172M 180HP conversion

[cleared4theoption]

So I know that it is fairly common to take an older 172 with the 160HP O-320 and put the 180HP engine in it. Obviously performance specs like V speeds, takeoff and landing distance, Max gross weight as well as weights and balance would be affected. If someone does this to their plane, are the new specs required to be placed in the POH? Especially if it is a rental plane?

 

[RyanShort1]

So I know that it is fairly common to take an older 172 with the 160HP O-320 and put the 180HP engine in it. Obviously performance specs like V speeds, takeoff and landing distance, Max gross weight as well as weights and balance would be affected. If someone does this to their plane, are the new specs required to be placed in the POH? Especially if it is a rental plane?

I don't know of a requirement for the specs to be placed in the POH, but likely the STC paperwork will be required to be in the aircraft. If it's not in the aircraft...

Ryan

 

[BiffJ]

Basically you would comply with whatever the specs are in the STC you use to do the conversion. If the STC says to add pages to the POH than you do. If it just changes some of the red, yellow or green zones on the gauges than you do that.....follow the STC. If you're doing a Field Approval(good luck with that) then you do what the FAA GADO (FSDO?) office engineer or inspector tells you.

Hope that answers the question

Frank

 

[BillTIZ]

So I know that it is fairly common to take an older 172 with the 160HP O-320 and put the 180HP engine in it. Obviously performance specs like V speeds, takeoff and landing distance, Max gross weight as well as weights and balance would be affected. If someone does this to their plane, are the new specs required to be placed in the POH? Especially if it is a rental plane?

Dependent on the STC, the Max GW may not be affected, nor would the Va, Vno or Vne.

The STC may require additions or changes to the POH for engine operations, fuel flow and the Takeoff and climb data.

 

[W. Stewart]

I have that issue with the IO-550 "upgrade" to my (de-)T210N (formerly TIO-520). Now I have 300HP continuous, while the T210 POH figures are based on the 310HP for 5 min, then 285HP.

I am not concerned with cruise numbers, although that data has been changed in the POH. I am mostly concerned with takeoff data. If my takeoff figures are marginal, I refer both to the takeoff data for a T210N and a NA 210N and and go with the most conservative numbers (and even then add a 50% margin).

My technique may not help you, as Cessna did not produce both versions of your plane, so different Information Manuals are not available.

Wells

 

[AuntPeggy]

When we bought our 172M 180hp, there were no changes to the POH. We found new numbers in the aircraft logs and made a note for ourselves in the back of the POH and especially on the kneeboard.

When I took my PPL checkride and it came to that part of the Oral where the inspector changes the weight carried, expecting to require a rebalancing of the load, I showed him the numbers and then offered to "pretend" to rebalance using the 160 hp numbers. He declined saying that the test was to use the existing aircraft.

Anyway, I believe you are not required to change the POH in that era aircraft. For younger aircraft, I think there is a different set of rules.

 

[cleared4theoption]

Thanks for the replies...the context of the question was more from a renter/student perspective. For example, I know the pattern speeds and the v speeds on a standard 172M...but I wasn't sure if the new engine would change those, and if there was a reg requiring that new info to be put somewhere in the plane.

 

[jjflys]

I've flown/rented 172N's with 160 and 180HP. Functionally I do not fly them differently- I fly the same v-speeds and approach speeds. The nice thing is with 180HP you have a higher gross weight to play with and better climb performance at Vx and Vy. I did see the STC paperwork for the 180HP conversion and all it mentioned was the change of max gross....

 

[Skylane81E]

So I know that it is fairly common to take an older 172 with the 160HP O-320 and put the 180HP engine in it. Obviously performance specs like V speeds, takeoff and landing distance, Max gross weight as well as weights and balance would be affected. If someone does this to their plane, are the new specs required to be placed in the POH? Especially if it is a rental plane?

V speeds are the same, as they are affected by the airframe more than the engine. W&B will change if the engine is heavier.

Up gross on that plane doesn't come with just the bigger engine, IIRC there is also a flap limitation.

the STC paperwork will tell you what needs to be in the plane. Probably not much. The STC holder can always just say the performance is atleast as good as the unmodified plane and call it a day. Many do.

 

[poadeleted20]

Thanks for the replies...the context of the question was more from a renter/student perspective. For example, I know the pattern speeds and the v speeds on a standard 172M...but I wasn't sure if the new engine would change those,

Not significantly.

and if there was a reg requiring that new info to be put somewhere in the plane.

No. As long as the performance of the modified aircraft meets or exceeds the original, there is no requirement to develop new performance data.

 

[Pilawt]

Here are the supplements we got when we bought the Air Plains 180 hp conversion for our C-172N. Notice that there are new V-speeds listed, and new weight-and-balance data. There is also a new power chart, but unlike the Cessna manual, no cruise speeds are listed. As Ron said, if the performance is equal to or better than the original, no new data are necessary. But with the heavier gross weight, landing distance will be "worse" than before, so a new landing distance chart is provided.

Max gross weight as well as weights and balance would be affected.

Max gross weight is usually increased with the 180 hp modification, but not always. In our case, the 180 hp modification is one STC, and MGW increase (permitted by limiting flap travel to 30 degrees) is another. An owner can do the former without the latter, and wind up with a powerful airplane with 40 degrees of flap but lower useful load. So especially with a rental, you have to check the paperwork to be sure what you're dealing with.

 

[DouglasBader]

I've towed banners with 180 hp 172's. They don't have the pull of a Pawnee or 182, but they do okay. 180 hp is an improvement over the stock 0-320.

 

[swingwing]

I reference a 172Q poh for preformance data for my Airplanes 172M