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

Date:         19 Feb 97 02:46:19 
From:         "Brian A. Reynolds" <bareynol@cca.rockwell.com>
Organization: Rockwell Avionics - Collins
References:   1
Next article
View raw article
  or MIME structure

Jean-Francois Mezei wrote:
>
> Recent news reports about TWA800 has shown one of the relatives speaking
> out on the 747-100 after a tour of the NTSB reconstruction site. He said
> that the plane was well past its planned lifetime and should have been
> retired years ago.
>
> 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 ?
>
> 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?) ???
>
> 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 ?

All aircraft are maintained on a schedule which takes into account
design limitations and expected lifetimes.  The initial planning for
long term aircraft maintenance occurs during the initial certification
process and involves the airlines and regulatory agencies.  The aircraft
airframe manufactures typically host these meetings and are invited to
participate as technical experts.  At one end is the A-checks which are
normal, routing maintenance normally perfomed during overnights.  At the
other end is the "Heavy D-check" during which it is not unusual to
totally rebuild an aircraft; at which time it is 'like new.'  All areas
subject to wear, fatigue, or corrosion are opened up and examined, then
rebuild to factory specifications if required.  Skins are removed to
gain access to all locations so nothing is left untouched.

Aircraft are typically removed from service when the economics of
rebuild plus the cost of continued operations with older (read less
efficient not less safe) exceed that of the projected benifit to be
gained.  (As is happening with older L-1011's for exampler where the
cost of operation is now significanly higher then newer aircraft making
the cost/benifit analyis come out in favor of newer and more economical
aircraft.)

A grieving relative of someone who died in an aircraft accident should
not be given any more weight then anyone else who is not aware of
policies, procedures, and requirements.  They are not technically
qualified to express a judgement; but they are entitled to their
opinion.  I would have to ask them however, how old their car is and
when was the last time that they checked for rusted through frame
members.

Brian