Poll: Are you over or under 170lbs?

[Ravioli]

6'0" and 148lbs Pretty much the same since high school (early 80's)

 

[SkyHog]

Ok, now look at part 25 airline transport certification rules.

http://www.ecfr.gov/cgi-bin/text-id...831ed5e8&mc=true&node=se14.1.25_1785&rgn=div8

(f) Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant, seat, safety belt, and harness for each relevant flight and ground load condition (including the emergency landing conditions prescribed in §25.561). In addition—

What does that tell you? That says to me the seat and belts holding a very overweight person is likely to collapse in a crash. (I'm not an engineer nor have I ever worked for a seat manufacturer)

You are adding too much opinion there. Without exceeding the test as a separate test, there is no way to determine what is likely to happen. It is just as likely that the seat can hold 600lbs without issue.

 

[Jim_R]

Thanks. That's quite different from what you wrote initially:
<snip>
The quote from Piper only addresses its crash-testing. It says nothing about 170# being a limit, nothing about not exceeding it, nothing that would suggest "test piloting".

And yet it's true; there were multiple communications with Piper and I didn't include all of them. Here is the first one that more clearly references the 170# limit:

Dear Sir:

Our seats are rated to 340 lbs. total /170 lbs. per seat with a safety factor of 1.5 minimum per the FAA regulations in force at the time of certification. Piper Aircraft does not recommend that these numbers be exceeded. It is also important to take into consideration that the aircraft must be kept within the CG envelope when loading in order to ensure safe operation of the aircraft.

Piper recommends that our aircraft be operated per the most current AFM/POH for the aircraft by serial number and model, remembering that it is the responsibility of the Pilot and aircraft Owner to ensure that the aircraft is loaded and operated properly.

Regards
Technical Support/Airframe
Piper Aircraft, Inc.

 

[OrangeCountyAviation]

6'0" and 189, with a goal to get back down to 175.

 

[FlySince9]

I haven't seen 170 since 1974...

 

[acrophile]

there were multiple communications with Piper and I didn't include all of them. Here is the first one that more clearly references the 170# limit:

Our seats are rated to 340 lbs. total /170 lbs. per seat with a safety factor of 1.5 minimum per the FAA regulations in force at the time of certification. Piper Aircraft does not recommend that these numbers be exceeded. It is also important to take into consideration that the aircraft must be kept within the CG envelope when loading in order to ensure safe operation of the aircraft.

Piper recommends that our aircraft be operated per the most current AFM/POH for the aircraft by serial number and model, remembering that it is the responsibility of the Pilot and aircraft Owner to ensure that the aircraft is loaded and operated properly.

Actually, there's still no mention of a "limit", a term that has a specific technical meaning in the context of aircraft regulation.

I'd simply go along with the email's second paragraph, which recommends compliance with the POH, which does not impose a per-seat limit (at least not for the Piper aircraft I've checked the POH for).

 

[Caramon13]

The BAS Harnesses I've put in are rated to 3000 lbs per harness. No way those things are going to break even at 6G. Yet another reason to put those in. I'm over 200 lbs.

 

[Jim_R]

Actually, there's still no mention of a "limit", a term that has a specific technical meaning in the context of aircraft regulation.

I'd simply go along with the email's second paragraph, which recommends compliance with the POH, which does not impose a per-seat limit (at least not for the Piper aircraft I've checked the POH for).

Gah!! Didn't realize I was chatting with a lawyer. I didn't use the word "limit" when summarizing the content of the letter the first time. ("...a query to the Piper home office elicited the reply that seats were certified to 170lbs, and Piper did not recommend that weight limit being exceeded.") I only used it this last time in a colloquial sense. I won't go back to edit it, but read it instead as "...references the 170# number" if that makes you feel better.

 

[Palmpilot]

Is this limit in the POH somewhere?

I was wondering the same thing. I've never seen a per-seat weight limit in Piper manuals, but I have to admit I wasn't specifically looking for it.

 

[Scott@KTYR]

I haven't seen 170 since 1974...

+1 ON THAT

 

[Jim_R]

Is this limit in the POH somewhere?

I was wondering the same thing. I've never seen a per-seat weight limit in Piper manuals, but I have to admit I wasn't specifically looking for it.

Yeah, part of the conversation involved how to interpret the wt/cg graph in the older AFMs, which show a line for pilot and passenger topping out at 420lbs. One of the questions in the discussion was whether that counted as a limitation or not. Eventually, that led to, "Let's ask Piper."

The only specific loading constraint in my AFM is that the baggage area is limited to 200lbs. Other than that, there's the wt/cg envelope. (Unless you want to argue that the wt/cg loading graph with lines for front occupants, rear pax, fuel, and baggage counts as a "constraint". I'm of the school of thought that that's simply an aid in calculating your wt/bal to ensure you're within the published envelope, which *is* a constraint.)

