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80 lbs over gross TOW

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Old 07-27-2012, 02:41 PM
  #41  
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Never ask a question you don't know or won't like the answer to.

What if the guy would have told you he weighed 180 pounds? It would be legal but you know it wouldn't be true. Would you have gone?

This instance is black and white. The next time might be grey.

I've unfortunately flown a TP 1500 pounds over weight and out of CG. But hey, it was legal since I used the FAA approved weights.
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Old 07-27-2012, 06:01 PM
  #42  
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I havnt read what everyone else has said, but its always the pilot decision...no matter what anyone says, too ****ing bad for the owner... I'll cancel a flight if I get allergies...

Your the one responsible, not him. So when something bad happens in flight, your in deep **** when the investigators find out you were 80lbs overweight.

Ive seen inspectors hand out safety and negligence fines over thousands of dollars to students who would take a c172 to do one or 2 take off landings in the pattern with full fuel and no one on board with no w/b data given for that flight.

Remember risk management is apart of our business ( IMSAFE, PAVE ), you should be able to spit it out if someone asks you what they stand for and how it relates to you.
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Old 07-27-2012, 08:32 PM
  #43  
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Originally Posted by abelenky View Post
A former instructor and I recently had almost this same exact conversation, and here's how it came out.

First and foremost, as PIC, you absolutely can, should and MUST speak up if you aren't comfortable going. So I absolutely defend your choice in that regard.

However, here's what my former instructor and I went through when discussing it.

My C172 has a MTOW of 2400 lbs. That means it can climb, and do 3+ G turns at that weight, and do that with a safety factor of around 150%.
That means it could fly straight-n-level, un-accelerated flight at 2400lbs. x 3G = 7200lbs. and STILL have a safety factor of 150%.

WHOA: 7200lbs!

(granted, the plane won't take off at that weight. If it did, the climb performance will be non-existent, and its possible the landing gear may collapse on landing. But in the air, it would be theoretically fine)

As a result, I'd ask yourself: Are you planning on doing 3G turns? Are you taking off or landing at a short runway? Do you have obstacles at the end of the runway? Is it a hot day, or are there other factors affecting density altitude or airplane performance. Is the wind against you?

If the answer to ALL those questions works in your favor, you have to make a tough call. Flying illegal is illegal. If you got ramp-checked, or if there was an accident then it'd be your ass. But will the airplane perform at that weight? It seems likely it will.

The analogy of speeding 75 MPH in a 60MPH is pretty good. You might get a ticket, but the car won't fall apart around you.

The 3.8g testing requirement is not designed for people planning to go out and pull 3.8g's; this is the maximum that the faa feels is likely during a normal flight (such as, during turbulence). Very few people who take a 172 to the load limit had any plans to do that. And, by the way, at 3.8g's, you're 304 lbs overweight. So now, you hit some turbulence and you're temporarily 300 lbs over the design limit. By the way, that fudge factor (not 150% by the way) is designed to account for the fact that the testing was done on a brand new airplane, not one which has been flexing and slowly fatiguing for years.

Yes, the airplane would have flown, but you're a lot closer to your margins than this guy would have you think, especially if it's a bumpy day. There is a reason for a lot of the things the faa does, no matter how smart some pilots think they are.
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Old 07-27-2012, 09:38 PM
  #44  
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Originally Posted by abelenky View Post
That means it could fly straight-n-level, un-accelerated flight at 2400lbs. x 3G = 7200lbs. and STILL have a safety factor of 150%.

WHOA: 7200lbs!
Not really. You exceed that 3.8, and all bets are off. It may not have failed at that instance, but it could fail at any time thereafter. The 150% is a one-time thing, exceed that and it fails on the spot. You exceed 3.8 and you've likely damaged it. It's my understanding that 3.8 is the fatigue limit, where it can be cycled to with virtually no impact on the strength and structure (but in the real world this isn't really the case, as pointed out above). If you've gone past it, you've drastically changed the properties of the material and it's ability to stand up to tension or compression.

That conversation should never have gotten that far. Would you go 180mph on tires only rated for 160. It only seems like a little bit more, but can you fathom the effects of a blow-out at that speed? How many people really comprehend how the tire is constantly trying to tear itself apart at those speeds.
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Old 07-28-2012, 01:12 AM
  #45  
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Originally Posted by JamesNoBrakes View Post
That conversation should never have gotten that far. Would you go 180mph on tires only rated for 160. It only seems like a little bit more, but can you fathom the effects of a blow-out at that speed? How many people really comprehend how the tire is constantly trying to tear itself apart at those speeds.
That's a horrible example. If I have a slat/flap problem on my airplane, I'll exceed the rated speed of the tire.
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