Re: B747 technical questions

Date:         27 Aug 97 03:57:52 
From:         stevec00@juno.com (Joel S Cole)
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>Lastly, in the book "727 Scrapbook" by Len Morgan, there is a chapter on
>a Braniff 727 where a dragging brake overheated a tire.  It exploded
>after retraction, and blew off the gear doors and a large hole in the
>top of the wing.  The aircraft made a safe landing.

  The most spectacular event I've seen(albeit on video tape) was the
Refused Takeoff Test of the USAF E-4 equipped with GE CF-6-50C engines.
  The RTO test was to certify the B747-200 at 800,000 lb TOGW for the
USAF.  The certified TOGW at that time was 178,000 lbs.  Boeing requested
to run the test at a heavier GW for Lufthansa. The USAF gave permission
for Boeing to fill the empty hull to 820,000 lb max TOGW.
   During the RTO test after max brakes were applied and before the a/c
slowly came to a halt, you could already see the wheel hubs glowing white
hot.  Even though the flames were invisible, you could tell there a fire
had started already.
   The test E-4 stopped and turned into the breeze and sat to wait out
the required time, unassisted by fire department.  Then thru the smoke
you could see puffs of smoke as the tires blew their fuse plugs.  Then
things really got popping.  Entire wheel & tires began to blow off the
axle.  One came off at enough speed to hit the bottom of the wing before
striking the far outboard engine(#1 or #4).  In all 5 wheels out of the
12 blew off the axles.  Test Engineers suspect that the brakes heat
output was so excessive that the entire wheel assembly was pushed off of
the axle.  The fire got out of hand and was put out, thus failing the RTO
test.
	One of the flight crew broke an arm during the evacuation(subject
of another thread).  The wing-to-body fiber glas fairing was damaged but
no metal was replaced- -primarily due to the fact that the aircraft had a
heavy coat of nuclear survivability paint covering it.
   This event is included on a Boeing Flight Test video, but the US Air
Force's camera had a better angle.

                                  STeve Cole~
                                  FedEx A/C Engineering
                        [ 2nd Lt on E-4 Program Office at the time]