH and would not be overly concerned. 360 is a great engine. My Arrow has 30+ years and 1200 since last OH and is going strong.
    I would rather see 1 hr per week for 52 weeks than 400 hrs in January and nothing for the rest of the year. The idea being to not let the bearing surfaces dry out and continuously wetted with oil to avoid corrosion. Unfortunately that is next to impossible to tell from the logs.
    You mentioned being concerned about a "good deal" Given two identical airplanes, one with 500 hrs and two years since OH and one with 500 hrs and 12 years since OH, the one with 2 years since OH would be valued higher. That valuation is based on the calander OH limit and little to do with the engine internal condition. It is possible that the aircraft you are looking at was correctly valued based on that assumption.
    Best of luck to you, hope that helps!
  • airbusflyboyairbusflyboy
    Borescope the engine, pull off one of the front cylinders so you can get a look at the camshaft ....................... Get oil analysis done after some engine run time. The problem with most of these Lycoming engines is in the CAMSHAFT because it sits up out of the engine oil and is exposed to the air in the engine. I concur that if it was kept in a DRY climate and preferably hangared, it would be in better shape. Engine compression values alone will not tell you what is going on with the internals of the engine. GOOD LUCK, proceed with caution ...................
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