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Subject: Re: [LML] Re: Necessity of A/C in IV-P?
From: Colyn Case <colyncase@earthlink.net>
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Ted,

Aside from the test pilot question, which I'm not qualified to address, =
I think we should be careful about drawing conclusions that a given =
modification is benign because it hasn't been implicated.   Most IVP's =
spend most of their time flying around at 1 to 1.5 G's and some don't go =
near Vne.    That represents almost no test coverage.    Most owners =
don't have the resources (e.g. multiple airplanes specially modified for =
egress, massive sensors, and test pilot time) to mount a serious test =
program.  That is why I would claim that engineering analysis is the =
cheapest option available.  =20

Colyn

On May 10, 2012, at 8:18 AM, Ted Noel wrote:

Hamid,

Your qualifications are well-established. but perhaps you are reading my =
comments to say something I'm not trying to say.

In any aircraft, there will be building variations. In production =
aircraft, the production test pilot serves to be certain that there are =
no deficiencies within the certified envelope. In our aircraft, there is =
no certified envelope. As a result, a good test pilot will attempt to =
establish a safe envelope. For example, the location of stall strips =
will be adjusted to tame the stall. With regard to the air conditioning =
holes, the obvious question is reduced structural integrity leading to =
reduced flutter margins. A good test pilot should be able to nibble at =
that edge of the envelope to identify a flight limitation (VNE).

We have a number of air conditioners flying, and I haven't heard of the =
holes being implicated in a structural failure. That doesn't mean that =
they won't be. But the fact that they are accumulating flight hours =
suggests that they may be safe.

If a structural analysis were to raise a big red flag, obviously that =
could not be readily ignored. But our continued flight testing suggests =
that that is unlikely.

Please note that I'm not declaring a settled question. Rather, I see a =
tendency in the data.

Ted Noel
N540TF

On 5/9/2012 1:38 PM, Hamid Wasti wrote:
> Ted Noel wrote:
>> 3. Flight testing with a competent test pilot.
>>=20
>> I think #3 is best since it deals with the variabilities of the =
installation and creates a hard VNE number.
> Does it? How much margin do you have? Testing is intended to validate =
engineering analysis, not to substitute it.
>=20
>> Also, there are a lot of A/C installations flying. This implies a =
degree of safety.
> Does it? How does your installation compare to the flying =
installations? How much safety margin do they have and how much will you =
have? How far have they pushed their airframe (intentionally and =
unintentionally) and how far will you push yours?
>=20
> All that the flying installations indicate is that no one has done =
anything in their aircraft that has led to the airframe failing due to =
the modifications. Maybe there is enough margin that it has not =
compromised safety at all. Maybe it has cut deeply into the safety =
margin and there have been a lot of very close calls that no one has =
known about.  Without a real engineering analysis taking the big picture =
in mind, no one really knows.
>=20
> Regards,
>=20
> Hamid
>=20
> --=20
> For archives and unsub =
http://mail.lancaironline.net:81/lists/lml/List.html
>=20
>=20
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>=20
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