Re: Is the 747-100 really "too" old ?

Date:         19 Feb 97 02:46:19 
From:         maclure@cvsrf1.arc.nasa.gov (MacLure)
Organization: NASA Ames Research Center
References:   1
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Jean-Francois Mezei <"[nospam]jfmezei"@videotron.ca> writes:

[SNIP]

>What exactly does this mean ?
>Are planes designed to "expire" after so many cycles ? What happens to
>maintenance schedules and certification process once a plane acheives
>its expected lifetime ?

Determination of the structural integrity of a design and of individual
aircraft of that design is a dynamic process involving detection and
testing. Aircraft are inspected at regular and mandated intervals.
Further, there is usually at least one manufacturer's test article that
stays well ahead of the fleet in terms of the hours "flown". When problems
are found they are the subject of engineering investigation and if possible,
repair efforts. Some airframes have estimated lives in the 100,000s of
hours range. IIRC, when the DC8 test article was shut down it had amassed
something like 250,000 equivalent hours. AT 12 hours per day usage thats
roughly 57 years of service.

>In the case of the 747-100, are we talking here about a plane that long
>ago passed its originally designed lifetime but was granted extentions
>because it was still in good shape ? Or was the plane truly past its
>lifetime with maintenance continuing and certification agencies not
>taking action (what action could be taken?) ???

No, what we are talking about here is a bunch of lawyers looking for
something to hang a lawsuit against someone with deep pockets on.

>What happens when a plane reaches its designed age ? Does this mean that
>the owner takes it apart, xrays the squeletton and rebuilds it with
>brand new parts, or does it just get a regular major check-up ?

If it can be repaired economically and lawfully it will be, otherwise
the plane is scrapped or sold.

IBM
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