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Date: Tue, 21 Jun 2005 19:25:21 -0400
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From: "Hamid A. Wasti" <hwasti@starband.net>
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Subject: Re: [LML] Re: Induction air filter
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Walter Atkinson wrote:

> There are two ways to accomplish that knowledge. Rigorous testing and 
> "let's see if this works." Both carry risks to the equipment. One 
> carries less risk to the flesh and blood. 

The problem with "Lets see if this works" approach is that you do not 
know how close you are to the edge and what little misstep (or maybe 
even an intentional one) is going to put you over the edge.  What is 
worse is the envelope creep.

The gross weight discussion from a few months ago is such an example. 
 One person decided to up the max gross on the Lancair IV by 100lbs and 
announced that they have been flying successfully for 500 hours (maybe 
only 5 of those hours being spent within 100lbs of the new gross 
weight).  The next person who learns that it has been tried and tested 
for 500 hours decides to up their weight by just another 100 lbs.  They 
report successful operations for 500 hours also (no landings, no rough 
air operations and only a few hours at the new high weight).  The cycle 
continues with each person building on the last person's "See I did it 
and I am still alive" experience till someone decides that based on 
existing published experience they can safely set their gross weight at 
5,000lbs.  Everything comes crashing down (quite literally) when that 
person falls out of the sky with three innocent passengers the first 
time they encounter moderate turbulence operating close to their gross 
weight and all the rest of us are left with the label of "those crazy 
people that think they are immune from the laws of physics"  

While not everyone can afford rigorous testing for everything they do, 
some educated analysis is mandatory.  "Lets see if this works" must be 
backed up with some sound engineering decisions -- assuming that someone 
else must have done the analysis otherwise they would not have done what 
they did is not part of sound decisionmaking.

Regards,

Hamid