Experienced O300D Shop

How to keep the Cessna 170 flying and airworthy.

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Re: Experienced O300D Shop

Postby GAHorn » Sun Mar 29, 2020 2:47 pm

Aviation Axiom: Climb rates are directly in proportion to Expenditure rates. :lol:
(This thread is diverging from the OT.)

TSRamsey: WHAT does your mechanic mean by “increasing metal”?
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Re: Experienced O300D Shop

Postby 170C » Sun Mar 29, 2020 4:30 pm

I think the O300 series are good engines. They are smooth, reasonable maintenance, reasonable fuel consumption (and most leak :wink: ). We have to recognize that its maximum output is 145 hp (on a good day) and not 160, 180, 200, etc. I think a lot of us wish we had more power, faster speed, greater gross weight,etc. and all that is available for $$$$. If we can bring ourselves to operate our planes as they were designed we will be in good shape.
I still don't understand how some engine conversions permit greater gross weights without any structural modification.
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Re: Experienced O300D Shop

Postby GAHorn » Sun Mar 29, 2020 6:48 pm

170C wrote:I still don't understand how some engine conversions permit greater gross weights without any structural modification.


What engine conversion are you thinking of that permits a gross wt increase?
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Re: Experienced O300D Shop

Postby 170C » Sun Mar 29, 2020 10:01 pm

Air Planes in Wellington, KS has vrs STC's for engine upgrades. One of my friends here has a "60 model 172B that has their Lycoming O-360, fixed pitch, 180 hp conversion. It has either a 200 or 250 lb gross wt increase. Another friend has a C-180 with their conversion and he says it also has a wt increase. I don't recall how much. I have seen advertisements for other conversions that claim gross wt increases. I can't figure out how that is possible without some structural modification.
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Re: Experienced O300D Shop

Postby ghostflyer » Sun Mar 29, 2020 10:09 pm

The 170a and the 170b airframe is over built . The early 180,s have many components of the airframe similar to the 170. Another example would be the Cessna 175 with the geared o-300 engine pumping out more power. We have a compulsory SIDS inspection program [in Australia and many countries of the world ] for all Cessnas regardless of their operation and this was a big learning curve for all on hidden metal fatigue ,corrosion and damage to airframe due to rough operations and where the aircraft was operated . Each 100hrly/SIDS inspection here in Australia very close attention is especially made to the firewall ,engine frame mounts and the tail feathers. These inspections covered x-rays and eddy currant of the major or critical components .There has been a number of aircraft that have been scrapped as it wasn’t economically to do the repairs. The number of owners thought that the 100 hrly was the end all of inspections had a rude awaking when confronted with the evidence .
PS. I do not know of any STC,s that allow a weight increase for the 170 series due to change in engine . The STC holder would be put through the ringer to get a weight increase . It wouldn’t be cost efficient for the STC holder to go down this path. Getting a change to the type data certificate for a aircraft of this age would be impossible . [IMO]
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Re: Experienced O300D Shop

Postby GAHorn » Mon Mar 30, 2020 2:03 am

170C wrote:Air Planes in Wellington, KS has vrs STC's for engine upgrades. One of my friends here has a "60 model 172B that has their Lycoming O-360, fixed pitch, 180 hp conversion. It has either a 200 or 250 lb gross wt increase. Another friend has a C-180 with their conversion and he says it also has a wt increase. I don't recall how much. I have seen advertisements for other conversions that claim gross wt increases. I can't figure out how that is possible without some structural modification.


Frank, those “upgrades” are not without structural modifications. From the Air Plains website: “ The gross weight increase for 1963 through 1967 (172D-H models) require a one-time installation of three stringers in the tailcone. The stringers were added during production of the Cessna 172s during 1968 timeframe. Prior to purchasing the gross weight increase with the 180HP upgrade confirmation of the stringers installed is required. 6 Ply tires are also required if not already in place.”

What is often conveniently over-looked in claims of wt increases is the reduction in performance sometimes required. Example: Later Cessnas had wt increases...but did so at the expense of flap-deployment because the rear doorpost cannot handle the increased weight. A reduction of flap deployment reduced stresses at the rear doorpost and also lengthened landing distances.
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Re: Experienced O300D Shop

Postby c170b53 » Sun Apr 19, 2020 3:22 am

Just a follow up to what I tried to describe earlier in the post.
EA867484-0721-406B-9AB8-1DB23E5CFDDC.jpeg
I believe It’s a possible source of vibration in high time Continentals.
Here’s the crank flange for one of the two counterweights
207D8B61-699D-483E-9803-6BB99430D0BD.jpeg

Shinny spots and the beginning of metal deformation is where the counterweight has contacted the crank, probably not a good thing in the long run.
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Re: Experienced O300D Shop

Postby GAHorn » Sun Apr 19, 2020 10:36 am

Jim’s pics demonstrate (just) one of many reasons prop strikes require an engine tear-down. Even a minor strike can damage. So-called “mike-ing” or “Mic-ing” runout of the prop flange is not valid procedure.
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