The International Cessna 170 Association

After a new paint job, my mechanic did a reweigh of my 53 170B and it now has a useful load of 830 lbs. When new at the factory, the useful load was 927 lbs. It has an O-300D engine replacing the C 145, but otherwise is a stock airplane. Just out of curiosity, does anyone have any insights about where the useful loads diminish on these airplanes over time ? I obviously thought of the paint versus a bare aluminum airplane, but was just wondering what other's experiences have been. I saw another discussion a few years ago in which one of the fellows said that most stock B model useful loads come in at about " 800 lbs and change ", so mine seems to be typical.

Almost all Cessna 170s that left the factory never spent any time on a actual scale. The CAA allowed Cessna to use representative weights. So the 927 lb useful load could have been in error. That is the start. Most every aircraft I've ever flown, and that is quite a few, has had something wrong with the W&B. And most of these are weighed per regs every 3 years so you wouldn't think that would be the case. Now you look at a 70 year old aircraft that may NEVER have actually been on a scale and wonder why it gained so much weight.

My '49 has NEVER been on a set of scales to this day. My 170, until I did a complete from the factory forward forensic W&B accounting, still had the stretcher installed at the factory, in the weight of the aircraft. It was never removed. There was also an extra radio system still installed. Of course I also found several instances of weight added that was not accounted for. For example it was painted 3 times. It had, and still has cross-wind landing gear.

I suggest that if you spent a few hours, and did a forensic accounting of all the changes to your aircraft from the factory you will understand how your aircraft weighs what it does. The first place I'd look really close, is your AI's last weighing. Many have errors from using wrong arms to mathematical errors.

98C's empty weight was 1358 before the rebuild giving her a useful load of 842, so your current number is in the ball park. I'm betting that original weight didn't include any radios, vacuum system or instruments, or anything beyond the basic 7 instruments required. Probably not even wheelpants. It's not hard at all to imagine a hundred pounds of paint, radios, and instruments.

Thanks Bruce and Miles for your comments and ideas on this. I just find it interesting and was curious about how these airplanes typically change over time from others' experiences. I, of course, thought also of things like the ELT and the vacuum pump on the O 300D, things which weren't there originally. Things like that would all add up in a hurry. And Bruce you are right, a careful accounting of all of the equipment added and removed on 16C since 1953 would tell a lot. I did recheck the math that the AI used and it was all accurate. Anyway guys, thanks for your thoughts, I'm not concerned by it, the airplane is running great. These are sure wonderful old birds. I'm looking forward to Deming in July and doing some hangar flying with all of you. Mike Stahlman

We all get heavier with age .at the last reweigh on my aircraft , I cleaned everything out that was stored under the back seat . Just junk that could come in handy some day . The carpets gain weight also as I weighed the old carpets and then weighed the new carpets and found a 11 lbs difference. The old carpets looked clean but were thicker and had a heap of ingrained gunk in them . The new carpets look great while a little thinner/made differently and the noise difference ,well I can't tell.

Dirt builds up in unseen places. Even freshly-restored airplane rarely are as light at original simply because the repairs/rebuilds include primers and corrosion-proofing the factory didn't. Add the heavier fabrics or leather modern owners want and useful load evaporates.
(The EM McCauley prop that O-300-D uses actually is lighter than the original DM or MDM props.)

It's a great two-place airplane. (And a short-range 4-place.)