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  • Flying on GE's Boeing 747 'Classic' flying testbed
    Posted by Guy Norris 11:15 AM on May 28, 2009

     I recently flew with General Electric’s flight test team based out of Victorville, Calif. Tests were focused on the GEnx-2B engine which will power the upcoming Boeing 747-8, first flight of which is currently expected in the late September-early October timeframe. (To hear more about the test program, we'll soon post a link to an interview with GE flight test director Al Krejmas.)

    The testbed is a first-generation 747-100 model, and the oldest version of the 747 still believed to be flying. The aircraft carries construction number 19651 and was the 25th 747 off the production line. It first flew on Mar 3, 1970 and was delivered to Pan Am as N744PA Clipper Star of the Union on Mar 21, 1970. According to Boeing’s customer numbering system, Pan Am was 21 so this specific variant of the -100 series is therefore a 747-121. It is also a well-cherished aircraft and kept in top condition, as can be seen by this view inside the GE flight test hangar prior to our mission (below).


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    After each flight, the aircraft is towed into the hangar and docked nose-in to the back wall where test crews and engineers can board directly from an elevated gantry mounted at main deck level. The approach to the main deck left hand door 1 provides a very unusual perspective on boarding, and gives the impression of entering a large ship rather than an aircraft.

     
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    Other than the limited instruments and controls dedicated to the test engine on the No.2 pylon, the flight deck retains the look and feel of the regular 747 ‘Classic’ cockpit.


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    Tom Drechsler, one of the GE engineering test pilots, indicates the crew escape hatch in the crown of the cockpit roof. Note the drop-down ladder in the small compartment behind his head. It certainly would require a dire emergency to use this exit which is 32 ft. above the ground when the gear is down!


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    Signs of Pan Am can still be traced everywhere from the airline’s blue paintwork on the spiral staircase to the upper deck, to the table top motifs in what was first class on the forward main deck. Before the end of its career with Pan Am it was renamed Clipper Ocean Spray. Pan Am retired it on Dec 4, 1991.

     
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    Here the crew throttles-up the GEnx-2B to test its relight capabilities after cold-soaking for several minutes high over the Sierra Nevada Mountains. Note the forward settings on the throttles controlling the three P&W JT9Ds.

     
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    A key test was the restart capability of the engine at low speed and relatively low altitudes. To keep the engine on its test condition at around 120 kts and 15,000 ft, we had to fly with a high nose-up attitude just above the stall. The extreme deck angle was interesting to experience back in the main cabin!


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    (Photo: Rick Kennedy)

    Here is a view of the captain’s P1 instrument panel later in the same test sequence. Note the pitch command bar on the flight director indicating 15 plus degrees of pitch, and the warning lights above.


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    From our test altitude at 15,000 ft. the adjacent peak of Mt Whitney – the highest summit in the contiguous United States – seemed ready to reach out and touch us – even though it was a couple of miles to our west and a scant 500 ft below.

     
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    The relative size of the GEnx-2B next to the JT9D (outboard) is seen in this view of the left wing as we head over the roof of the Sierras back to Victorville.


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    (All photos Guy Norris, except where indicated)

    Tags: tw99, General Electric, Boeing, 747, GEnx-2B

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