 

[flhrci]

I am thinking these weight limitations on seats will go up some day when these companies resize the "average" American or "average pilot" if there is such a thing. Hmmm, sensing a new poll coming....

David

 

[brcase]

If the aircraft is rated for 3.8 G positive and figure a factor of safety of at least 1.5 so now we're talking, what, 5.7 G positive so if you're 50% over that 170 pound limit you're giving up 0.5 G on breaking the airplane under severe conditions. Assuming the seat, or the fuselage beneath it, is even the weak link in the chain, which I doubt. I really don't think it makes that much difference.

Correction to bad math above, if you're 50% over the 170 then you're giving up your, supposed on my part, 50% factor of safety built into the aircraft, take it or leave it. Again, assuming the seat or the fuselage beneath is the weak link, which, again, I find a stretch.

The 1.5 Safety factor is often misunderstood. Airplanes are designed to two load limits. Limit Load and Ultimate Load.

To keep the math simple let use a plane with a 1000lb gross weight and a 3G Limit load.
So you can load up to 1000lbs and safetly repeatly pull 3G's without damaging the airplane, this is the Limit load, or 3000lbs of load

You could also safety load up to 500 lbs and pull 6G's, (maybe not practical or legal, but easy math) without damaging the airplane, still 3000lbs of load.

This airplane has a 1.5 safety factor or ultimate load of 4500lbs.

Now for the safety factor. For aluminum airplanes, generally aluminum will fail at 150% of it's yield strength. What this means is that if you repeatedly load 10% over, so 1100lbs at 3G= 3300lbs of the limit load, the structure of the airplane will not fail. However it may yield, ie damage the structure.

So contrary to popular belief most airplanes are not over designed. They are designed with a safety factor, but intruding on that safety factor only means the structure will not fail, not that the structure won't be damaged.

The example I once saw was a 182 that had a loss of control incident in IMC and over-stressed the wings. The wrinkles in the top skins of the wings obviously showed it had been over-stressed and the structure had been damaged, however the wings were still attached and the plane flew home but still needed the wings replaced afterwards, they exceed the limit load but not the ultimate load.
----
Another factor to consider in the above example, when calculating loads on the structure, the wings are not considered since they lift their own weight. This is why fuel is often carried in the wings because the fuel does not add to the non-lifting weight of the airplane and is not considered in the structural calculations for the fuselage. So while a pilot may think he is overloading plane by 10% the actual increase of load on the structure may be a 20% increase. Without know the design non-lifting weight of the airplane there is no way to know how much one might be overloading the structure.
Short answer is don't overload your airplane.
-----
Now composite airplanes are a different issue with their own set of design and manufacturing issues. Short version is that composites structures tend not to yield much and just fail. Plus the failure point is not as predictable as metal structures due to the manufacturing processes.
------
Back to the original post, Seat Design is a totally different science because now we are interested in crash worthiness and energy absorption which will usually withstand much higher limit and ultimate loads than the airplane will.
Brian
CFIIG/ASEL

 

[acrophile]

I didn't use the word "limit" when summarizing the content of the letter the first time. ("...a query to the Piper home office elicited the reply that seats were certified to 170lbs, and Piper did not recommend that weight limit being exceeded.").

Actually, you did use the word "limit" there.

 

[Jimmy cooper]

My cardio doctor, ( teaches at johns Hopkins) always pulls the tape measure out of his white coat and measures my waist. I'm 6 feet, weigh 185, used to weigh 195. He says anything over a 38 waist is trouble as it translates into too much fat. As for seat belts, if you don't have a good substantial shoulder harness to go with it your kidding yourself as your going to remake the panel in a most personal way should bad things happen, and probably die.

 

[JustinD]

Intresting topic! I wonder what the weight seat tested amount is for my 182!

I'm 5"7 and weigh 175Lbs dressed and ready to leave my place!

 

[N801BH]

My cardio doctor, ( teaches at johns Hopkins) always pulls the tape measure out of his white coat and measures my waist. I'm 6 feet, weigh 185, used to weigh 195. He says anything over a 38 waist is trouble as it translates into too much fat. As for seat belts, if you don't have a good substantial shoulder harness to go with it your kidding yourself as your going to remake the panel in a most personal way should bad things happen, and probably die.

Good news for me....

I have worn 34"/34" jeans since high school too...

 

[DavidWhite]

5'9 and somewhere between 145 and 165 depending on the time of year

 

[Jim_R]

Actually, you did use the word "limit" there.

<shoots self in head>

 

[denverpilot]

The BAS Harnesses I've put in are rated to 3000 lbs per harness. No way those things are going to break even at 6G. Yet another reason to put those in. I'm over 200 lbs.

At the attach points or just the belt?

 

[drotto]

I put no, but I am actually right on the line. I waver between 168 to about 172. On a really fat day I may get to 174.

 

[FLABrewer]

I put no as well but if it were 175 lbs. I would have answered differently.

 

[charheep]

With or without my wallet on me?