On Apr 17, 5:53*am, tman inv@lid wrote:
I'm thinking through many of the factors, and it is only a "little" over
gross, only on the first hour or so of the trip. *What else should I be
aware of?

Many things. That's inherently the problem with operating outside the
certified limits. The certification limits provide you with certain
protections. By operating outside those limits, you give up some
protection. What do you give up? Well, that depends on what set the
limit.

Now there are two basic ways to approach this. First, you can
approach it the engineer way. That's how (modern) test pilots
approach this sort of problem. They operate outside the defined
limits all the time (it's in the job description) and most of them are
trained engineers anyway. They figure out what they are doing, what
they can expect out of the operation, decide whether the risk is
acceptable, plan for it, and fly the plan.

So how do you do this?

Start with the basics. What is the maximum available gross weight for
that make and model? Are there STC's that increase it? What sort of
gross weight limits are handed out on ferry permits?

Consider the effect on cg. The cg envelope generally narrows with
increasing weight.

Consider performance - what will climb be like? Cruise? How about go-
around with flaps? Perhaps you need to limit flaps on landing (in
case they don't retract)?

What about the g-loading? Normal category is 3.8, now you may have
less (or not - is that what limits gross weight on that plane?) - how
much turbulence can you expect?

Don't forget that for older planes, the W&B is mostly a work of
fiction anyway. The only real W&B is the kind you do with scales.
Most of them are done by subtracting the weight of equipment removed
(generally overestimated, because the cabling for avionics is mostly
left in) and adding weight installed (often underestimating because
fabbed cables and such are not included) and ignoring the
(significant) accumulation of dirt and grease.

Ultimately, what you are doing is substituting your judgment for
regulation. This has a lot in common with deciding that while the
speed limit is 55 here, in your judgment 60 is safe enough, even with
passengers in the car. If that's not something you would do, you
probably should not do this either.

Or there's another way. Hey, people do this all the time, seems to
work out OK, why not give it a shot? That's a lot how test pilots
used to operate way back when. A lot of them died that way, too.

*Am I dangerous?

Of course you're dangerous. You're considering transporting your
passengers by light airplane rather than a car. That's demonstrably
more dangerous. The question is whether the risk is reasonable for
you and them.

Now I happen to know (having faced almost this situation and done the
above analysis) that the margins are acceptable for me - and were
acceptable even when I had something like 100 hours. But who the hell
am I? Maybe I have graduate degrees in engineering, an ATP, and an
A&P - not to mention several kinds of CFI. Then again, maybe I'm just
a guy who plays flight sim a lot. Only the people who have met me and
flown with me know for sure.

If you're going to operate outside the rules, you really should know
what safety margins, if any, you are giving up - and that means doing
your own analysis.

Michael