Re: Photo of Pan Am 747 W/5 engines

From:         Jim Manlove <>
Organization: The Boeing Company
Date:         28 Oct 96 03:06:34 
References:   1 2
Followups:    1
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  or MIME structure wrote:
> Spare engine carriage was developed due to the lack of 747 main deck
> freighters during the early days.  No narrow body freighter could
> accomodate a built-up big fan engine.  The combination of more
> wide body freighters and an increase in engine reliability has made
> spare engine carriage a rare event.

The 707 regularly carried a spare engine (turbojet much small than hi bypass)
on trans pacific routes.  The engines were much less reliable
and if an engine malfunctioned enroute to Tokyo they'd get there
on three, replaced the bad with the good, return with the bad
one for overhaul.  The original turbojets rarely went more than 100 hrs
without a malfunction.