Re: 747 forward cargo door

Date:         25 Nov 96 06:18:49 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>4) Did the HI incident result in any mods to the cargo door system?

My copy of the UA 811 accident report is dated April 16, 1990.  This
was before they recovered the cargo door from the ocean floor, and I
know a revised report was issued after that.  The report describes
three safety recommendations issued to the FAA on August 23, 1989.

The first was for an Airworthiness Directive (AD) requiring torque
limiting devices in the locking mechanism for the 747 cargo doors.
The FAA's analysis determined this to be unnecessary and upon
reconsideration, the NTSB agreed.

The other two recommendations were for an AD requiring positive
indication of latches and locks on all non-plug cargo doors, and a
certification requirement that designs of non-plug cargo doors take
into account possible human errors.  As of the report's date, the
FAA was still considering these recommendations.

>Is this completely crew dependent or are there specific security
>regs now in force that would force them to pull all the cargo for each
>passenger that leaves (which is what they were really saying)?

I've seen them delay a plane for nearly an hour when a passenger got
off at the last minute -- they pulled that passenger's bags, which
pretty much meant emptying the non-cargo portion of the belly.  I
believe this is now a requirement.

>Lastly, on the flight to SFO (another 747) the FA made quite a point of saying
>that this was one of several "odd" 747s that UA had purchased from Qantas and
>then went into detail where to find the handle to flush in the lav.  How many
>did UA get from Qantas?  Did Qantas have Rolls engines?

United acquired (most are leased, actually) seven ex-Qantas 747-238Bs
in early 1991, initially for the LHR routes purchased from Pan Am.
While Qantas has some 747-238Bs with Rolls-Royce RB.211-524D4 engines,
the ones United got were older ones equipped with Pratt and Whitney
JT9D engines.

>These sure sounded different on take off then the ones I'm used to

I've flown on these planes a number of times and never noticed any
different sound from United's other JT9D-equipped 747s.  They have
JT9D-7J engines, as opposed to the JT9D-7A engines on United's
747-100s, but the difference is relatively minor.  (Near the end of
their career with Qantas, they had JT9D-7FW engines.  I'm not sure
if UA or QF changed them.)

>Would UA have re-engined them if they were?

UA probably wouldn't have acquired them in the first place if they
had Rolls-Royce engines, but if they had, re-engining them would most
likely not be an option as you can't just unbolt an engine from one
manufacturer and bolt on one from a different manufacturer, even if
the basic aircraft was designed for either one.  Changes are needed
in everything from the cockpit instrumentation to fuel tanks -- the
747-400 has different fuel tanks depending on the engine chosen,
apparently due to differing locations of "hot spots" near the turbines
which require different "dry" areas in the wing above the pylons.

Aircraft can be re-engined -- the Seventy Series DC-8s, which are
Sixty Series aircraft with the original JT3D engines replaced with
new CFM56 engines, are one example.  However, this is an expensive
process, undertaken for many benefits beyond just fleet commonality.

(I have a vague recollection of several early MD-11s having engines
switched from GE to PW or the reverse after being manufactured.  Did
this actually happen, or is my memory playing tricks on me?)

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills