Cessna 175 gross weight increase

A

ateamer

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We bought a 1960 175A last week. Great plane, and I’m having fun flying it! It has an STCed Lycoming O-360 with a Hartzell constant speed, GPS 175 and dual G5s - good blend of modern avionics and vintage plane. So, on to my question.

The gross weight is 2350. The -C model from a couple years later has a gross of 2450. I can’t find any reference that describes a structural change, nor any other particular difference besides adding cowl flaps. There doesn’t appear to be an gross weight STC out there.

Anyone have ideas or knowledge about 175s, suggestions regarding gross weight, and maybe a wway to get an increase?
 
Same basic thing happened to the 182. Original 182 had a gross weight of 2550 pounds, rose to 2650 for the 182A, 2800 for the 182E, 2950 for the 182N, 3100 for the 182R. Don't know what was done (if anything) between the models. It may just have been a change in procedures.

Ron Wanttaja
 
wanttaja said:
Same basic thing happened to the 182. Original 182 had a gross weight of 2550 pounds, rose to 2650 for the 182A, 2800 for the 182E, 2950 for the 182N, 3100 for the 182R. Don't know what was done (if anything) between the models. It may just have been a change in procedures.

Ron Wanttaja
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Well for the 172 they restricted flaps to 30 from 40 for go around. OP how’s it fly 100 # over? There’s your answer.
 
ateamer said:
I can’t find any reference that describes a structural change,
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Aircraft gross weights are calculated from not only from structural requirements but performance requirements as well. For example, simply increasing the climb performance can allow for an increased gross weight.

ateamer said:
maybe a wway to get an increase?
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STC.
 
Bell206 said:
Aircraft gross weights are calculated from not only from structural requirements but performance requirements as well. For example, simply increasing the climb performance can allow for an increased gross weight.


STC.
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Well, it definitely has climb performance. This morning at SL ISA +10 at 340 under gross it climbed at 1400 FPM. With full tanks and one passenger the other day and +15 it was doing 1100 FPM.
 
ateamer said:
Well, it definitely has climb performance. This morning at SL ISA +10 at 340 under gross it climbed at 1400 FPM. With full tanks and one passenger the other day and +15 it was doing 1100 FPM.
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I believe the data point would be its climb rate with full flaps. But I would think if the gross weight was a performance limit the engine STC holder would have addressed that in the their option? Perhaps, the O-360 climb rates were not much better than the GO-300 rates?
 
Bell206 said:
I believe the data point would be its climb rate with full flaps. But I would think if the gross weight was a performance limit the engine STC holder would have addressed that in the their option? Perhaps, the O-360 climb rates were not much better than the GO-300 rates?
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Shouldn’t be much different, with only five more horsepower. It is interesting that gross weight increased by a hundred pounds with the C model, but the only significant difference is that the C model had a constant speed prop and cowl flaps, where the previous models were fixed pitch. Mine has a CS as part of the engine STC, so it’d seem to be nearly identical performance.

Maybe - more like probably - the STC developer figured the cost in engineering and testing for a gross weight increased by would not be made up for in sales.
 
ateamer said:
but the only significant difference is that the C model had a constant speed prop
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It could simply be the CS prop that gave a better climb gradient during the C model cert flights? One main reason for using a geared engine with a bigger prop is for climb performance to begin with.
 
It’s a 175. Load it up and go fly. I don’t have time in many planes but the skylark is my favorite so far
 
bonefishpete said:
The Cessna 175 is a light four-seat, single-engine, fixed wing aircraft produced by Cessnabetween 1958 and 1962.
Newest 175 is over 63 years old! I would think any STC and engineering died a long time ago.
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Not at all, people create aftermarket STCs for older aircraft all the time. A friend recently put STC'd aftermarket STOL cuffs and VGs on a 1959 C-170.

If the creator of the engine STC is still around, he would be the person to ask about why it didn't include a GW increase.
 
You might try to contact the owner of the Fresh Pick STC which allows an increase of 150-160 lbs for some of the 182s based on the same concept. Ask how it was researched and maybe you could try to look for the same criteria. It’s just paperwork, like you’re trying to do on your 175.

stc182.com

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An O-360 has much better performance than a GO-300.

A friend is an astute IA, he had a 175 with O-360, if there was a gross weight increase available he would have had it. He didn't.

'59 170, now that is a RARE airplane! HAHA
 
bonefishpete said:
The Cessna 175 is a light four-seat, single-engine, fixed wing aircraft produced by Cessnabetween 1958 and 1962.
Newest 175 is over 63 years old! I would think any STC and engineering died a long time ago.
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Laughs in PA18

Biggest issue is it’s a 175, don’t think there much of a market for investing time compared to the vast 172/182/206/PA28 etc fleets
 
455 Bravo Uniform said:
You might try to contact the owner of the Fresh Pick STC which allows an increase of 150-160 lbs for some of the 182s based on the same concept. Ask how it was researched and maybe you could try to look for the same criteria. It’s just paperwork, like you’re trying to do on your 175.
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I was a member of the Cessna Pilots Association when that effort was underway. A member of CPA was documenting his progress on the forum. My recollection was that they were required to do flight testing at maximum weight. I believe they were allowed to avoid drop testing or other testing directed specifically on the landing gear by using Cessna drawings that showed the landing gear was structurally the same as the models with the 3100lbs MGTOW (instead of 2950lbs). Max landing weight is still 2950 (same as restart models).

I believe the only way the Fresh Pick STC made sense was the vast number of airframes the STC applied to (C182 models with 2950 MGTOW). This is from memory so the exact details may vary. I think trying to do the same process with the FAA now would be even more difficult/longer, but that's just my grumpy old man attitude.
 
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